Democratic Republic of the Congo

Nearly 1 billion people globally¹ are served by health care facilities that do not have regular or consistent power. Unreliable energy disrupts routine and emergency care—from running diagnostic tests to ensuring vaccines stay cold. As heatwaves, floods, and other extreme weather events become more common, energy disruptions are expected to increase due to events like power outages and heat stress on existing infrastructure. To address these challenges in the last mile of polio eradication and reduce its carbon footprint, the GPEI and partners have turned to solar power, a more affordable, reliable and climate-resilient energy source to power polio vaccination and surveillance activities.

Solar powered vaccine refrigerators

For decades,² refrigerators powered by fossil fuels like kerosene or petrol were essential to maintaining vaccines at just the right temperature. Yet, these refrigerators emitted greenhouse gases (GHGs), were relatively expensive to operate and were vulnerable to disruptions in the national energy supply. Now, the GPEI and its partners significantly rely on solar power, specifically, Solar Direct Drive (SDD) vaccine refrigerators.³ SDD refrigerators can run for days without power if needed, not only making them more dependable, but also extending the programme’s reach in some of the most difficult yet critical areas to end polio.

In the Democratic Republic of the Congo,⁴ a country the size of Western Europe with difficult terrain and longstanding security challenges, millions of children have missed out on polio and other life-saving vaccines in part because vaccines could not be kept cold on the trip to reach them. In 2016, just 16% of health centres in the country had a working refrigerator. Between 2018 and 2021, Gavi and its partners helped address this gap by delivering over 5,500 new solar-powered fridges across the country.

On the remote islands of Lake Chad,⁵ the introduction of solar powered refrigerators means that parents and health workers can simply go to the community center on the island, rather than travelling long distances by boat to receive or administer polio vaccines. Meanwhile, in Somalia, a country that experiences frequent interruptions in power supply, all vaccine refrigerators from the regional storage points down to the community-level administration are now powered by SDD refrigerators.

Solar powered surveillance

During surveillance, stool and environmental samples travel through the vaccine cold chain in reverse – from the field site or clinic to the regional and global laboratories for testing. In January 2021, an insurgency in Borno state, Nigeria, showed the world just how vital reliable, climate-resilient energy for surveillance is. The insurgency resulted in over ten months of power outages, including at the University of Maiduguri Teaching Hospital, which houses one of only two national polio laboratories in Nigeria. This meant that samples from the 10 most vulnerable states for polio transmission in northern Nigeria couldn’t be tested.

To help the lab get back on track as quickly as possible and prevent future power issues, the World Health Organization⁶ provided 48 solar panels. As a result, throughout most of 2021, more than 10,000 stool samples of children with acute flaccid paralysis (AFP) and more than 500 environmental samples were analyzed by the laboratory, an essential step to finding and stopping the virus.

In the face of the climate crisis and its many knock-on effects, including extreme weather events and even more persistent conflicts, health programmes like the GPEI must continue to integrate renewable energy at every turn. From refrigerators to powering entire laboratories, solar power technology has become a key energy source to help reduce the GPEI’s GHG emissions and ensure a polio-free future.

[1] Energizing health: accelerating electricity access in health-care facilities. Geneva: World Health Organization, the World Bank, Sustainable Energy for All and the International Renewable Energy Agency; 2023. Licence: CC BY-NC-SA 3.0 IGO
[2] https://www.unicef.org/innovation/stories/using-sun-keep-vaccines-cool
[3] https://apps.who.int/iris/bitstream/handle/10665/254715/WHO-IVB-17.01-eng.pdf;sequence=1
[4] https://www.gavi.org/vaccineswork/drcs-solar-revolution
[5] https://polioeradication.org/news-post/protecting-against-polio-in-lake-chad/
[6] https://www.afro.who.int/news/who-delivers-solar-panels-accredited-polio-laboratory-borno-state

Once children are vaccinated against polio, they are marked on their fingers to confirm their vaccination status. © WHO/AFRO

With 117 confirmed cases of circulating variant polioviruses and 107 detections in sampled wastewater so far in the African Region in 2023, the Africa Regional Certification Commission (ARCC) has urged countries and health partners to urgently address gaps in polio immunity to avert outbreaks.

The ARCC, which held it 31st meeting in the Democratic Republic of the Congo from 3 to 7 July, also called for an accelerate implementation of supplementary immunization activities, while considering challenges in accessibility to services including gender-related issues. The commission stressed the importance of gender equality in the polio fight, noting the crucial role women play in management, supervision, decision-making, message development and monitoring for polio control. The ARCC also urged countries to conduct robust preparations and ensure the vaccination campaigns are of the highest quality.

“The guidance will allow health authorities and partners to provide focused support to strengthen microplanning and social mobilization in areas with poor campaign performance, among other key areas of action“ said Professor Rose Leke, head of the Africa Regional Certification Commission.

The meeting gathered representatives of national and provincial health authorities from Chad, the Democratic Republic of the Congo, Ethiopia, Madagascar, Mali and Mozambique who committed to strengthen disease surveillance and consolidate the Expanded Programme on Immunization in hard-to-reach areas, with the support of the World Health Organization (WHO) and health partners.

Attendees took note of the increasing risk of poliovirus type 1 beyond Madagascar and the DRC, especially with the deterioration of routine immunization during the COVID-19 pandemic. Concerns were also raised regarding the persistently security-compromised areas, especially in Nigeria, that are impeding the elimination of circulating variant poliovirus type 2 (cVDPV2).

The commission, therefore, encouraged health authorities to also expand the use of Geospatial Information Systems to improve quality of surveillance and outbreak response.

“We are looking forward to implementing the additional ARCC recommendations to guide how we can deliver on the promise of polio-free Democratic Republic of the Congo and Africa,” said Dr Serge Emmanuel Holenn, Deputy Minister of Health of the Democratic Republic of the Congo, who applauded the commission, WHO and the Global Polio Eradication Initiative partners for the continued financial and technical support in the fight against polio in the country.

In addition to the DRC, Chad, Ethiopia, Madagascar, Mali and Mozambique also presented progress in polio control and lessons learned. Although certification of polio eradication occurs at the regional level, all countries with polio-free status are required to provide the certification commission with annual updates. These containment reports and outbreak preparedness plans allow for continuous monitoring.

The ARCC commended health authorities for their leadership in responding to ongoing polio outbreaks, as “this reflects the deep commitment and continued collective efforts by African countries and partner organizations to the fight against polio,” said Professor Leke.

The ARCC is an independent body established in 1998 to oversee the certification status of the African region as free from indigenous wild poliovirus. It continues to evaluate reliability of data in documentation submitted by National Certification Committees to ensure that countries are adhering to the criteria set for the global certification of wild polio virus. The ARCC meets twice a year to review progress made in the annual certification updates of selected countries on polio eradication activities of all the 47 member’s state of the WHO African region.

Originally published on the WHO AFRO website.

Through ongoing surveillance, the Global Polio Eradication Initiative (GPEI) has received notification of the detection of circulating vaccine-derived poliovirus type 2 (cVDPV2) in Burundi and the Democratic Republic of the Congo (DRC) linked with the novel oral polio vaccine type 2 (nOPV2). The viruses were isolated from the stool samples of seven children with acute flaccid paralysis (AFP) – six in DRC (eastern Tanganyika and South Kivu provinces), one in Burundi (Bujumbura Rural province) – and from five environmental samples collected in Burundi (Bujumbura Mairie province). All reported isolates stem from two separate and new emergences of cVDPV2 linked with nOPV2 that originated in Tanganyika and South Kivu provinces in DRC.

GPEI is supporting local authorities in both and neighbouring countries to conduct a thorough risk assessment and plan vaccination responses to reduce the risk of further transmission, as per outbreak response protocols. Burundi and DRC have scheduled initial vaccination campaigns to be conducted in April and based on the ongoing risk assessment, subsequent campaigns may be expanded to include areas in neighbouring countries.

Additionally, both AFP and environmental surveillance are being stepped up in the areas of detection, and the operationalization of further environmental surveillance sites is being evaluated. Samples from Burundi, DRC, and neighboring countries are also being prioritized for testing by the Global Polio Laboratory Network.

These are the first instances of cVDPV2 linked with nOPV2 since roll-out of the vaccine began in March 2021*. While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine. All available clinical and field evidence continues to demonstrate that nOPV2 is safe and effective and has a significantly lower risk of reverting to a form that cause paralysis in low immunity settings when compared to monovalent oral polio vaccine type 2 (mOPV2).

To date, close to 600 million doses of nOPV2 have been administered across 28 countries globally, and the majority of countries have seen no further transmission of cVDPV2 after two immunization rounds. Throughout the vaccine’s extensive field use, the strains in DRC and Burundi are the only two cVDPV2 emergences detected that have been linked with nOPV2. A preliminary assessment suggests an estimated 30-40 new cVDPV2 emergences, conditional on surveillance inputs, would have been detected by 1 March 2023 if mOPV2 was used instead of nOPV2 at the same scale.

Focused safety, effectiveness and genetic stability monitoring will continue for the duration of the vaccine’s use under WHO Emergency Use Listing (EUL) and work continues to advance towards nOPV2’s WHO prequalification, expected by the end of this year.

Importantly, eastern DRC is classified as one of GPEI’s seven most consequential geographies for poliovirus outbreak risk. Complex humanitarian challenges in the country, including insecurity, have created longstanding barriers to reaching every child with the polio vaccine. This has contributed to the continued spread of variant poliovirus within DRC and its exportation to nearby countries. GPEI continues to adapt its strategy and work with local authorities to protect all children from this devastating disease through targeted, flexible campaign efforts.

Ultimately, no vaccine sitting in a vial can protect a child. The success of nOPV2 and any polio vaccine depends on the ability to rapidly implement high-quality immunization campaigns to ensure that every child is vaccinated and poliovirus’ spread is stopped.

*cVDPV2 isolates collected in 2021 in Kebbi, Nigeria (from two cases and one contact), have since been confirmed to be linked to nOPV2. The Kebbi cases are therefore the first instances of cVDPV2 connected to nOPV2. No further circulation linked to the Kebbi isolates has been detected.

Vaccinators counting empty, open and broken vials under supervision in Bwamanda, Sud-Ubangi province. © WHO/DRC

‘Every single vaccine vial matters’ was the message ringing in participants’ ears following meetings between polio eradication counterparts across DR Congo, late last year. Led by the World Health Organization Africa Regional Office (WHO AFRO), health workers, epidemiologists, and experts in poliovirus containment, immunization and waste management came together to evaluate and get oriented on monovalent oral polio vaccine type 2 (mOPV2) safe usage and handling.

Participants examined how retrieval, packaging of empty, broken or partially used vaccine vials should be carried out following an immunization response to minimize risk of spillage and leakage, and learned about vaccine inactivation techniques.

“We’re dealing with a special kind of vaccine here – one that comes with significant containment implications,” said Dr Jacob Barnor, WHO AFRO Technical Officer for Poliovirus Containment. “The focus of these meetings was how we improve handling and accountability controls for mOPV2 – the only tool we have to effectively combat vaccine-derived poliovirus type 2 outbreaks ̶ so that we don’t see more of these outbreaks,” he added.

Orientation session on mOPV2 safe handling in Likasi, Haut Katanga province. © WHO/DRC

Since the declaration of eradication of type 2 wild poliovirus in 2015, to prevent the strain from resurging WHO has urged countries around the world to destroy or securely contain type 2 wild poliovirus materials. Strict measures for the containment of the weakened but live type 2 oral polio vaccine virus (OPV2) also exist and came into play after WHO ordered its removal from routine use in 2016.

The reason for its removal being that although effective in providing immunity against type 2 polio, in rare instances and given the right conditions, OPV2 can mutate into a form which can cause paralysis and death just like the wild virus. This reversion to virulence is known as type 2 vaccine-derived poliovirus (VDPV2).

The only oral polio vaccine now containing the OPV2 component is mOPV2, reserved for special use in responding to VDPV2 outbreaks.

“It’s a Catch-22. Circulation of VDPV2 can only be stopped by the live vaccine itself, contained in mOPV2,” said Dr Pascal Mkanda, WHO AFRO Polio Eradication Programme Coordinator. “The decision to use it, because of its implications, is not taken lightly. An advisory committee carefully weighs the risks and benefits of using mOPV2 and the vaccine is only released for use by the authority of WHO’s Director-General,” he added.

“We need to make sure that when mOPV2 is used in an immunization response, that it is used only when and where it is needed, and that every last vial is accounted for to prevent mismanagement. This requires a coordinated and careful approach across different partners and sectors. And this is what these meetings were all about: improving understanding of the various stakeholders to mitigate risks,” he said.

The evaluation and coordination meetings took place in Kinshasa, Gemena, Likasi and Goma, and involved more than 109 participants. Feedback has been positive with local health workers expressing appreciation for the guidance provided.

DRC is currently affected by an ongoing circulating vaccine-derived poliovirus type 2 outbreak. In 2018, 20 cases were reported. One case has been reported this year to date.

Related resources

The WHO AFRO Polio Team giving first-hand demonstration of ‘real-time’ surveillance system to delegates from KOICA. © WHO/AFRO — The WHO AFRO Polio Team giving first-hand demonstration of ‘real-time’ surveillance system to delegates from KOICA. ©WHO

During a visit to WHO’s Regional Office for Africa (AFRO) in Brazzaville by a delegation of officials from the Korea International Cooperation Agency (KOICA), delegates received a first-hand demonstration of the ‘real-time’ surveillance system for polio on the continent.

The WHO AFRO Polio Team giving first-hand demonstration of ‘real-time’ surveillance system to delegates from KOICA. © WHO

Dr Pascal Mkanda, head of AFRO’s polio eradication effort and his team demonstrated the newly-launched and real-time innovative mobile surveillance system, aimed at strengthening polio surveillance across the continent. Thousands of medical officers and health officers across the continent are dispatched to health clinics to actively search for cases of acute flaccid paralysis (i.e children with polio-like symptoms). Results of visits are communicated right back from the field level to the regional office in real time, via mobile phone technology.

This system is providing valuable and real-time evidence of poliovirus circulation, and helps drive strategic implementation. At the same time, the system is now being used to conduct active surveillance for other diseases, including cholera, NNT, measles, HIV and yellow fever, allowing for rapid response.

Developed in close coordination with the Bill & Melinda Gates Foundation, and are part of ongoing efforts to fill remaining subnational surveillance gaps, particularly in the lead-up to potential regional certification of wild poliovirus eradication (which could occur as early as late 2019/early 2020).

Africa’s polio eradication effort is generally supported by key private and public sector partners, including Rotary International. The Republic of Korea is a key partner in the effort, having contributed more than US$6 million to the effort, directly through KOICA. Support has been strategically allocated to supporting outbreak response and strengthening disease surveillance, and this visit builds further on Korea’s support to the global eradication effort. Strong disease surveillance is the underlying key strategic strategy, enabling rapid outbreak response as needed.

Related resources

In the Democratic Republic of the Congo, emergency response has been ongoing since 2017 to overcome outbreaks of circulating vaccine-derived poliovirus, caused by low rates of routine immunization. In the battle to close the outbreak, health workers, partners of the Global Polio Eradication Initiative, Governors of affected provinces, and the Ministry of Health are working together to vaccinate every child. In a context with weak health systems and other high-profile health and humanitarian emergencies, these united efforts are crucial to boost population health and keep all young children safe from paralysis.

A girl is vaccinated against polio in Manono, Tanganyika Province, during April activities in the Democratic Republic of the Congo. Credit: UNICEF / Serge WINGI

In the face of ongoing transmission of circulating vaccine-derived poliovirus (cVDPV) affecting the country, provincial governors from across the Democratic Republic of the Congo (DR Congo) convened an urgent emergency high-level meeting in Kinshasa last week, and signed the ‘Kinshasa Declaration for the Eradication of Poliomyelitis and the Promotion of Vaccination’. The high-level meeting was convened by HE the Minister of Health, as well as the WHO Director-General and the WHO Regional Director for Africa. Provincial governors committed to providing the necessary oversight, accountability and resources needed to urgently improve the quality of the outbreak response being implemented across the country.

Outbreak response since the cVDPV was first confirmed in 2017 has been marred by operational challenges, as too many children continue to remain un- or under-vaccinated. This new level of oversight can help ensure that operational deficits are rapidly identified and addressed. Partners of the Global Polio Eradication Initiative will continue to support authorities across the country, to ensure that this new level of commitment rapidly translates into operational improvements on the ground.

Kinshasa Declaration (in English)

Déclaration de Kinshasa (in French)

Children living in Raqqa, Syria, were immunized to rapidly raise population immunity, and stop the virus in its tracks. ©WHO Syria

The year’s end offers the chance to reflect on the polio programme’s milestones and challenges in 2017, and look ahead to what we can achieve in the coming year. 2017 saw the fewest wild polio cases in history — a total of 17 cases, or a 50% reduction from the year before—with these cases occurring in just two countries: Afghanistan and Pakistan. Yet the need to reach every last child is more important than ever, as demonstrated by surveillance gaps in Nigeria and outbreaks of vaccine-derived polio in Syria and the Democratic Republic of the Congo.

From programme strategies that helped protect progress and overcome obstacles, to commitments from donors and partners, 2017 demonstrated the resolve required to achieve a polio-free future. Accelerating progress in the new year and ending polio for good will require maintaining these political and financial commitments as well as building upon the programme’s efforts to find the virus wherever it exists.

Rooting out the virus

Throughout 2017, developments in disease surveillance – both in humans and in the environment – allowed the programme to better hone in on the virus and identify its remaining hiding places.

The drive to vaccinate every last child continued at the Afghanistan-Pakistan border. ©WHO / S.Ramo

For example, in Afghanistan, blood tests helped pinpoint which children have been reached and where gaps in immunity persist, allowing health workers to launch targeted vaccination responses. In Sudan, a pilot study used a new method of quality control to help ensure that stool samples arrive at the lab in the right condition for testing. And throughout the Eastern Mediterranean Region, environmental surveillance networks were expanded and strengthened.

These innovations are building robust, sensitive surveillance networks around the world that pick up every trace of the virus and enable the programme to develop targeted immunisation responses before polio has the chance to paralyse children.

Our surveillance teams worked to root out the virus in its remaining hiding places. ©GPEI

Overcoming challenges

The year also came with new challenges, including outbreaks of circulating vaccine-derived polio in Syria and the Democratic Republic of the Congo, where conflict has ravaged the health infrastructure. In these communities, and others where polio still exists, difficult terrain, conflict and highly mobile populations can all stand as hurdles to vaccinating children. Yet the polio programme continues to find new and effective ways of delivering vaccines.

Over 450,000 children were vaccinated against polio in Kabul, Afghanistan, in December 2017. ©WHO / Tuuli Hongisto

For example, in Afghanistan, a collaboration with a mobile circus is sharing important messages about polio vaccination with hard-to-reach populations, including those living in camps for internally displaced persons. In Pakistan, campaigns based at border crossings and train stations vaccinated children on the move who might otherwise have been missed by traditional methods. And in Syria, dedicated workers are delivering vaccines at transit points and registration centres for internally displaced persons. Thanks to these strategies, more than 255,000 children have been vaccinated in Deir Ez-Zor, 140,000 were reached in Raqqa and the programme continues to work to reach every child.

The mobile circus passed on vital health care and social messages, encouraging full immunization of every child. UNICEF Afghanistan / Ashley Graham

Renewed commitment to end the disease

Complementing these programmatic innovations were political and financial commitments that highlighted polio eradication as a priority for global health leaders. These included:

In May, the World Health Assembly reiterated the importance of eradicating polio and strategically transitioning the programme’s assets, and the G20 Health Ministers recognized the contribution of the polio infrastructure in helping countries face health emergencies during their first-ever meeting in Berlin.
At the Rotary International Convention in June, health leaders gathered and pledged US$1.2 billion to end polio. Just months later, the UK demonstrated its own longstanding commitment to eradication with a $130 million pledge.
At the G7 Health Ministers meeting in November, leaders once again affirmed their dedication to polio eradication as part of their broader commitment to strengthen health systems.

A child is vaccinated in Afghanistan during the September 2017 campaign. ©WHO / S.Ramo

Looking ahead to 2018

Next year, country programmes will need to continue working to ramp up surveillance, particularly in Nigeria, and reach children everywhere with vaccines. Cross-border coordination between Pakistan and Afghanistan, which has already had a huge impact in reducing cases, will continue to be critically important to stopping transmission.

At the same time, the global community is beginning to solidify plans for keeping the world polio-free once eradication is achieved. Countries are developing strategies for transitioning the infrastructure and tools that they currently use to fight polio. And the GPEI is working with global stakeholders and partners to develop the Polio Post-Certification Strategy, which will define the activities needed to keep polio from returning after the virus is eradicated.

If the remaining endemic countries continue to do all that they can to stop the virus, and if the global community continues to meet the level of political and financial commitment needed to make and keep children everywhere polio-free, 2018 will bring the world’s best opportunity yet to end the disease.

A child in west Africa receives polio vaccine. Photo: WHO.

More than 190 000 polio vaccinators in 13 countries across west and central Africa will immunize over 116 million children over the next week, to tackle the last remaining stronghold of polio on the continent.

The synchronized vaccination campaign, one of the largest of its kind ever implemented in Africa, is part of urgent measures to permanently stop polio on the continent. All children under five years of age in the 13 countries – Benin, Cameroon, Central African Republic, Chad, Côte d’Ivoire, Democratic Republic of Congo, Guinea, Liberia, Mali, Mauritania, Niger, Nigeria and Sierra Leone – will be simultaneously immunized in a coordinated effort to raise childhood immunity to polio across the continent. In August 2016, four children were paralysed by the disease in security-compromised areas in Borno state, north-eastern Nigeria, widely considered to be the only place on the continent where the virus maintains its grip.

“Twenty years ago, Nelson Mandela launched the pan-African ‘Kick Polio Out of Africa’ campaign,” said Dr Matshidiso Moeti, WHO Regional Director for Africa. “At that time, every single country on the continent was endemic to polio, and every year, more than 75 000 children were paralysed for life by this terrible disease. Thanks to the dedication of governments, communities, parents and health workers, this disease is now beaten back to this final reservoir.”

Dr Moeti cautioned, however, that progress was fragile, given the epidemic-prone nature of the virus. Although confined to a comparatively small region of the continent, experts warned that the virus could easily spread to under-protected areas of neighbouring countries. That is why regional public health ministers from five Lake Chad Basin countries – Cameroon, Central African Republic, Chad, Niger and Nigeria – declared the outbreak a regional public health emergency and have committed to multiple synchronized immunization campaigns.

UNICEF Regional Director for West and Central Africa, Ms Marie-Pierre Poirier, stated that with the strong commitment of Africa’s leaders, there was confidence that this last remaining polio reservoir could be wiped out, hereby protecting all future generations of African children from the crippling effects of this disease once and for all. “Polio eradication will be an unparalleled victory, which will not only save all future generations of children from the grip of a disease that is entirely preventable – but will show the world what Africa can do when it unites behind a common goal.”

To stop the potentially dangerous spread of the disease as soon as possible, volunteers will deliver bivalent oral polio vaccine (bOPV) to every house across all cities, towns and villages of the 13 countries. To succeed, this army of volunteers and health workers will work up to 12 hours per day, travelling on foot or bicycle, in often stifling humidity and temperatures in excess of 40°C. Each vaccination team will carry the vaccine in special carrier bags, filled with ice packs to ensure the vaccine remains below the required 8°C.

“This extraordinary coordinated response is precisely what is needed to stop this polio outbreak,” said Michael K McGovern, Chair of Rotary’s International PolioPlus Committee . “Every aspect of civil society in these African countries is coming together, every community, every parent and every community leader, to achieve one common goal: to protect their children from life-long paralysis caused by this deadly disease.”

The full engagement of political and community leaders at every level – right down to the district – is considered critical to the success of the campaign. It is only through the full participation of this leadership that all sectors of civil society are mobilized to ensure every child is reached.

More information

Children in Equatorial Guinea proudly show the dot of ink on their finger that demonstrates they have received a dose of oral polio vaccine. ©UNICEF/Equatorial Guinea

This week, 18 countries across western and central Africa have been holding synchronised polio immunization campaigns to reach nearly 94 million children with oral polio vaccine (OPV). This is a monumental coordination effort, incorporating strong governmental commitment, global support from international organisations such as the World Health Organization and UNICEF and the motivation of members of communities themselves to mobilize their friends and neighbours to ensure every child is protected.

National Immunization Days in Angola, Benin, Burkina Faso, Cameroon, Central African Republic, Chad, Cote d’Ivoire, the Democratic Republic of the Congo, Equatorial Guinea, Gabon, Gambia, Ghana, Guinea Bissau, Mauritania, Niger, Nigeria, the Republic of the Congo and Senegal are working to build immunity across western and central Africa. Each child needs at least 3 doses of OPV to build immunity and end the transmission of the virus, making it crucial that campaigns such as this reach every child.

Africa is closer than ever before to achieving eradication, with only 22 cases across the continent to date in 2014 compared to 232 by the same point in 2013. This decrease of over 90% in one year is due to increased commitment from the governments of the last remaining endemic country in Africa, Nigeria, and the sites of current outbreaks in Cameroon, Equatorial Guinea, Somalia and Ethiopia.

Nigeria saw only 6 cases in 2014 compared to 53 in 2013 by this date. This dramatic improvement can be attributed to measures put in place to avoid missing children from campaigns, and to a surge in staff to the country to support Emergency Operations Centres. The international spread of polio, affecting Cameroon, Equatorial Guinea, Somalia and Ethiopia as well as countries in the Middle East, lead to the declaration of polio as a Public Health Emergency of International Concern (PHEIC) in May 2014 by the Director General of the World Health Organization. With temporary recommendations to stop the international spread of polio, the PHEIC is another step towards ensuring a polio-free Africa.

Through these measures – improved surveillance, innovative community engagement strategies and a surge in staff to affected areas – the past year has seen gains in the eradication effort that must be protected. Synchronized campaigns such as this bring us ever closer to the important milestone of ending transmission in Africa.
These synchronised campaigns demonstrate the commitment of the governments of countries across central and western Africa to ending the transmission of polio once and for all, despite the increased focus on Ebola prevention and response in 2014. In some cases, polio resources are being utilized to strengthen the Ebola response, demonstrating the Global Polio Eradication Initiative’s commitment to securing the polio infrastructure for a polio-free world.

Polio vaccination in North Kivu at a camp for the internally displaced WHO/Eugène Kabambi

KINSHASA – More than a year after a child was last paralyzed by wild poliovirus in the country, the Democratic Republic of the Congo is preparing for a nation-wide polio immunization campaign on 11-13 July. Aiming to reach 16 million children under the age of five years, the campaign is essential to keep DRC polio-free. The campaign involves 19,000 social mobilizers to inform and involve communities, 90,000 vaccinators and more than 50,000 health workers giving de-worming tablets and Vitamin A supplements. For the first time in DRC, large-scale birth registration will be carried out, targeting 117 ‘zones de santé’ or health zones.

More [PDF] in French

Polio and Religion

PP2, Pastor of the Kitawala Filadelphie sect in the Democratic Republic of the Congo’s Katanga Province V.Petit / UNICEF DRC

This week, the Democratic Republic of the Congo confirmed that no children have been paralyzed by wild poliovirus in that country since December 2011. Persistent efforts by local health authorities have yielded this progress, but too many children still remain unvaccinated in the country, and success is by no means secure.

Some of these children went unvaccinated because of individuals like “PP2” – a charismatic pastor of the Kitawala Filadelphie Sect – who counseled his religious followers to refuse vaccination against polio. Now he has begun to change his approach; but the road to acceptance has been neither short nor easy. From hours spent passing a Swahili Bible back and forth in search of the final word on vaccinations; to a surprising decision to send young members of the sect away for medical training; to secret vaccinations in the dark of night – we trace, in this three-part series, the path of an unlikely alliance with a man who calls himself “The Elephant King.”

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Muhammad Ishaq, the first polio worker killed in Pakistan in 2012 – and tragically not the last WHO Pakistan/Edda Salvatori

“Are we seeing [polio’s] last stand?” asks the Independent Monitoring Board in their latest report. With the tremendous progress achieved in 2012, they certainly aren’t the only ones asking that question.
The year ended with the fewest children paralyzed by polio, in the fewest places, in history. Just over 200 cases have been reported so far for 2012 – a greater than 60% reduction from 2011. Over the year, through the tireless dedication of the on-the-ground heroes of polio eradication, more than 2 billion doses of vaccine were distributed to 429 million children around the world. And too many of these heroes gave their lives to reach some of the most vulnerable children in the world with vaccine.

India success sparks an emergency to finish the job

2012 was the year that India was removed from the list of polio-endemic countries. Angola and the Democratic Republic of the Congo both put a stop to re-established polio transmission.

The year began with a shake-up of the way the Global Polio Eradication Initiative (GPEI) was structured and does business. The partner organizations shifted into emergency mode from the get-go, looking to become faster, smarter and more innovative in getting the polio vaccine into the mouths of every last child. Accountability was a key focus across the board – from the heads of the spearheading partner organizations, down to the vaccinators in the field. And processes were put in place to ensure greater cooperation, not only between organizations, but between country-, regional- and head- offices.

This shift into emergency mode was formalised when the 194 Member States of the World Health Assembly, meeting in Geneva in May, declared the completion of polio eradication a “programmatic emergency for global public health”. This declaration announced that the global community was committed to ending this disease, and granted countries greater powers to prevent its spread.

Risk of international spread still real

Member States also called for the GPEI’s funding gap to be filled – something which has only just been achieved for 2012 with thanks to a number of traditional and new donors. Throughout the year, the increasing risk of a polio outbreak made many uneasy, as vaccination rounds were scaled back or cancelled as a result of this lack of funds, leaving more children needlessly vulnerable to polio in high-risk areas. The year closed with a new outbreak, in Niger – a reminder of the human cost of spreading poliovirus. If the funds can’t be raised to cover the costs of eradication and prevent further spread in 2013 and beyond, we run the risk of a polio resurgence. With so much progress made, there is all the more to lose.

Progress – and the path to success

A key factor in the progress in 2012 has been enhanced country ownership. All three remaining endemic countries – Nigeria, Pakistan and Afghanistan – implemented their own emergency action plans and introduced oversight mechanisms at the highest levels of government (such as the Presidential Task Force in Nigeria). The full force of administration was put into the effort – going beyond the health sector to a whole-of-society approach. This approach and intensity needs to be sustained to deliver ultimate success.

Strong commitment from the top levels of the Global Polio Eradication Initiative spearheading partners and unflinching support throughout the year from the UN Secretary-General, the UN Foundation and the Bill and Melinda Gates Foundation was critical to the progress seen in 2012.

In a historic display of solidarity at the UN General Assembly in September, leaders from around the world – including the heads of state from Afghanistan, Nigeria and Pakistan, donor government officials and new donors from the public and private sector – vowed to capitalize on progress achieved in 2012 and to step up the fight to eradicate polio. Days after, millions watched the web cast of a concert in New York’s Central Park to catalyze citizen action against polio.

Technical and programmatic innovation played a lead role in 2012, with GPS technology making a difference in ensuring that vaccination teams reach every child. The introduction of a direct disbursement mechanism in Pakistan ensured that health workers were paid directly and on time. Delegations from India to the remaining endemic countries helped transfer vital knowledge about micro-planning, accountability, strategies for special populations, and data collection.

All this paid off in more children being reached in the sanctuaries of the poliovirus. Nigeria was the only country which saw an increase in cases – and even there, more children were being reached with vaccine in the latter half of 2012 than in the first half.

Unacceptable loss

Tremendous sacrifices are being made to reach these children. Polio workers in Pakistan and Afghanistan lost their lives this year while working to protect children against polio. In Pakistan, a unacceptable and horrifying series of attacks on health workers brought the year to a tragic close. Their loss highlights the dedication and bravery of those who risk their lives so that the children in their community live their lives free of polio. Parts of all three endemic countries remain off-limits at the end of the year, but through the ongoing negotiations of partners we continue to reach more and more children, including around 30,000 children living in the Tirah Valley of Pakistan who were vaccinated in 2012 for the first time in three years.

Eradication – and endgame

So what’s next? The partnership is working on distilling the lessons learned from 25 years of polio eradication, including from India’s successful programme, into a plan to end polio and make sure it stays ended. Known as the “Polio Eradication and EndGame Strategic Plan 2013-18”, it sets out a blueprint for ceasing the transmission of both wild poliovirus and vaccine-derived poliovirus, providing support for strengthening routine immunization coverage in key target countries, provides for the safe containment of any poliovirus in laboratories and lays out a roadmap to ensure that the infrastructure put in place to fight this disease can be used to support other health interventions and services. In a historic decision, the Strategic Advisory Group of Experts on immunization called for a globally synchronized withdrawal of type 2-containing OPV – necessitating a switch from tOPV to bOPV in routine immunization programs.

Now that India has laid to rest the argument about whether polio eradication is technically feasible, and new emergency approaches are showing impact, this is the time for everyone to double our efforts, including the international development community. Everything is in place to secure a polio-free world, but without the funds to do so it won’t happen. On one side of the balance, a world free of polio where no child will ever know the pain of polio paralysis, and US$50 billion in economic benefits; on the other, resurgence of the disease resulting in 200,000 cases every year, within 10 years. All countries will benefit equally from global success. Ensuring that success is a global responsibility.

Examining one of the reasons children are missed during vaccination.

A woman from Katanga overtly refuses the polio vaccine as a result of herstrong religious beliefs and distrust in the vaccine due to previous forcedvaccinations in the region. UNICEF DRC/V. Petit

Deeply entrenched religious and traditional beliefs as well as a strong distrust of government health services undermine polio eradication efforts, particularly in Katanga

“We don’t trust the vaccine; we have faith in God who heals us. We trust in God,” says Maman Adèle in Katanga. A profound belief in divine intervention against polio, among many other religious and cultural beliefs, contributes to DR Congo’s high proportion of children who are unvaccinated due to parents’ refusal of the oral polio vaccine. Between 8-12% of children under-5 years old are left unvaccinated against the poliovirus after each of DR Congo’s polio vaccination campaigns, occurring almost monthly.

There could be many reasons for unimmunized children in DR Congo – vaccination teams may not have arrived at their designated households – either due to poor performance or logistical constraints; when teams do arrive, parents may refuse the vaccine; or they may inform front-line workers that children are not at home when they arrive. Among children that are missed each month, up to 40% are missed due to their parents’ refusal to accept the oral polio vaccine.

With 70 million people spanning a vast territory the size of Western Europe, a wide array of geographic, security and political challenges make DR Congo a particularly challenging context for polio eradication. A deeply entrenched social and cultural system that rejects ‘western medicine’ compounds the eradication effort in some of the highest risk areas.
To better understand the social norms underlying vaccine refusal, UNICEF has led a study to investigate the social reasons that explain why children continue to be missed during immunization campaigns.

Understanding refusals


Religious Leader Marco Kiabuta reaches to his followers to refuse vaccinations in the Mukwaka village, Katanga Province.

According to Independent Monitoring data, two main reasons contribute most to children not receiving OPV regularly in DR Congo- refusals and children’s absence. In the first quarter of 2012, approximately 46% of missed children were not vaccinated due to refusal, and 35% were due to child absence.

In some cases, reporting of child absence has been found to conceal vaccine avoidance behaviour, rooted in religious beliefs or distrust of government health services. In Kinshasa, parents who don’t want to give their children OPV are fairly outspoken in openly refusing it. But in other provinces, where children seem to be missed largely because they were absent at the time teams’ visited, and caregivers claim that they will accept vaccination during the next round, this willingness has been found to conceal a fear of reprisals from authorities for openly refusing OPV.

These findings and more have emerged from an October 2011 study led by a UNICEF-supported anthropologist, Veronique Goblet, and the Kinshasa School of Public Health.

While these beliefs also affect perceptions of routine vaccination in Katanga, where only 8% of children in this study were vaccinated, there was greater trust in routine services. Over a quarter of parents interviewed in Katanga said they have no issue with vaccinating their children at weigh-ins, where they can access other health services and where the decision to vaccinate is left solely to the child’s mother.

An OPV delivery strategy centred around health posts should be considered, in particular for Katanga, where reinforcing routine operations at key locations could also help reach children of migrant workers. These workers and their children sometimes travel over 100km to find work in farms, accounting for a large number of children missed at the household level.

Towards a polio-free DRC

For polio eradication to be successful in DR Congo, the programme must not only overcome logistical and operational challenges, but also understand the social reasons why children go unvaccinated. Religious and traditional beliefs, political distrust, rumours about OPV safety, and training of vaccinators on interpersonal skills are all key determinants of missed children in DR Congo. As is the case in other countries where religion and traditional beliefs drive refusals, UNICEF and its partners are engaging with religious leaders to initiate a dialogue that can bring a polio-free future to DR Congo’s children.

Read the full story.

Before dawn on the first day of the National Immunization Days in the Democratic Republic of the Congo, Vaccinator Antoine Ngusu Hely is fully awake despite the early hour.

Vaccinator Antoine Ngusu Hely vaccinates an adult woman in Kaemie, DRC. Photo: UNICEF/Bibimbu

At the health center of Kitutu, a storage site in the health zone of Nyemba in Kalemie, he tells us: “Yesterday evening I programmed the alarm on my phone for 4 AM to make sure that I will be on time at the storage site to gather all my vaccination equipment.

He maintains his dynamic throughout the day. In the evening he has a big smile and expresses his satisfaction. “I didn’t meet any family that refused the vaccination.”

His fellow vaccinator Kabazo Ildefonso, in the health area of Kalemie’s University knows that vaccination affects not only children but also adults. Shortly before leaving his house at 6 AM this morning, he had instructed his wife to get their child immunized but also herself.

Ildefonso’s first stop is at the health center Kituku, which also the space to store vaccines and vaccinator equipment. “I didn’t want to start my vaccination journey without ensuring that the amount of vaccine is sufficient, that the expiry date of vaccines is good”, as he explains.

When we meet him again at the end of the day Ildefonso has a big smile on his face “I am quite satisfied with the work of this first campaign day.” And indeed, besides reaching dozens of families in his area of intervention the young man also had to vaccinate staff from international organizations (WFP, UNICEF), NGOs and students of the University of Kalemie. He hopes to reach at least a similar number the following day.

In the Kinshasa area, the vaccination days were launched by a musical group made up of polio survivors.

child is one too many, reads this poster at an anti-polio concert. Photo: WHO/E. Kabambi Kabangu

African Vaccination Week in DRC (en français)

Religious leaders’ support critical to help increase community vaccination acceptance and coverage in the country

A girl receiving oral polio vaccine. WHO/C. Lamoureux

Ahead of the next National Immunization Days (NIDs) on 20 October, religious leaders from across the Democratic Republic of the Congo (DR Congo) have come together to pledge their support for polio eradication.

At a meeting on 8 October 2011 in the country’s capital, Kinshasa, Dr Victor Makwenge Kaput, Minister of Public Health, convened the heads of the major religious affiliations to solicit their – and by extension their constituents’ – support for polio eradication. “The persistence of polio in three areas of our countries is linked to a high number of people who refuse vaccination and therefore the risk increases of increased circulation of this outbreak in our country,” he said. “The role of religious institutions is critical to help overcome any community resistance. It is the leaders of these institutions who are trusted and respected by communities across the country.”

The Minister expressed optimism that with the support of the religious leaders’ engagement, who are viewed by their constituents as a trusted source of information, community resistance can be overcome and more children will as a result be vaccinated and protected from poliovirus.

Religious leaders across the countries will now actively engage their communities in the polio eradication effort, and underscore the risk polio and non-vaccination poses to children everywhere.

Independent Monitoring Board report

The Democratic Republic of the Congo, May 2011: A child's finger is marked with indelible ink after being vaccinated against polio. Christine Lamoureux/WHO — The Democratic Republic of the Congo, May 2011: A child’s finger is marked with indelible ink after being vaccinated against polio.
Christine Lamoureux/WHO

The report of the 30 June-1 July meeting of the Independent Monitoring Board (IMB) affirms that polio eradication can be achieved in the near-term, but that ‘this will not happen if things continue as they are.’

In particular, the IMB expresses concern at the situations in DR Congo, Chad and Angola, and the continuing increase in cases in Pakistan.

The IMB underscores ‘7 important positive signs’ which – if achieved by end 2011 – would affirm that the programme is back on track to interrupt all polio transmission by end-2012:

1. no recurrence of cases in India by end-2011;
2. interruption of transmission in Kano and the surrounding north-west areas of Nigeria by end-2011;
3. interruption of type 3 poliovirus globally by end-2011;
4. a major expansion in capacity and expertise in Chad and DR Congo, with independent monitoring, surveillance data and case numbers clearly reflecting the impact of this expansion by end-October 2011;
5. a clear decline in the number of cases in Pakistan in the second half of 2011, compared to the equivalent
period in 2010, with particular evidence that the National Emergency Action Plan is working in Sindh province;
6. no more ‘surprises’ with re-emergence of the disease in polio-free countries; and,
7. a decline in field reports suggesting poor or variable quality of vaccination campaigns and surveillance, and/or
inadequate local leadership.

The IMB also expresses serious concern at the ongoing global funding gap, calling it ‘deadly serious’, and highlighting that – although the GPEI has long standing support from a core group of partners – it is neither right nor sustainable that the burden of financing should rest disproportionately on a narrow funding base. The Board concludes that there are a number of richer countries that have called for polio eradication, but have barely supported it financially.

The GPEI welcomes the findings and recommendations of the IMB. The heads of the spearheading partner agencies – the World Health Organization (WHO), Rotary International, the US Centers for Disease Control and Prevention (CDC) and UNICEF – and the Bill & Melinda Gates Foundation, will over the coming weeks discuss the report and its implications, and commit to specific actions to further support countries’ eradication efforts.

The IMB was established in 2010 at the request of the Executive Board of WHO and the World Health Assembly, to monitor progress against the milestones of the GPEI Strategic Plan 2010-2012.

Independent Monitoring Board

Everyone in the capital city is vaccinated in response to a large polio outbreak in the Democratic Republic of the Congo. This year, 10 of the 26 cases of wild polio virus in the country have been registered in Kinshasa.

By Cornelia Walther

Kinshasa, March 2011: While waiting until the National Football Team is ready to get vaccinated against polio, a security officer takes his chance UNICEF/C. Walther — Kinshasa, March 2011: While waiting until the National Football Team is ready to get vaccinated against polio, a security officer takes his chance
UNICEF/C. Walther

KINSHASA, Democratic Republic of the Congo – The national football team was vaccinated against polio last week as part of a five-day vaccination drive to help stop polio in Kinshasa. The campaign, organized by the government with the support of polio eradication partners, aimed to reach more than eight million people.

This year, 10 of the 26 cases of wild polio virus in the country have been registered in the capital (as of 29 March). The disease usually affects mostly children, but the latest outbreak of polio in DR Congo – which began last year – is also now increasingly found in adults, among whom it takes its most severe form.

As part of the campaign, the entire national football team was vaccinated by a mobile vaccination team in Kinshasa’s stadium. A total of more than 5,000 mobile vaccination teams visited schools, markets, health centres, offices and homes.

UNICEF National Ambassador and captain of the DR Congo’s football team, Tresor Lualua, supported the campaign. “Children are our future,” he said. “That’s why it would be inexcusable to not ensure that they are in good health.”

Despite logistical challenges, the campaign was a success. So much so that by the last day, showing the ink-stained small finger of your left hand – which signified you’d been vaccinated – became a form of greeting.

“Whenever we asked someone on the street if he or she was vaccinated, they showed us their marked finger,” said the chief doctor of the Kinshasa Health Zone, Barumbu Gentil Mulumba. “It’s like a secret code.” More

February 2011: In late 2010, a deadly polio outbreak struck the Republic of the Congo. It is the deadliest reminder in recent memory that unless eradicated, polio will spread internationally, with tragic human consequences. Mass immunizations are taking place to stop the outbreak.

See the photo essay

Increased risk of international spread

Angola and the Democratic Republic of Congo (DR Congo) are experiencing outbreaks of wild poliovirus type 1 (WPV1).

In Angola, the outbreak which began in April 2007, has this year spread to re-infect previously polio-free areas in Angola (the provinces of Bie, Bengo, Huambo, Lunda Norte, Lunda Sul and Uige), as well as to neighbouring DR Congo, re-infecting Kasai Occidental province which borders Angola. This outbreak is classified as ‘re-established’ transmission, as it has persisted for a period greater than 12 months.

In DR Congo, in addition to newly-imported virus from Angola this year, a case detected in Katanga province with onset of paralysis on 20 June 2010, in the east of the country, has been genetically-linked to virus previously imported from Angola, last detected in eastern DR Congo in 2008. In 2009, a case was detected in Burundi, which was linked to the same transmission chain. DR Congo was previously regarded by the Advisory Committee on Poliomyelitis Eradication (ACPE) has having ‘suspected’ re-established transmission, and this suspicion is now confirmed.

Given the recent progress achieved in Nigeria (99% reduction in cases this year compared to the same period in 2009), west Africa (no cases since 1 May 2010) and the Horn of Africa (no cases in more than 12 months), central Africa is now considered to be the greatest risk to Africa’s polio eradication efforts. Angola’s outbreak is currently the only geographically expanding outbreak in Africa. This situation increases the risk to achieving the next global milestone of the new Global Polio Eradication Initiative (GPEI) Strategic Plan 2010-2012, the cessation of all re-established WPV transmission by end-2010.

There is currently a high risk of international spread of WPV from Angola and DR Congo, given the limited impact to date of control measures and the historical cross-border spread from both countries. In 2010, outbreak response in both countries has been inadequate to stop transmission of the imported viruses. Independent monitoring of supplementary immunization activities (SIAs) indicate as many as 25% of children are regularly missed during SIAs in key areas of Angola (including Luanda, Lunda Norte and Lunda Sul). In DR Congo, no response activities have been conducted in the east of the country since November 2009. The outbreaks require urgent action to reach a higher proportion of children with oral polio vaccine (OPV) across Angola and DR Congo and improve surveillance across Angola and DR Congo. Due to sub-national surveillance gaps, further undetected circulation of WPV1 cannot be ruled out. Given the increasingly widespread transmission of WPV1 in Angola and documented spread to DR Congo, the World Health Organization (WHO) considers the risk of further international spread as high. Given persistent undetected transmission of WPV1 in eastern DR Congo, and historical evidence of international spread, WHO considers the risk of further international spread as high.

Urgent improvements are needed during SIAs and to fill sub-national surveillance gaps for acute flaccid paralysis (AFP), through strengthened engagement and ownership by provincial- and district-level political and administrative leadership. In Angola, National Immunization Days (NIDs) are planned for September, and additional responses are being discussed. In DR Congo, SIAs are being carried out in response to the new importations, and an urgent SIA and surveillance strengthening plan is being developed in response to the detection of the new case in the east of the country which confirmed persistent undetected transmission in that area.

It is important that countries across central Africa and the Horn of Africa strengthen AFP surveillance, in order to rapidly detect any poliovirus importations and facilitate a rapid response. Countries should also strengthen population immunity levels to minimise the consequences of any virus introduction. As per recommendations outlined in WHO’s International travel and health, travelers to and from Angola and DR Congo should be fully protected by vaccination.

A persistent outbreak of polio in Angola is geographically expanding in 2010

National Immunization Day in Angola Hans Everts/WHO

A persistent outbreak of polio in Angola is geographically expanding in 2010, with cases detected since February in previously polio-free provinces of Angola (Bie, Bengo, Huambo, Lunda Norte and Lunda Sul), and one genetically-related case in the Democratic Republic of the Congo (in Kasai Occidentale province, which borders Angola) on 25 May. Angola could become the greatest risk to polio eradication in Africa, given the significant progress being achieved in Nigeria and other parts of west and central Africa.

The epicentre of the outbreak is the capital Luanda. The country has had a persistent outbreak of poliovirus type 1 (WPV1) since 2007, where 8 cases were reported that year, and 29 cases each in 2008 and 2009.

Given the persistent and widespread transmission of wild poliovirus, ongoing sub-national surveillance gaps and recent further spread of WPV1 internationally, WHO considers as high the risk of further international spread into neighbouring countries. As per recommendations outlined in WHO’s International Travel and Health recommendations, travellers to and from Angola should be fully protected by vaccination.

Angolan Minister of Health Dr José Vieira Dias Van-Dúnem re-affirmed Angola’s strong commitment to stop polio transmission by end-2010. In 2010, Angola has conducted a sub-national supplementary immunization round using monovalent OPV type 1 (mOPV1) targeting high risk provinces from 7-9 May, a national immunization round from 11-13 June using a combination of trivalent OPV (tOPV) and mOPV1, and mop-up immunization campaigns with mOPV1 in response to WPV1 cases (on 23-25 April in Bie, and on 4-6 June and 18-20 June in Lunda Norte and Lunda Sul). Further national immunization rounds are planned for early August and September. The Democratic Republic of the Congo conducted mop-ups on 4 June and 18 June with mOPV1, and further outbreak response is currently being planned.

In 2009 and 2010, immunization coverage has been sub-optimal, with as much as 25% of children regularly missed during supplementary immunization activities (SIAs) Urgent action is needed to ensure that all children in Angola are reached with oral poliovirus vaccine during the SIAs taking place in August and September, through strengthened engagement and ownership of SIA operations by provincial- and district-level political and administrative leadership.

It is important that countries across central Africa, in particular those bordering Angola, strengthen disease surveillance for AFP, in order to rapidly detect any poliovirus importations and facilitate a rapid response. Countries should also continue to boost routine immunization coverage against polio to minimize the consequences of any introduction.