Status: affected by circulating vaccine-derived poliovirus

A circulating vaccine-derived poliovirus type 2 (cVDPV2) outbreak in the Horn of Africa has been detected in Somali province, Ethiopia.  The virus was isolated from an acute flaccid paralysis (AFP) case with onset of paralysis on 20 May 2019, and a healthy community contact.

Genetic sequencing confirms that the isolated virus is linked to an ongoing cVDPV2 outbreak detected in the Horn of Africa in 2018, with cases reported in Somalia as well as from an environmental sample in Kenya.  Separately, Somalia is also affected by a circulating vaccine-derived poliovirus type 3 (cVDPV3) outbreak.

Since detection of the cVDPVs in the Horn of Africa in 2018, Ethiopia had declared this outbreak – together with the Ministries of Health of Kenya and Somalia – to be a regional public health emergency and has been participating in regional outbreak response.

Given cross-border population movements across the Horn of Africa and subnational immunity and surveillance gaps, Somali province is considered at high-risk of further transmission of this isolated cVDPV2.

The Ministry of Health and local health authorities are undertaking a detailed investigation and the partners of the Global Polio Eradication Initiative (GPEI) are providing support as required.  A full epidemiological and virological field investigation is ongoing; active surveillance is being strengthened; subnational population immunity levels are being analysed; and, outbreak response is being planned.

This event further underlines the risk of cVDPV2 across the Horn of Africa.

Polio this week in Horn of Africa

  • No case of circulating vaccine-derived poliovirus type 2 (cVDPV2) was reported this week. There are three cVDPV2 cases reported in 2019.
  • Somalia has reported a total of 15 cVDPV cases (eight type 2, six type 3 and one coinfection of both type 2 and type 3) since the beginning of the outbreaks.  The most recent cVDPV3 virus was from an AFP case from Runingod district, Middle Shabelle province with an onset date of paralysis on 7 September 2018.  Circulating VDPV2 has also been detected during 2018 in one environmental sample in Kenya collected on 21 March 2018.There are also two reported cases of cVDPV2 in Ethiopia, linked to Somalia in 2019.
  • Learn more about vaccine-derived polioviruses through this short animation or this ‘Coffee with Polio Experts’ video.

WHO risk assessment

WHO assesses the risk of international spread of cVDPV2 across the Horn of Africa to be high.

WHO advice

It is important that all countries, in particular those with frequent travel and contacts with polio-affected countries and areas, strengthen surveillance for AFP cases in order to rapidly detect any new virus importation and to facilitate a rapid response. Countries, territories and areas should also maintain uniformly high routine immunization coverage at the district level to minimize the consequences of any new virus introduction.

International Health Regulations

As per the advice of an Emergency Committee convened under the International Health Regulations (2005), efforts to limit the international spread of poliovirus remains a Public Health Emergency of International Concern (PHEIC).  Countries affected by poliovirus transmission is subject to Temporary Recommendations.  To comply with the Temporary Recommendations issued under the PHEIC, any country infected by poliovirus should declare the outbreak as a national public health emergency and consider vaccination of all international travellers.

Travel advice

WHO’s International Travel and Health recommends that all travellers to polio-affected areas be fully vaccinated against polio. Residents (and visitors for more than 4 weeks) from infected areas should receive an additional dose of OPV or inactivated polio vaccine (IPV) within 4 weeks to 12 months of travel.