Oral polio vaccines: evolving tools for eradication and beyond

Oral polio vaccines (OPVs) have been at the heart of global efforts to eradicate polio. Their ability to induce strong intestinal immunity and interrupt person-to-person transmission has made them an essential tool in reducing wild poliovirus cases by more than 99% since 1988.

As the programme moves closer to eradication, OPV use continues to evolve to address both remaining wild poliovirus transmission and outbreaks of circulating variant polioviruses (cVDPVs).

From trivalent to targeted OPV use

Over time, OPV formulations have been adapted to respond to the changing epidemiology of poliovirus. Following the global withdrawal of type 2-containing OPV in 2016, bivalent OPV (bOPV), targeting types 1 and 3, became the primary vaccine used in endemic and high-risk settings.

As the world approaches interruption of wild poliovirus transmission, future vaccine use will continue to be guided by epidemiological need and global policy recommendations.

For more information on the planned cessation of OPV use and the long-term strategy for sustaining a polio-free world, please refer to the Sustaining a Polio-Free World:  a strategy for long-term success.

Novel OPVs: reducing outbreak risk

A major recent innovation has been the development of novel oral polio vaccines (nOPVs), designed to be more genetically stable and less likely to revert to forms that can cause outbreaks.

• nOPV2 is now in use for cVDPV2 outbreak response and has been prequalified by WHO with two manufacturers, supporting global supply and rapid deployment.
• Clinical development is ongoing for nOPV1 and nOPV3, as well as for trivalent novel OPV (tnOPV) candidates, which aim to provide protection while maintaining improved genetic stability.

These next-generation vaccines are an important step in improving the safety and effectiveness of outbreak response as the programme approaches eradication.

Looking ahead

As the world moves toward a polio-free future, vaccine strategies will continue to adapt.

In the near term, OPVs remain essential to interrupt transmission. In the longer term, once eradication is achieved, OPV use will be phased out globally, with inactivated and non-replicating polio vaccines playing a central role in maintaining population immunity.

Ongoing research and innovation are critical to ensuring that the world not only achieves eradication, but sustains it.