Polio eradication is in its final stages. Two wild-type poliovirus serotypes have been eradicated, and the third hangs on in Afghanistan and Pakistan, but it is hoped transmission will be halted by next year.

Mass oral poliovirus vaccine (OPV) campaigns have been central to the Global Polio Eradication Initiative (GPEI) strategy, but must eventually cease because OPV can rarely evolve to regain neurovirulence and trasmissibility. Poliomyelitis outbreaks caused by vaccine-derived polioviruses (VDPV) have been reported in 25 countries since 2000. The GPEI strategic plan for 2013-18 envisages globally synchronised OPV withdrawal, which began with serotype 2 in April 2016.

The MRC Centre for Outbreak Analysis' Vaccine Epidemiology Research Group (VERG) led by Nick Grassly is a WHO collaborating institute on polio data analysis and modelling, and contributes to the GPEI strategy. In 2015-16 a focus has been illustrating the trade-offs between minimising the risk of seeding new VDPVs with trivalent OPV campaigns and ensuring population immunity against each serotype. The GPEI has since adopted a risk-based strategy that targets specific countries with multiple campaigns, and routine OPV-use boosted with the inactivated polio vaccine. The VERg works with WHO, Bill and Melinda Gates Foundation, Center for Diease Control and other GPEI partners to: optimise surveillance data usage, develop and apply methods estimating the sensitivity of environmental sample sites, quantify transmission from poliovirus genetic sequence data, and use algorithms to detect outbreak signatures before laboratory tests are complete. The responsive nature of the group to the GPEI's needs is facilitated by working groups and task team memberships.

Academic staff