Scientists at the UK’s Medicines and Healthcare products Regulatory Agency (MHRA) have helped deliver a major breakthrough in the global fight against polio, following the publication of a landmark international study in Nature Microbiology examining the performance of the novel oral polio vaccine type 2, known as nOPV2.
The research, jointly led by MHRA scientists and carried out with partners across Uganda, the United Kingdom, Israel, France, the Netherlands, the United States and the World Health Organization, provides strong evidence that the new vaccine is significantly more genetically stable than earlier oral polio vaccines. This stability is critical in preventing rare cases where weakened vaccine strains can mutate and circulate in under-immunised communities.
nOPV2 was designed in large part by scientists at the MHRA to address one of the biggest challenges in polio eradication: stopping outbreaks without unintentionally creating new ones. The findings now offer reassurance to health authorities, especially in Africa and other regions where polio remains a public health threat.
The study closely analysed 231 poliovirus type 2 samples collected from stool and sewage in Uganda between January 2022 and March 2023, following nationwide vaccination campaigns using nOPV2. Researchers found that the vaccine remained highly stable after administration, with key genetic modifications holding firm. These changes help prevent the virus from reverting to more dangerous forms, a known risk with older oral polio vaccines.
Importantly, the researchers identified only one rare recombinant strain that emerged after mixing genetically with other circulating enteroviruses. While laboratory testing showed this strain had increased neurovirulence, it did not spread widely in the population. Scientists believe this was due to strong vaccine coverage in the affected areas, reinforcing the importance of high immunisation rates.
Dr Javier Martin, Head of the Polio Laboratory at the MHRA and co-author of the study, said the results show the vaccine is doing exactly what it was designed to do. He noted that Uganda successfully halted circulating vaccine-derived poliovirus after two nationwide nOPV2 campaigns that reached around 20 million children, demonstrating the vaccine’s real-world impact.
MHRA’s contribution to the study was extensive. Its World Health Organization Global Specialised Polio Laboratory carried out advanced whole-genome sequencing using cutting-edge Illumina and Oxford Nanopore technologies. Scientists analysed virus samples collected on specialised FTA cards and conducted additional testing on sewage samples to confirm how the virus behaved in the community.
The work was supported by funding from the National Institute for Health Research, MHRA core funding, and the Bill and Melinda Gates Foundation, reflecting the scale of international cooperation required to push polio closer to eradication.
For diaspora communities, particularly those with strong ties to Africa, the findings are deeply significant. Polio has historically affected many low- and middle-income countries, and progress toward eradication directly impacts families with relatives back home. The study reinforces confidence in vaccination campaigns and highlights the role of UK-based science in protecting global health.
Researchers stress that while nOPV2 reduces the risk of dangerous genetic changes, ongoing surveillance remains essential. Monitoring sewage and clinical samples allows health authorities to detect rare mutations early and respond quickly. The study supports continued use of nOPV2 alongside the inactivated polio vaccine, backed by strong routine immunisation programmes.
The World Health Organization continues to classify polio as a Public Health Emergency of International Concern, and experts say the fight is not over. However, this research marks a crucial step forward, showing that science, global collaboration and sustained vaccination can bring the world closer to eliminating polio for good.
