The case for India switching from the oral to the inactivated polio vaccine Premium

No matter the polio status of a country and which vaccine is being used, as long as wild poliovirus is present and any country continues to use the oral polio vaccine (OPV), the risk of polio emergence, including in polio-free countries, is real in a globalised village especially when vaccine coverage is low.

This article is a response to ‘The case for the oral polio vaccine in the world’s quest for eradication’, July 21, 2023, by Vipin M. Vashishtha and Puneet Kumar.

In 2022, after more than a decade of remaining polio-free, the U.S., the U.K, Israel and Canada reported type 2 vaccine-derived poliovirus in environmental samples. The U.S. (Rockland County in New York) also reported one case of polio in a young adult caused by type 2 vaccine-derived poliovirus (VDPV) in July 2022.

What caused the type 2 VDPV case to emerge in the U.S.?

Vaccine coverage

Vaccine coverage with three routine doses of inactivated polio vaccine (IPV) in the U.S. was 92% in 2021. However, vaccine coverage in Rockland County in New York, where the young adult was infected by poliovirus and developed flaccid lower limb weakness, was very low —  60.3% in August 2022, and the zip code-specific coverage was as low as 37.3% — according to an August 2022 report in the Morbidity and Mortality Weekly Report (MMWR). Most importantly, the young adult who got polio was unvaccinated.

In March 2022, a three-year-old child in Jerusalem city, Israel developed polio due to type 3 VDPV. Like the young adult in New York, the child in Jerusalem city was not vaccinated. The type 3 VDPV virus was detected in six more children who were asymptomatic. “Of these seven children, one had incomplete polio immunisation while the other six were unvaccinated,” says a WHO report.

No matter the polio status of a country and which vaccine is being used, as long as wild poliovirus is present and any country continues to use the oral polio vaccine (OPV), the risk of polio emergence, including in polio-free countries, is real in a globalised village especially when vaccine coverage is low. While increasing vaccination coverage nationally and at a community level will help prevent children from getting polio disease, complete eradication from the world will become possible only when wild polioviruses are wiped out and the use of OPV is stopped.