Three hundred and fifty million doses of newly-developed polio vaccine nOPV2 have now been distributed across 18 high-risk countries, a feat the Global Polio Eradication Initiative (GPEI) says marks a “significant development for eradication efforts.”

The new oral polio vaccine was developed to better address the constant risk of type 2 circulating vaccine-derived poliovirus (cVDPV), a rare, mutated version of polio found in severely under-immunized communities low in adequate sanitation access.

While rare, with fewer than 1,000 cases recorded in the last decade, cVDPV has increased in recent years.

The new vaccine has become the first to be authorized under the World Health Organization'sEmergency Use Listing apparatus, which allows unlicensed vaccines to be accessed during public health emergencies, like polio outbreaks.

"Outbreaks of circulating vaccine-derived poliovirus continue to pose an equally menacing threat to countries,” the GPEI explained in a press release on May 25. “Through the rollout of a new vaccine to counter the most prevalent form of these outbreaks, cVDPV2, transmission has been stopped in the majority of countries that have deployed the tool.”

According to the GPEI, the vaccine has been “triple-locked using genetic engineering to prevent it from becoming harmful.” Benin, Congo, Liberia, Nigeria, and Sierra Leone are just some nations among the 18 high-risk countries that have received nOPV2 so far.

Earlier in May, at the 75th World Health Assembly in Geneva, the GPEI released its polio eradication strategy for the next four years. Despite a 47% decline in circulating vaccine-derived polio cases between 2020 and 2021, and just five cases of wild polio reported last year, the initiative says the world cannot become complacent.

Wild polio remains endemic in Afghanistan and Pakistan, and, in 2022, a case occurred in Malawi, the first since 1992.

On May 18, Mozambique similarly announced a wild polio case for the first time in three decades. 

The GPEI will hold a replenishment event this October in Germany in the hope of securing renewed financial support.

"A strong and fully funded polio program will benefit health systems around the world,” said Niels Annen, Germany’s Parliamentary State Secretary. “The polio pledging moment this October is a critical opportunity for donors and partners to reiterate their support for a polio-free world.”

The GPEI will be able to vaccinate 370 million children over the next five years if its strategy is fully funded.

Annen added: “We can only succeed if we make polio eradication our shared priority.”