GENEVA — More than 33 million children in several southern African countries have been vaccinated against polio as part of ongoing efforts to eradicate the infectious paralytic disease that has been largely contained in most of the world, the World Health Organization (WHO) announced Friday.

About 80 million drops of the inoculation have been given orally to children across Malawi, Mozambique, Zambia, Tanzania, and Zimbabwe since the launch of an emergency response in March 2022, the UN health agency said in a statement.

Africa was certified as free of indigenous wild poliovirus in 2020. But Malawi detected wild polio in a young child in its capital, Lilongwe, in February 2020, and the virus spread to neighboring Mozambique, which recorded the last of eight confirmed cases in August 2022.

The WHO said the recent polio strain originated from Pakistan, which along with neighbor Afghanistan are the only two countries where the virus remains entrenched.

Vaccinations will continue in southern Africa “so that every child receives the protection they need,’” said WHO Africa director Dr. Matshidiso Moeti.

At least five vaccination rounds are planned for this year, following 19 that took place last year, she said, adding the region has “made huge efforts’” to strengthen polio detection and control the spread of the virus.

Concerted emergency response launched following the outbreak in 2022 has helped increase protection among children through vaccines in Malawi, Mozambique, Zambia, Tanzania and Zimbabwe.

The countries have also ramped up disease surveillance and community mobilization to help find cases and halt the virus.

“Southern Africa countries have made huge efforts to bolster polio detection, curb the spread of the virus and ensure that children live without the risk of infection and lifelong paralysis,’” said Moeti. “We continue to support the polio control efforts across the region so that every child receives the protection they need.’”

More than 10 new environmental surveillance sites have been set up over the past year in the affected countries with support from WHO. The fully operational sites are playing a critical role in the efforts to detect silent circulating poliovirus in wastewater.

“Response teams have worked intensely in the fight against polio not only in Malawi but in the rest of the neighboring countries in a coordinated manner. We will not rest until we reach and vaccinate every child to stop polio transmission,’” said Dr. Emeka Agbo, acting country coordinator for the Global Polio Eradication Initiative in Malawi.

Reaching all households where eligible children live is critical to protect them against the risk of paralysis. The national health authorities, with support from the Global Polio Eradication Initiative, efforts are ongoing to map cross-border communities, migratory routes, border crossings and transit routes.

“Community health workers have been pivotal in the vaccination campaigns and will continue going door-to-door, bringing polio vaccines to children who might otherwise be missed,’” said Dr. Jamal Ahmed, WHO polio eradication program manager.

Polio is highly infectious and affects unimmunized or under-immunized children. In Malawi and Mozambique, it has paralyzed children younger than 15 years.

There is no cure for polio, and it can only be prevented by immunization. Children across the world remain at risk of wild polio type 1 as long as the virus is not eradicated in the last remaining areas in which it is still circulating.

On Jan. 25, 023, the WHO Emergency Committee under the International Health Regulations concluded that the risk of international spread of poliovirus remains a public health emergency of international concern. — Agencies