WHO counts down Africa polio clock

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Africa could be declared free of endemic “wild” polio early next year if a strain last seen in Nigeria almost three years ago does not resurface, the World Health Organisation’s Africa head said, despite a new “vaccine-derived” outbreak.

A WHO report said two cases of the crippling disease were reported in Central African Republic, the 11th and 12th cases in Africa this year.

“There is a high risk of transmission of the virus as both cases were among internally displaced persons in an area with an estimated population of eight thousand,” the report said.

All recent African cases are “vaccine-derived” polio, which occurs in places with low vaccine coverage and poor sanitation as vaccinated people excrete the virus, putting unvaccinated people at risk.

The risk of vaccine-derived polio cases can be avoided by switching from live oral polio vaccines (OPV) – highly effective, cheap and easy to deliver but contain live virus – to “inactivated” vaccines (IPV), not effective for fighting the wild type but contain no live virus.

WHO Regional Director Matshidiso Moeti said vaccine-derived cases like those in Central African Republic were less alarming than the wild type virus still circulating in Pakistan and Afghanistan.

Africa’s last case of wild polio was recorded in Nigeria in 2016. Three years on the country can begin the months of paperwork needed before declaring the virus is no longer circulating, Moeti told Reuters.

“We are hopeful the way things are going, sometime early next year it might be possible,” Moeti said.

The use of OPV is being scaled down in a phased manner as countries eliminate circulating wild polio virus strains. If Africa is declared free of wild virus, health officials will switch to the inactive vaccine, removing the risk of more vaccine-derived cases.

“That’s the plan, that’s the hope,” Moeti said, adding she was cautiously optimistic.

There is no cure for polio, which attacks the nervous system and can cause irreversible paralysis within hours of infection. Children under five are most vulnerable.