WHO counts down Africa polio clock despite new outbreak
By Tom Miles
GENEVA, May 28 (Reuters) - 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 Organization's Africa head said on Tuesday, despite a new "vaccine-derived" outbreak.
A WHO report earlier on Tuesday said two cases of the crippling disease had been reported in Central African Republic, only 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 have been "vaccine-derived" polio, which occurs in places with low vaccine coverage and poor sanitation as vaccinated people excrete the virus, putting those who have not been vaccinated at risk of catching it.
The risk of vaccine-derived polio cases can be avoided by switching from using live oral polio vaccines (OPV) - which are highly effective, cheap and easy to deliver but contain live virus - to "inactivated" vaccines (IPV), which are not effective for fighting the wild type but contain no live virus.
WHO Regional Director Matshidiso Moeti said vaccine-derived cases like the ones in Central African Republic were less alarming than the wild type of the virus which still circulates in Pakistan and Afghanistan.
Africa's last case of wild polio was recorded in Nigeria in 2016, and three years on the country can begin the months of paperwork needed before declaring that the virus is no longer circulating there, Moeti told Reuters.
"We are hopeful that 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, and if Africa is declared free of the wild virus, health officials there will be able to switch to the inactive vaccine, removing the risk of more vaccine-derived cases too.
"That's the plan, that's the hope," Moeti said, adding that 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 the most vulnerable.
(Reporting by Tom Miles, editing by Ed Osmond)