UNICEF released a statement on Tuesday correcting an October 21 report by its office in Madagascar “expressing concern over a resurgence of polio in Madagascar after a routine health survey identified vaccine-derived poliovirus (VDPV) in several healthy children.” According to the statement, “there was no re-emergence of polio in Madagascar,” and “[t]he last wild poliovirus case in Madagascar was detected in 1997.”

“A vaccine-derived poliovirus is a mutation of the virus that is present in the vaccine and in extremely rare instances can cause the disease it is meant to prevent,” the statement says, adding, “In Madagascar, none of the children from whom the [VDPV] was isolated had paralysis” (10/25). “UNICEF officials said an investigation had been launched to see why the three children had the vaccine-derived poliovirus. They said low immunity on the island could be the reason,” BBC News writes in a follow-up story to its previous report (10/25).