The World Health Organisation (WHO), yesterday, warned that Nigeria risks re-emergence of polio due to high incidence of circulating Vaccine Derived Polio Virus Type 2 (cVDPV2).
As the last polio-endemic country in Africa, the most populous black nation was officially certified free of the disease on August 25, 2020.
WHO’s Director General, Dr. Tedros Adhanom Ghebreyesus, in a statement, said Nigeria’s situation also presents a risk to neigbouring countries.
He had on February 28 this year convened the 31st meeting of the Emergency Committee under the International Health Regulations (2005) (IHR) on the global spread of poliovirus.
According to the statement, the total number of cVDPV2 cases in 2021 is 614, of which 413 occurred in Nigeria – considerably less than the 1,079 cases in 2020.
As in all the years following 2016 when Sabin-strain oral polio vaccine Type 2 (OPV2) was withdrawn, the number of cVDPV2 cases globally has been greater than the number of Wild Polio Virus Type 1 (WPV1) cases.
WPV2 was last observed in 1999. The OPV2 was critical to eradication, but it is known to revert to a neurovirulent phenotype, causing vaccine-associated paralytic poliomyelitis. OPV2 is also transmissible and can establish circulating lineages called circulating vaccine-derived polioviruses (cVDPVs), which can also cause paralytic outbreaks. Thus, in April 2016, OPV2 was removed from immunisation activities worldwide. Interrupting transmission of cVDPV2 lineages that survive cessation will require OPV2 in outbreak response, which risks seeding new cVDPVs.
The committee said based on analysis of genetic linkages among viruses, cross border spread continues to occur, with spread from Nigeria into Cameroun, Central African Republic (CAR), Chad and Niger and from Yemen into Djibouti and Egypt. Despite the ongoing decline in the number of cases and lineages, the risk of international spread of cVDPV2 remains high.
Executive Director/Chief Executive Officer (CEO), National Primary Health Care Development Agency (NPHCDA), Dr. Faisal Shuaib, said following the recent outbreak of WPV in Malawi, the Federal Government has put measures in place to safeguard the country against importation of the virus.
One of the measures, Shuaib said, is the reactivation and reconstitution of the Expert Review Committee on Polio Eradication and Routine Immunization (ERC).
