Vaccine-Derived Polio Strain in Morobe Province, Papua New Guinea

The Global Polio Eradication Initiative and the National Department of Health of Papua New Guinea have identified a case of paralysis due to a vaccine-derived strain of poliovirus called cVDPV1. The child was from Morobe Province. This strain was also identified in samples from two healthy children in the community, indicating that this strain is now circulating in the local population.

Consigli

These patients are not infected with the wild polio virus. A potential, but rare, adverse effect of the oral polio vaccine (OPV) is the ability to recombine to a form that may cause neurological infection and cause paralysis. This is believed to be a rare event, but outbreaks of vaccine-associated paralytic poliomyelitis, caused by a circulating vaccine-derived poliovirus (VDPV), have been reported. Circulating VDPVs occur when routine or supplementary immunization activities are poorly conducted and a population is left susceptible to poliovirus, whether from vaccine-derived or wild poliovirus. Hence, the problem is not with the vaccine itself, but low vaccination coverage. Outbreaks of paralysis due to the vaccine-derived strain tend to occur in areas where polio vaccination levels have not been maintained in the general population.

Travellers to any country that reports cases of polio (whether wild or vaccine-derived type) can reduce their risk of exposure to poliovirus by ensuring that their childhood vaccinations, including polio, are up-to-date prior to travelling. For added protection, travellers who are visiting countries where transmission of the polio virus is continuing should receive an additional dose of oral polio vaccine or inactivated polio vaccine within 4 weeks to 12 months before travelling.