Polio Outbreak Declared in Papua New Guinea After Vaccine-Derived Virus Detected in Healthy Children

Papua New Guinea (PNG) is grappling with its first polio outbreak since 2018 after circulating vaccine-derived poliovirus type 2 (cVDPV2) was detected in two asymptomatic children in Lae, Morobe Province. The World Health Organization (WHO) confirmed the outbreak on 9 May 2025, triggering a national emergency response to curb potential spread in a country where vaccination rates remain critically low.

The Polio Outbreak: Detection and Origin

The virus was identified in stool samples from two healthy children during routine surveillance linked to an environmental sample collected in Lae on 4 April 2025. Genetic sequencing revealed the strain is closely related to a cVDPV2 lineage circulating in Indonesia since 2022, highlighting cross-border transmission risks. Wastewater testing in Lae and Port Moresby also confirmed the virus’s presence, indicating broader community transmission

Why Vaccine-Derived Polio?

cVDPV2 emerges when weakened poliovirus from oral polio vaccines (OPV) mutates in under-immunized communities. In areas with poor sanitation and low vaccination coverage, these strains can regain virulence, causing paralysis in rare cases. PNG’s national OPV3 coverage stands at just 44%, with Morobe Province reporting rates as low as 28–37% over the past five years. Some districts have immunization rates below 10%, leaving vast immunity gaps.

Public Health Response

The PNG government, supported by WHO, UNICEF, and Australia, has activated its Polio Preparedness and Immunization Response Plan. There are various key measures being taken. First of which is nationwide Vaccination Campaigns. Two rounds of mass immunization targeting 3.5 million children under 10, using the novel oral polio vaccine (nOPV2). It is because it is less prone to mutation. Second turns to enhanced surveillance, where increased testing for acute flaccid paralysis (AFP) has been proposed. There is a requirement for expanded environmental monitoring, including doubling wastewater sampling frequency in Lae. The third measure speaks about community engagement. The local leaders and churches are mobilized to combat vaccine hesitancy and misinformation, particularly in remote regions.