New Vaccine-derived Polio Cases Confirmed

The last report of the Polio Eradication Initiative (GPEI) confirmed additional vaccine-derived poliovirus type 2 (cVDPV2) cases.

The west African country of the Islamic Republic of Mauritania confirmed its first cVDPV2 case in Nouakchott Nord, the first one in 2023.

And Indonesia's confirmed one cVDPV2 case was reported this week in Jawa Tengah. There have been four cVDPV2 cases this year and one case in 2022.

Indonesia Ministry of Health previously completed two rounds of immunization for children below five years of age with the nOPV2 vaccine, regardless of their prior vaccination status. The first round was implemented in April 2023.

The nOPV2 vaccine is a modified version of the type 2 monovalent OPV and is genetically more stable.

The administrative coverage of the bivalent oral polio vaccine between 2018 and 2022 in West Java ranged from 88% to 102%, while coverage of inactivated polio vaccine ranged from 26% to 106%. 

Vaccine-derived poliovirus is a strain mutated from the strain initially contained in the oral polio vaccine (OPV).

OPV vaccines contain a live, weakened form of poliovirus that replicates in the intestine for a limited period, thereby developing immunity by building up antibodies, says the World Health Organization (WHO).

On rare occasions, when replicating in the gastrointestinal tract, OPV strains genetically change and may spread in communities not fully vaccinated against polio.

According to the GPEI's data, as of December 31, 2023, about 1 billion nOPV2 vaccinations have been completed globally.

WHO's International Travel recommendations include .... that all travelers to the 35 polio-affected areas should be fully vaccinated against polio.