The Global Polio Eradication Initiative (GPEI) said yesterday that newly detected cases of vaccine-derived polio in the Democratic Republic of the Congo (DRC) and Burundi appear to be linked to the novel oral polio vaccine type 2 (nOPV2).
GPEI said isolates of vaccine-derived poliovirus type 2 (cVDPV2) were detected in stool samples of six children with acute flaccid paralysis in DRC and one in Burundi. The virus was also isolated from five environmental samples in Burundi. All the reported isolates stem from two separate and new emergences of cVDPV2 linked with nOPV2 that originated in Tanganyika and South Kivu provinces in DRC.
Close to 600 million doses of nOPV2 have been administered in 28 countries since rollout of the vaccine began in March 2021. GPEI said these are the first two instances of cVDPV2 linked to the vaccine.
"While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine," the organization said in a statement. "All available clinical and field evidence continues to demonstrate that nOPV2 is safe and effective and has a significantly lower risk of reverting to a form that cause paralysis in low immunity settings when compared to monovalent oral polio vaccine type 2."
In a news release today, the World Health Organization (WHO) said cVDPV2 has been confirmed in two additional children in Burundi, leading the government to declare an outbreak.
While detection of these outbreaks is a tragedy for the families and communities affected, it is not unexpected with wider use of the vaccine.
Authorities in both countries, with assistance from the WHO and GPEI, are investigating the cases, have stepped up polio surveillance in the areas of detection, and will launch initial vaccination campaigns in April. Subsequent campaigns may be expanded to include parts of neighboring countries.
The polio cases in DRC and Burundi were among those reported by GPEI in its most recent polio update. Detection of cVDPV2 was also reported in Chad (two cases), Niger (one), and Benin (one). Wild poliovirus type 1 was detected in an environmental sample in Pakistan.