Besides wild poliovirus cases, the WHO registry has data of only the circulating VDPV cases and not the cases that belong to the other two VDPV categories — iVDPV and aVDPV
On June 17, 2022, WHO published a report of a VDPV type-1 case that was detected from an environmental sewage sample in Kolkata on April 25, 2022. The report said that genetic sequencing “established that it was not related to any of the previously identified VDPV1 viruses and was likely to be iVDPV (excreted from an immune-deficient individual)”. But nearly three months after the results of the Meghalaya polio case was shared with the WHO on August 12, and more than one-a-half-months after the follow-up results confirmed that the immunological profile of the child was normal and that there was no evidence that the virus was circulating in the community, WHO is yet to publish the details.
If the failure or delay by WHO in publishing the case details is puzzling, it has now come to light that besides not reporting vaccine-associated paralytic polio (VAPP) cases, the WHO registry does not report all categories of vaccine-derived poliovirus (VDPV) cases either. WHO classifies VDPV cases into: 1) circulating vaccine-derived polioviruses (cVDPVs), 2) immune-deficiency associated VDPV (iVDPV), and 3) ambiguous vaccine-derived polioviruses (aVDPVs). However, besides wild poliovirus cases, the WHO registry has data of only the circulating VDPV cases and not the cases that belong to the other two categories — iVDPV and aVDPV. In fact, the registry does not even list the other two VDPV categories, namely the iVDPV and ambiguous VDPV. Even in the case of the circulating VDPV cases, the WHO registry does not classify the cases based on poliovirus serotypes — type-1, type-2 or type-3.