WHO’s Polio Case Database: Containing More Than It Discloses

• The World Health Organization (WHO) polio case database only reports circulating vaccine-derived poliovirus (VDPV) cases, not all vaccine-associated paralytic polio (VAPP) cases.

• The WHO registry does not report all categories of VDPV cases, including circulating VDPV cases, immune-deficiency associated VDPV (iVDPV), and ambiguous vaccine-derived polioviruses (aVDPVs).

• The Global Polio Eradication Initiative (GPEI) registry also has data on only circulating VDPVs and not the other two VDPV categories.

• The GPEI registry maintains a registry of iVDPV cases, but the data of iVDPV cases in the GPEI registry is not made publicly available.

• The WHO should have the same data as all WHO-accredited polio laboratories, which confirm both wild poliovirus and VDPV cases and classify the VDPV cases into one of the three categories.

• The risks posed by iVDPV strains and their prevalence globally are unknown, making their relevance in the context of the GPEI endgame difficult to assess.

• WHO is aware that iVDPV cases serve as potential reservoirs for neurovirulent VDPV strains and can pose a significant threat to the eradication campaign