iVDPVs

iVDPVs, or immunodeficiency-associated vaccine-derived polioviruses, are poliovirus strains that originate from the oral polio vaccine (OPV) and are excreted by individuals with primary immunodeficiencies. In people with immune system disorders, the attenuated vaccine virus can replicate for extended periods, accumulate mutations, and gradually revert toward a neurovirulent form. This set of viruses is distinguished from circulating vaccine-derived polioviruses by its association with a known immunodeficiency rather than spread in a community.

iVDPVs can arise from any of the three poliovirus serotypes and have been detected in various countries. The duration of shedding varies widely, with some individuals excreting virus for months and, in rare cases, for years. Because these viruses can accumulate mutations over time, they may become genetically distinct from the original Sabin vaccine strains.

Detection and surveillance rely on stool testing of individuals with immunodeficiencies and on broader poliovirus monitoring, including environmental sampling. Genomic sequencing is used to characterize divergence from Sabin strains and to understand the evolution of the excreted virus.

Public health implications center on polio eradication goals and vaccine policy. iVDPVs highlight the risks associated with OPV in the presence of immunodeficiencies and the importance of high vaccination coverage with inactivated polio vaccine (IPV) to reduce transmission. Management of iVDPV infections includes preventing spread, providing medical care for the underlying immunodeficiency, and exploring antiviral options such as poliovirus antivirals where available. Ongoing surveillance and research are essential to mitigate risks posed by long-term excretion and potential transmission.