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(THE GIST OF PIB) Vaccine-Derived Polio

(AUGUST-2024)

Vaccine-Derived Polio

Recently, a vaccine-derived polio case has been confirmed in a two-year-old child from Tikrikilla, Meghalaya. Health authorities clarified that this is not wild poliovirus but an infection seen in individuals with low immunity.

India’s polio-free status: India was declared polio-free by the World Health Organization (WHO) in 2014, with the last wild poliovirus case reported in 2011.

Understanding Vaccine-Derived Polio (VDPV)

Vaccine composition: The Oral Polio Vaccine (OPV) contains a weakened form of the poliovirus, which stimulates an immune response.
cVDPV development: On rare occasions, in under-immunized populations, the excreted vaccine virus can circulate, undergo genetic changes, and potentially revert to a form capable of causing paralysis. This is known as circulating vaccine-derived poliovirus (cVDPV).
Global context: Since 2000, over 10 billion doses of OPV have been administered globally, resulting in 24 cVDPV outbreaks in 21 countries, with fewer than 760 cases.
Prevention: To stop cVDPV transmission, WHO recommends multiple rounds of high-quality immunisation campaigns.

Key Facts about Polio:

Polio overview: Polio is a viral infectious disease that can cause irreversible paralysis and even death by affecting the nervous system.

Wild Poliovirus strains: There are three distinct strains of wild poliovirus:

Wild Poliovirus Type 1 (WPV1)
Wild Poliovirus Type 2 (WPV2)
Wild Poliovirus Type 3 (WPV3)
Although symptomatically similar, each strain has genetic and virological differences, necessitating separate eradication efforts.
Transmission: The virus primarily spreads through the fecal-oral route and can multiply in the intestine, where it can invade the nervous system. It predominantly affects children under five.