Vaccine-derived polio

About Vaccine-derived poliovirus:

• It is a documented variant of poliovirus that originates from the strain used in the oral polio vaccine (OPV). 
• The OPV includes a live, weakened poliovirus that temporarily replicates in the intestine, stimulating the immune system to produce antibodies and develop immunity.
• 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.
• Available vaccines:
  • Oral Polio Vaccine (OPV): Administered as a birth dose, followed by three primary doses at 6, 10, and 14 weeks, and a booster dose at 16-24 months.
  • Injectable Polio Vaccine (IPV): This vaccine is given as an additional dose along with the third DPT (Diphtheria, Pertussis, and Tetanus) vaccine under the Universal Immunization Programme (UIP).

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.

Q1. What is a vaccine?

A vaccine is a biological preparation that stimulates the body’s immune response to specific diseases. It can be administered via needle injections, orally, or as a nasal spray, helping the immune system recognize and fight pathogens effectively.

Source: Centre says Meghalaya polio case is vaccine-derived - The Hindu