vaccine-derived-polio-virusvdpv

Context:

Though India has eradicated polio virus,cases of VPV are still seen.

About VDPV

  • In VDPV, the source of the virus is the vaccine itself. 
  • The oral polio vaccine called polio drops, which India deployed extensively to fight against polio, contain a live, attenuated or weakened polio virus
  • When a child is vaccinated, the weakened vaccine-virus replicates in the intestine and enters into the bloodstream, triggering a protective immune response in the child. 
  • Like wild poliovirus, the child excretes the vaccine-virus for a period of six to eight weeks.
  • Importantly, as it is excreted, some of the vaccine-virus may no longer be the same as the original vaccine-virus as it gets genetically altered during replication. 
  • In areas of inadequate sanitation, this excreted vaccine-virus can quickly spread in the community and infect children with low immunity.

About Polio

  • Poliomyelitis or polio is a highly infectious disease caused by a virus
  • It invades the nervous system, and causes paralysis, medically known as an acute flaccid paralysis (AFP), which is characterised by sudden muscle weakness and pain in the limbs. 
  • The disease is transmitted from person to person, mainly through the faecal-oral route, affecting children under five years of age. 
  • In the absence of wild polio virus (WPV) transmission, India was declared a polio-free country in March 2014, after years of relentless vaccination.

 

Inactivated Polio Vaccine(IPV) Vs Oral Polio Vaccine(OPV) 

IPV

OPV

IPV given through an injection contains inactivated virus, considered to be safer than OPV that contains live virus.

WHO has been advocating IPV over OPV as part of its global endgame strategy on polio eradication. 

OPV has its strong advocates who believe that the 

a.Vaccine is best suited for countries such as India due to its low cost, high efficacy and ease of administering,

b.The safety concerns are overstated compared to the benefits of the vaccine.