The Telangana government on Tuesday sounded an emergency after an active P2 strain of polio virus (vaccine-derived) was detected in a sample of water collected from a drain in Hyderabad's Amberpet area.
The Times of India reported that this prompted the state government to airlift two lakh vaccines from Geneva in a bid to inoculate more than three lakh children in Hyderabad and Ranga Reddy district as a "preventive measure" from Wednesday.
India completed five years as a polio free country in January this year as the last case was reported in 2011, as reported by the World Health Organization (WHO).
While a direct case of Polio has not been reported yet, the latest polio strain is the latest among many cases of Vaccine Derived Polio Virus (VDPV) strains, two of which were reported in 2014.
What is Vaccine Derived Polio Virus (VDPV)
The oral polio vaccine (OPV) is not unlike any other vaccine, and consists of small amount of the weakened virus, which stays in the intestine for a small period and helps the body develop immunity by building anti-bodies against the virus.
Following this, the vaccine-virus is excreted from the body.
The WHO states:
On rare occasions, if a population is seriously under-immunized, an excreted vaccine-virus can continue to circulate for an extended period of time. The longer it is allowed to survive, the more genetic changes it undergoes. In very rare instances, the vaccine-virus can genetically change into a form that can paralyse – this is what is known as a circulating vaccine-derived polio virus (VDPV).
However, the detection of a VDPV is still said to be a rare case.
How can VDPVs be stopped?
VDPVs can be stopped with two to three rounds of supplementary immunization. Every child under the age of five years in the area, can be immunized again with OPV to stop the transmission of VDPV.
The Telangana government is now embarking on a massive vaccination drive to prevent this virus from having an impact on children in the city.