State’s health arm has been put on alert after vaccine-related polio virus was found in sewage collected from Amberpet.
Samples obtained from the Amberpet Sewage Treatment Plant about two weeks ago tested positive for polio at Enterovirus Research Centre in Mumbai, centre’s nodal agency that works on enteroviruses like polio. The lab found Type-2 vaccine-derived polio virus. Environmental testing for the virus began after April 24 this year, when India made the switch to bivalent polio vaccine from trivalent vaccine being administered earlier as mandated by the World Health Organisation (WHO) in its Polio Eradication and Endgame Strategic Plan.
Bivalent oral vaccines do not contain Type-2 polio virus, the variant blamed for vaccine-derived polio infections in India. Oral Polio Vaccines use weakened but live viruses to induce immunity. There is a very small chance that the virus in the vaccine can mutate over time and cause infections within a community. To prevent such vaccine-derived infections, the WHO recommended the switch from trivalent to bivalent vaccine. Finding the virus in the city’s sewerage nearly a month after India made the switch, raises many questions.
“It is possible the virus has been circulating in the sewerage for long. Amberpet is now being monitored and additional samples have been collected for testing,” said Amarender Reddy, Director for State’s Institute of Preventive Health that collects sewage samples for testing from three other locations in the city, including Attapur and Nagole. Recent results are the first instance of the city’s sewage showing polio presence. Dr. Reddy did not rule out the possibility of vaccines being disposed off in drains.
The WHO’s data keeping shows the last vaccine-derived infection in India occurred in 2010, but one case from Kolkata was reported last December. The vaccine-derived viruses spread and infect humans similar to wild polio viruses, which were eradicated from the country years ago. India was declared polio free in March 2014.
While asserting there was no cause for concern, Rajeshwari Tiwari, Telangana’s Principal Secretary for Health, Medical and Family Welfare, announced that a special polio vaccination campaign will begin from June 20 to 26 in Hyderabad and some parts of adjoining Ranga Reddy district.
