Amidst concerns over wild polio virus (P2 strain) being found in a Hyderabad drain, the Union Health Ministry on Wednesday said it was a vaccine derived virus and does not change the polio-free status of India.
However, as a precautionary measure, the ministry will hold a special immunization drive in the high-risk areas of Telangana.
"India continues to be polio free as the country has eradicated wild polio virus and the last case was seen on January 13, 2011 and it is more than 5 years that no wild polio virus has been detected," it said in a statement.
The Health Ministry said the detected polio virus strain, which was was found in a sewage sample collected near the Secunderabad railway station, is vaccine derived polio virus (VDPV).
VDPV are rare strain of the polio viruses that have genetically mutated from the strain contained in the Oral Polio Vaccine (OPV).
The OPV contains live virus particles that get excreted by babies who are given the vaccine and gets into the sewage.
While the OPV protects children, these excreted virus particles can at times regain neurovirulence (the tendency or capacity of a microorganism to cause disease of the nervous system) including through contaminated drinking water, and can cause paralysis if consumed by humans.
"No children have been found to be affected by the detected VDPV isolate in the nearby areas. Last case of Wild Polio Virus Type 2 in country was reported 17 years back in 1999," the Ministry said.
The special campaign will be held from June 20 covering high-risk areas of Hyderabad and Rangareddy districts of Telangana, where an estimated 300,000 children will be protected against polio using Inactivated Polio Vaccine (IPV).
Under the special campaign, children between the age group of six weeks and three years will be given an additional dose of the injectable polio vaccine (IPV). Vaccination booths will be set up in the areas being covered in these campaigns.
"The special immunisation campaign will ensure all vulnerable children living in high-risk areas are given protection against polio," it said.
It said that a rapid surveillance review of the area revealed that the population immunity against polio type 2 is high as trivalent oral polio vaccine (tOPV) was in use in the state until 24 April and two mass vaccination campaigns were conducted in January and February.
"As per recent sample survey in the area, 94 per cent children were found to have received at least 3 doses of OPV.
Therefore, chances of its transmission in concerned area are unlikely," the ministry said.