A vaccine-derived polio virus was detected in Ghaziabad sewage, prompting a survey of 30,000 households to assess risks.
Health authorities in Ghaziabad have launched an extensive door-to-door survey covering nearly 30,000 households after a vaccine-derived poliovirus (VDPV) was detected in a sewage sample collected at the Vijay Nagar pumping station earlier this month. The large-scale public health exercise aims to identify vulnerable children, assess vaccination coverage, and prevent any potential spread of the virus.
The survey, which began earlier this week, has already covered 5,421 homes and identified 2,590 children under the age of five. According to news reports, officials say the Uttar Pradesh government is closely monitoring the operation, the National Centre for Disease Control (NCDC), and the World Health Organization (WHO).
What is the vaccine-derived polio virus?
Vaccine-derived poliovirus originates from the oral polio vaccine (OPV), which contains a weakened form of the poliovirus. After vaccination, the weakened virus can replicate in the intestine and may be excreted in stool for a short period.
In rare circumstances, particularly in areas where immunization rates are low, the weakened virus can continue circulating in the community long enough to genetically change and regain the ability to spread. This is known as vaccine-derived poliovirus (VDPV). According to the WHO, such cases are extremely rare and are generally associated with communities that have gaps in vaccination coverage.
Why was the virus found in Ghaziabad?
The virus was detected during routine environmental surveillance, a system that regularly tests sewage samples to identify poliovirus circulation before any human cases emerge.
Following the detection, authorities mapped the sewage drainage network connected to the Vijay Nagar pumping station and identified 12 localities that could potentially be affected. These include Vijay Nagar, Raj Nagar, Daulatpura, Panchvati Kot Village, Ghukna, Hindon Vihar, Kaila Bhatta, Mirzapur, Kharati Nagar, Bulandshahr, Shastri Nagar, and Vijay Nagar 2. Together, these areas are home to more than 1.5 lakh residents.
Officials have emphasized that the detected strain is largely non-virulent and remains contained. Similar detections have previously been reported in parts of Varanasi and Meghalaya without resulting in major outbreaks.
Is there a risk of polio returning to India?
India achieved a major public health milestone when the WHO certified the country as polio-free in 2014. The certification refers specifically to the elimination of wild poliovirus transmission.
However, health experts stress that continued surveillance remains essential because vaccine-derived strains can occasionally appear in environmental samples. Detecting the virus in sewage does not mean there is an active outbreak or confirmed cases of paralysis. The discovery instead highlights the effectiveness of India’s surveillance system, which is designed to identify potential threats early and respond quickly.