Sero survey hints at high infection rate

NEWDELHI: Around 15% of Delhi’s population appears to have been infected with the coronavirus disease (Covid-19), with the rate much higher in some pockets, according to initial results of antibody testing of 22,823 people across the Capital.

The overall trend of a Delhispecific sero surveillance, conducted by the National Centre for Disease Control and Delhi government across 11 districts between June 27 and July 5, suggests that certain pockets have developed widespread transmission but are still amenable to containment, according to government officials familiar with the findings of the report.

The interim findings are higher than the national average of positivity rate— around 10%.

To be sure, health experts have said that many people around the world may have had Covid-19 (and since recovered) without realising it because they suffered very mild symptoms. A similar survey in New York, for instance, suggested that nearly 14% of the population had been infected by the virus and recovered.

“Interim data indicates the average cross-sectional prevalence looks to be around 15%, which has even gone up to 25% in a few zones. The entire data is not out yet so there may be some variation in the final result, but the overall the trend suggests certain pockets have developed widespread transmission that is still amenable to containment,” the official cited above said, requesting not to be identified.

In a serological surveillance, or sero survey, blood serum of a group of individuals is tested in order to understand the prevalence of a virus in that region.

The final result of pilot sero survey done by the Indian Council of Medical Research (ICMR) across 21 states in April is also being processed, and the research body is preparing to launch a follow-up sero survey soon, officials said.