Covid-19 prevalence among adults increased 10 times in last three months: ICMR sero-survey

The prevalence of Covid-19 among Indian adults has increased by nearly 10 times in the last three months, signalling exposure to the novel coronavirus by crores of people even though the majority of them did not contract the disease.

The results of the Indian Council of Medical Research’s (ICMR) second serological survey showed more than nine crore Indians aged 10 years and above were exposed to the virus as Covid-19-specific antibodies were found in their blood.

When compared with the first sero-survey, the jump is 10 times. Carried out between May 11 and June 10, the first survey presented a prevalence figure of 0.73% whereas the second survey conducted between August 17 and September 22 threw up a figure of 7.1% prevalence among adults — a tenfold rise.

Not to miss out on children, ICMR and health ministry researchers this time expanded the surveillance net to include individuals aged 10 years and above. With their inclusion, the prevalence was 6.6%.

When estimated on the base of India’s 138 crore population, this means over nine crore Indians were exposed to the novel coronavirus but the total Covid-19 cases stands at only 61 lakh plus.

"In a pandemic situation, you can never identify every asymptomatic individual. The purpose of a sero-survey is to reconcile and plan for the future,” said Vinod Paul, NITI Aayog member and a former professor at the All India Institute of Medical Sciences.

The second survey relied on blood samples taken from 29,082 people from the same 700 villages in the same 70 districts in 21 states that were covered in the first round.

“The results show susceptibility of a considerable section of people, yet unexposed to SARS-Cov-2, exists. The risk in urban slums (15.6%) is twice than that in non-slum areas (8.2%) and four times than the risk in rural (4.4%),” ICMR director general Balram Bhargava said at a press conference.

The survey results show that for every reported case in August, there were 26-32 infections that escaped the testing net. But the number of such unreported cases was 81-130 in May, signifying a decline, which the government officials said was due to the effect of scaled-up testing, tracking and treating strategy.

“The survey is very important to understand the trajectory of the pandemic. The case to infection ratio has dropped nearly three times, suggesting there has been a significant improvement in the testing rates in the country,” Giridhar Babu, an epidemiologist at the Public Health Foundation of India, told DH.

The national prevalence is much less than what has been reported from a few states, but it is similar to the prevalence seen in the USA, Brazil and Spain.

For the first time in September, India’s daily Covid-19 toll fell below 1,000 with the reporting of 776 deaths on Monday. The total death count stands at 96,318 as per the official estimate. The number of active cases stands at 9.47 lakh, out of which 70,589 new cases were added in the last 24 hours.