Third serological survey in Delhi from Sept 1 to 5

The second survey was done between August 1 and 7 and antibodies were found among 29.1% of people surveyed

The third serological survey in Delhi will be held between September 1 and 5 and around 17,000 people are expected to be surveyed, officials aware of the matter said on Tuesday.

A medical personnel with vials of blood samples taken during a serological survey earlier in August. (Sanchit Khanna/HT PHOTO)

“Samples will be collected from all the 11 districts of Delhi and across all age groups. Around 17,000 samples will be collected,” said a health department official, who did not want to be named.

The number of samples to be collected will be more than the second serological survey. They will lesser than those collected for the first survey led by the National Centre for Disease Control.

The first survey was held between June 27 and July 10 during which 22.86% of people were found to have developed antibodies against Sars-CoV-2 that causes Covid-19. The second survey was done between August 1 and 7 and antibodies were found among 29.1% of people surveyed.

In the first survey, samples were collected from 21,387 people and in the second from 15,000. The second survey showed a prevalence of antibodies among women in Delhi was more (32.2%) when compared to men (28.3%).

According to the second survey report, the prevalence of antibodies among those aged less than 18 were found to be 34.7%, those between 18-50 28.5% and those above 50 31.2%.

Officials said even if the third survey finds the prevalence of antibodies in around 35% of Delhi’s population, the Covid-19 management strategies would largely remain unchanged.

“Whether there is a high prevalence of antibodies in one district and lower in another, both cases would need the same strategy of the test, track, and treat. Active surveillance and contact tracing will have to continue and high-risk group and special surveillance groups will have to be checked on frequently,” said a health official, who did not want to be named.

The Covid-19 positivity rate has started rising again in Delhi. As many as 7.4% of all tests conducted in the last week came positive, the highest in over a month, suggesting that Delhi may be facing a fresh challenge to control the outbreak it had contained to a considerable extent.

The positivity rate is a crucial metric as experts say it shows how widespread the virus is in the community, and when coupled with an increase in new cases, it indicates that the virus is spreading fast.

The national capital reported 1,061 cases and 13 deaths as per Monday’s Covid-19 bulletin, taking the total number of infections in the city to 162,527 and fatalities to 4,313.

Dr. Lalit Kant, a former head of epidemiology at the Indian Council of Medical Research, said Delhi’s positivity rate has once again started to gradually increase which means the infection is still spreading in the city.

“At this juncture, Delhi cannot be complacent. Testing numbers should not decline. More and more testing is the key to managing Covid-19 and the mode of testing should preferably be RT-PCR [reverse transcription-polymerase chain reaction],” he said.