The second serological survey conducted in Delhi between August 1 and 7 has found that 29.1 per cent of the city’s population has developed antibodies against the coronavirus disease (COVID-19). Sero-surveillance with regard to COVID-19 means monitoring the presence or absence of SARS-CoV-2 virus-specific antibodies in the blood serum among the population.
The survey results also showed the prevalence of antibodies among women was more (32.2%) compared to men (28.3%).
Medical experts stated that the survey helps in understanding the burden of this disease better, given around 80 per cent of cases are asymptomatic and mild in nature.
While speaking on the importance of sero-surveillance Dr Neeraj Nishchal, Associate professor, department of medicine, AIIMS (New Delhi) told news agency ANI, "Sero-surveillance is measuring antibodies against any particular disease. COVID-19 is a new disease so the idea of actually how many have got infected because of this virus needs to be seen. The idea is to check the exact burden. This will further decide the strategy of containing/ mitigating the disease."
"The idea of sero-surveillance is to just check the antibody, so it will depend on the type of kit being used and whether it has been validated or not. The proven methods of avoiding this infection such as using face masks, social distancing, cough etiquettes becomes very important and that should be continued religiously," said Dr Nischal.
The government of the National Capital Territory of Delhi had commissioned a follow-up sero-survey for evaluation of the prevalence and trends of the SARS-CoV-2 infection in the general population of Delhi. The survey was planned by the Government of NCT Delhi with technical support of Maulana Azad Medical College (MAMC), New Delhi.
Dr Sheeba Marwah, Assistant Professor & COVID-19 Nodal Officer, Department of Obstetrics & Gynaecology, VMMC & Safdarjung Hospital said, "One of the loopholes of this test is that IgG antibodies develop after 14 days of viral infection only and also stay in our body for six to eight weeks maximum as per many recent studies and reviews from the west. This test determines a past infection in the last three months' time."
However, Dr Marwah also stated, "There is a lack of concrete evidence on whether having antibodies means you're protected against reinfection with COVID-19. The level of immunity and how long immunity lasts are not yet known."
The findings of the second survey show that the prevalence of antibodies among the people has increased by over 6 percentage points when compared to the first survey held between June 27 and July 10. As many as 22.86% of people were earlier found to have developed antibodies against Sars-CoV-2 that causes Covid-19. In the first survey, samples were collected from 21,387 people, whereas, in the second round, 15,000 samples were collected. Jain said the third round of the survey will begin from September 1 and would go on for a similar duration as earlier.
According to the second survey, prevalence of antibodies among those aged less than 18 was 34.7%, and 28.5% for those between 18-50. For those above 50, it was 31.2%.
(With ANI inputs)