Delhi conducted its fifth sero-prevalence survey in January and the results have revealed that the national capital is inching closer towards attaining herd immunity against Covid-19.
The latest sero-survey has found that every second person in Delhi has developed antibodies against the novel coronavirus. This means of the over two crore people residing in Delhi, nearly one crore people have already contracted Covid-19 and recovered from it.
[q]What is herd immunity?[/q]
[ans]Experts say herd immunity is said to have been developed in a population segment if 50-60 per cent of those are found to have the presence of antibodies in a seroprevalence survey.
Herd immunity implies that in any set of people in a community, after becoming affected by the virus, a lot many of them become immune to it, on account of antibodies developed in response to it. And, hence, such people become a protective layer between the infected person and unaffected people, thereby breaking the chain of viral transmission.[/ans]
[q]How many samples were collected?[/q]
[ans]This was the fifth sero-survey conducted in Delhi; it was kicked off on January 11 and 28,000 samples were collected during the exercise.[/ans]
[q]What did previous surveys say?[/q]
[ans]The first one was done in July 2020 and had revealed that 23 per cent of the surveyed population had developed antibodies against COVID-19. The previous serological survey conducted in Delhi in October had revealed that 25.5 percent of the population had COVID-19 antibodies. The September survey had shown sero-prevalence in 25.1 percent of the population, while the August survey had found antibodies in 29.1 percent of Delhi’s population.[/ans]
[q]What is the purpose of sero-survey?[/q]
[ans]Seroprevalance, or sero-surveys, helps understand the proportion of population exposed to SAR-CoV-2 infection including asymptomatic or individuals who do not show any signs of COVID-19. Depending on the level of sero-prevalence of the infection, appropriate public health interventions are planned and implemented for prevention and control of the disease. Periodic sero-surveys are useful to guide the policy makers.[/ans]