90% in Delhi have COVID-19 antibodies. What does it mean?
The results of the sixth serological survey conducted in Delhi reveal that more than 90% people in the national capital have developed antibodies against the coronavirus. Every district of the city registered at least 85% sero-positivity. This was Delhi's first sero-survey carried out after the devastating second wave of the pandemic earlier this year. Here's what it means.
What is a sero-survey?
When a person is exposed to an infection, their body develops antibodies to fight against it. While the infection disappears in some weeks, the antibodies remain for a longer period of time. A sero-survey is done to find out the prevalence of a disease in a community. Samples of serum, a liquid part of the blood, are taken from the participants for the survey.
When was this sero-survey done?
Sample collection for the latest round of sero-survey had started in Delhi on September 24. For a week, nearly 28,000 samples were collected from 280 wards of the city. The findings reveal that more women were found sero-positive as compared to men. In the fifth round of sero-survey done in January, 56.13% of the people in Delhi had developed COVID-19 antibodies.
What are its implications?
The high level of sero-positivity indicates that Delhi is unlikely to witness another COVID-19 outbreak as severe as the one seen earlier this year. However, that may happen in case a new, severe COVID-19 variant emerges in future, according to officials. The figure also signifies the success of the city's vaccination program which has gained pace in the recent months after some early snags.
Has Delhi achieved herd immunity?
Herd immunity is when enough number of people have developed immunity that a virus/disease fails to spread. Officials, however, say it cannot be concluded that Delhi has achieved that. "We cannot say exactly if Delhi has achieved herd immunity because there are no studies or data to show that the virus won't spread after a certain percentage of population is affected," an official said.
How is the COVID-19 situation in Delhi?
Delhi has seen a significant improvement in its COVID-19 situation following a devastating outbreak in April-May this year. Daily cases in the city have remained under 100 since August. Further, there have been no deaths due to the disease for five straight days. The positivity rate in Delhi has remained under 0.1%. Meanwhile, 48% of residents have been fully vaccinated against COVID-19.