After a test to identify Covid-19 antibodies in a randomly chosen sample of 21,387 across Delhi’s 11 districts shows that almost one in every four residents of the city has antibodies, indicating exposure to the virus , the Delhi government said it will consult medical experts to assess whether the Capital needs a change in its Covid-19 strategy.
Antibody tests are conducted to assess prevalence; the presence of antibodies in people indicates that they have at least short-term immunity against the disease. The survey, conducted in Delhi between June 27 and July 10, was aimed to determine the extent of the coronavirus disease (Covid-19)’s spread in the city. Interestingly, the number of daily new cases in Delhi started declining from around the end of June and at least some experts believe that the worst is behind the Capital.
Responding to the survey results released by the Union ministry of health and family welfare on Tuesday, the Delhi government said the Covid-19 situation in the Capital has improved . It said the daily new cases now have come down to around 1,300 and that at the time of the survey, more than 2,000 new cases were being added every day.
“The results of the sero-prevalence study conducted by NCDC in Delhi show that on an average, across Delhi, the prevalence of IgG (Immunoglobulin G) antibodies is 23.48% in the population. This captures the state of recovery from Covid-19 infection in mid-June, which is a month ago. We will consult with public health experts and epidemiologists to determine if the future course of Delhi’s strategy against Covid-19 should change in light of these survey results or not,” Delhi chief minister Arvind Kejriwal’s office said in a statement.
To be sure, the 23.48% prevalence is still lower than the 60% or 43% required for herd immunity (based on various studies). When a certain proportion of the population is exposed to the virus and has antibodies, the infection can’t travel very far before encountering someone immune to it — thereby breaking the chain. This is called herd immunity.
The government’s current Covid-19 strategy is focused on testing and isolating. Delhi has tested 43,708 people per million of its population till Tuesday as per the delhifightscorona web portal. These tests are a combination of RT-PCR confirmatory tests, rapid antigen tests which are quicker in terms of its results but are non-confirmatory and CBNAAT and TrueNAT tests.