Doctors wearing PPE kit at LNJP Hospital in New Delhi.
The serological survey conducted in Delhi has shown that 23.48 per cent of the people surveyed had developed IgG (Immunoglobulin G) antibodies, indicating they had been exposed to the coronavirus, the Union Health Ministry Tuesday said. The study also indicated that a large number of infected persons remain asymptomatic.
“The results of the sero-prevalence study show that on average, across Delhi, the prevalence of IgG antibodies is 23.48 per cent. The study also indicates that a large number of infected persons remain asymptomatic. Nearly six months into the epidemic, only 23.48 per cent of the people are affected in Delhi, which has several pockets of dense population. This can be attributed to the proactive efforts taken by the government to prevent the spread of infection including prompt lockdown, effective containment and surveillance measures, including contact tracing and tracking, as well as citizen’s compliance to Covid appropriate behaviours,” a statement issued by the Ministry of Health and Family Welfare said.
The ministry also said the results show that a significant proportion of the population is still vulnerable to the virus. “Containment measures need to continue with the same rigour. Non-pharmacological interventions such as physical distancing, use of face mask/cover, hand hygiene, cough etiquette and avoidance of crowded places, etc., must be followed strictly,” it said.
As part of the survey, which was conducted between June 27 and July 10, 21,387 samples were collected from 11 districts to test for the presence of antibodies in the general population. The subjects were chosen at random. The decision to perform a serological survey in Delhi was taken by a high-level expert committee led by NITI Aayog member Dr V K Paul along with AIIMS Director Dr Randeep Guleria and some experts from NCDC and Delhi government.
“For all the 11 districts of Delhi, survey teams were formed. Blood samples were collected from selected individuals after taking written informed consent and then their sera were tested for IgG antibodies and infection using COVID KAVACH ELISA approved by Indian Council for Medical Research (ICMR). It is one of the largest seroprevalence studies conducted in the country using the ELISA testing,” the statement said.
According to the experts, antibody tests are not diagnostic but check for antibodies that may have formed after the individual has been infected. At present, Delhi is following RT-PCR and antigen testing for diagnosing the disease.