The serological survey conducted in Delhi has shown 23.48% of the participants with developed IgG (Immunoglobulin G) antibodies. This means they had been exposed to the coronavirus, the Union Health Ministry said today. The study indicated further that a large number of infected persons were asymptomatic.
“The results of the seroprevalence study show that on average, across Delhi, the prevalence of IgG antibodies is 23.48%. The study also indicates that a large number of infected persons remain asymptomatic. Nearly six months into the epidemic, only 23.48% 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,” the Ministry of Health and Family Welfare said in a statement.
The ministry said the results showed a significant proportion of the population 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.
A high-level expert committee led by NITI Aayog member Dr VK Paul, along with AIIMS Director Dr Randeep Guleria and some experts from NCDC and Delhi government, had taken the decision to perform a serological survey in Delhi.
The surveyors collected between 27 June and 10 July 21,387 samples from 11 districts to test for the presence of antibodies in the general population. They chose the subjects at random.
“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 experts in serological studies, antibody tests are not diagnostic. They check for antibodies that may have formed after the virus infects the individual. At present, Delhi is following RT-PCR and antigen testing for diagnosing the disease.