Over 23% Delhiites have corona antibodies, sero-survey reveals

Six months into the coronavirus epidemic, 23.48 % of the people in densely-populated Delhi have developed anti-bodies for coronavirus, a study commissioned by the Union Ministry of Health and Family Welfare revealed on Tuesday.

The data came out in a sero-surveillance study by the National Centre for Disease Control in collaboration with the Delhi Government. The study was conducted from June 27 to July 10 in the city.

"The results of the sero-prevalence study show that on an average, across Delhi, the prevalence of IgG antibodies is 23.48 %. The study also indicates that a large number of infected persons remain asymptomatic," the ministry said in a statement.

The low percentage can be attributed to 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.

"However, a significant proportion of the population is still vulnerable. Therefore, the containment measures need to continue with the same rigour. Non-pharmacological interventions such as physical distancing, use of face masks or cover, hand hygiene, cough etiquette and avoidance of crowded places, etc., must be followed strictly," it added.

It is one of the largest sero-prevalence studies conducted in the country using the enzyme-linked immunosorbent assay (ELISA) testing.

For all the eleven 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 the Indian Council for Medical Research.

As many as 21,387 samples were collected as per the lab standards and were tested. The tests helped in the identification of the presence of antibodies in the general population.

This test is not a diagnostic test, but only provides information about past infection due to SARSCoV-2 in individuals who test positive.

Antibody testing repeatedly done over time, i.e., sero-surveillance, generates important evidence for assessing the spread of the pandemic from time to time.