The Ministry of Health and Family Welfare [MoHFW] commissioned a sero-surveillance study in Delhi.
This study has been done by the National Center for Disease Control [ NCDC] in collaboration with Govt of National Capital Territory of Delhi, following a rigorous multi-stage sampling study design.
The study was conducted from the 27th of June 2020 to 10th July 2020.
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.
21,387 samples were collected as per lab standards and were tested. The tests did help in the identification of the presence of antibodies in the general population. These test performed is not a diagnostic test but only provides information about past infection due to SARS-CoV-2 in individuals who test positive.
Antibody testing repeatedly was done over time i.e. sero-surveillance, which generates important evidence for assessing the spread of the pandemic from time to time.
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. This implies the following:
- 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 compliance to COVID Appropriate Behaviours.
- However, a significant proportion of the population is still vulnerable. Therefore, containment measures need to continue with the same rigor. 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.