Delhi sero-survey reported that on an average, across Delhi, the prevalence of IgG antibodies is 23.48 per cent. The study conducted by the National Center for Disease Control (NCDC)also indicates that a large number of infected persons remain asymptomatic.
The Union Ministry of Health and Family Welfare (MoHFW) commissioned a sero-surveillance study in Delhi. This study has been done by the NCDC in collaboration with the Government of National Capital Territory of Delhi, following a rigorous multi-stage sampling study design, a government statement said.
The study was conducted from June 27, 2020, to July 10, 2020.
A total of 21,387 samples were collected as per lab standards and were tested. The tests done help in 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 SARSCoV-2 in individuals who test positive, it added.
Antibody testing repeatedly was done over time i.e. sero-surveillance, generates important evidence for assessing the spread of the pandemic from time to time.
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 sero-prevalence studies conducted in the country using the ELISA testing.
Notably, the study also indicates that a large number of infected persons remain asymptomatic. This implies the following:
1. 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.
2. However, a significant proportion of the population is still vulnerable. Therefore, 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, must be followed strictly.