NCDC is under administrative control of the Directorate General of Health Services in the Union Ministry of Health and Family Welfare.
Detects Specific Antibodies: It seeks to assess the prevalence of disease in a population by detecting the presence of specific antibodies against the virus.
Immunity Check: It can also be conducted to check if a person has developed immunity to certain diseases.
Past Infections: It indicates past infections (and which triggered an immune response), and is not used to detect active infections.
Tested Immunoglobulin G Using ELISA: The Sera (a part of blood) of samples were tested for IgG antibodies and Covid-19 infection using Covid Kavach ELISA kits approved by the Indian Council of Medical Research (ICMR).
IgG (Immunoglobulin G) is a type of antibody which develops in most Covid-19 patients (infections) at around two weeks after infection and remains in the blood even after recovery.
ELISA (Enzyme-Linked Immunosorbent Assay) is a test that detects and measures antibodies in blood
Coverage of the Latest Study:
Coverage Period: It was conducted from 27th June - 10th July 2020. It was done when the city was reporting over 3,000 cases a day.
Coverage Groups: A total 21,387 samples were randomly collected across the 11 districts of the capital, which were then divided into two groups, of less than 18 years and older.
23.48% of the people surveyed had developed IgG antibodies, indicating they had been exposed to the novel coronavirus (SARS-CoV-2) that causes Covid-19, with a large number showing no symptoms (asymptomatic).
Impact of Proactive Efforts: Only 23.48% were found to be infected in a study carried out in a city with several pockets of dense population, shows that the proactive efforts by the government to prevent the spread of Covid-19, including prompt lockdown, effective containment and surveillance measures, contact tracing and tracking, as well as citizens’ compliance had yielded benefits.
Challenges: The remaining proportion of the population (about 77%) is still vulnerable to contracting the novel coronavirus infection.
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.
The 23.48% rate of seropositivity cannot be extrapolated over Delhi’s entire population.
Further, currently there isn’t enough scientific data available about the level and duration of immunity that the body will develop after a person tests Covid-positive.
Sero-surveillance in the Past:
ICMR had conducted a pilot sero-survey in April 2020 across 83 districts in 21 states.
The initial results, which are being peer-reviewed, suggested that the percentage of the general population that could have been infected was 0.73, with urban areas showing a higher prevalence of about 1.09%.
The robust data collected through the study will help in the disease control programme.
Such scientific studies are extremely important and should be performed from time to time to understand the lessons from the past.