Population based Seroprevalence of SARS-CoV-2 Specific IgG Antibodies in Rural Ahmedabad - A Case Control Study

Coronavirus disease (COVID-19) is an infectious disease caused by the most recently discovered coronavirus, Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2). The disease was declared as a Public Health Emergency of International Concern and later as a global pandemic by the World Health Organization. [1]Community serological surveys are aimed at estimating prevalence of infection in a given region and thereby guiding strategies to prevent its spread. They are based on detecting antibodies (generally the category called immunoglobulin G, or IgG) in the population of the region. The presence of antibodies in an individual is indicative of that person having had infection in the recent past (that is, 10-14 days ago). The estimate of the population share with antibodies (or the seropositivity rate) tells one the level of prevalence of infection in the region. Sero-surveys also tell one about the prevalence of asymptomatic infection in the region. The immune system mounts a defence against an infection by producing antibodies specifically against the invading pathogen, with the IgGs, in particular, lasting for fairly long. Recent studies on patients who recovered from COVID-19 suggest that IgGs against SARS-CoV-2 may last up to six to eight months. [2]Antibodies develop against different proteins that are part of the virus. Antibodies against one type of viral protein might neutralise the virus by blocking its entry into cells and preventing it from multiplying, while others might not.