A serological survey conducted by the directorate of public health noted that 3 out of 10 people tested positive for SARS-CoV-2 antibodies as of November last year in the state of Tamil Nadu.

The data suggest that over 2.3 crore people in the state were infected with COVID-19 until November 2020.  This is around 36 times the actual number of people who officially tested positive for the disease. The data are not yet peer-reviewed.

This representative study was conducted in collaboration with scientists from the US from October through November and estimated the average sero-prevalence in the state as 31.5%. The sero-prevalence varied in different parts of Tamil Nadu, ranging from 11.1% in the Nilgiris to 51.05% in Perambalur district. Chennai was noted to have a sero-positivity of 40.9%, while Coimbatore had a sero-positivity of 20.4%, Trichy 32% and Madurai 38%... (ET Healthworld – TNN, February 10, 2021)