As the threat of a new wave of Covid looms over the country, the results of the latest Sero survey conducted in Tamil Nadu may offer a breather for the people in the State.
Protective levels of immunity against Covid was found to be at 97 per cent, as per a recent Sero Survey. Samples were tested for SARS-CoV-2 IgG (antibodies) and it revealed a 97 per cent presence of antibodies, according to the Directorate of Public Health and Preventive Medicine, Tamil Nadu.
This is the fifth phase of the survey. Phase-I was done in October 2020 and it was found that 32 per cent of people had Covid antibodies. Phase-II (April 2021) found 29 per cent, Phase-III (Aug 2021) found 70 per cent and Phase-IV (Dec 2021) recorded 87 per cent, the DPH said.
Effective vaccination drives
Effective vaccination drives implemented by the Government of Tamil Nadu might be responsible for the high level of protection against SARS-CoV-2 virus, the department added. In addition, natural infection and subclinical infection due to the weakened circulating Omicron sub lineage of SARS-CoV-2 Virus could have also enhanced the development of antibodies, it said.
In April 2025, a total of 3,643 blood samples were collected from elderly persons as a part of the elderly panel survey conducted in Chennai, Tiruvallur, Tiruvannamalai, Trichy, Dharmapuri and Kanyakumari districts. The preliminary analysis was done on 1,214 samples for SARS-CoV-2 IgG. Even after three years of gap in conducting the Phase - V of the serosurvey, the prevalence of the protective level of SARS-CoV-2 IgG is very high and significant. The phase-V serosurvey has the maximum protective level of Covid-19.