A state serosurvey shows nearly all elderly in Tamil Nadu aged 60 and above carry COVID-19 antibodies with preliminary analysis. The results suggest nearly universal immunity in this high-risk group.
Tamil Nadu’s fifth COVID-19 serosurvey focused on senior citizens across six districts and produced striking results. Officials collected over 25,000 samples by phase, drawing 1,214 from people aged 60 and above for preliminary analysis. The results suggest nearly universal immunity in this high-risk group.
According to The Economic Times, Health Minister Ma Subramaniam announced that 97 per cent of seniors tested in April 2025 had protective antibodies. The survey built on earlier phases: 32 per cent immunity in October 2020, dipping to 29 per cent in April 2021, then rising to 70 per cent in August 2021 and 87 per cent by December that year.
Director of Public Health T S Selvavinayagam explained that antibodies in the blood show past exposure to the virus or vaccine. He credited two forces: a vaccination drive that reached over 95 per cent of the population with at least one dose, and natural infections driven by milder variants like Omicron sub-lineages. Together, these created “hybrid immunity” in many individuals.
Selvavinayagam noted that high seroprevalence is linked to lower rates of severe illness and death among those infected. He said doctors and health workers in Tiruvallur, Tiruvannamalai, Trichy, Dharmapuri, Kanyakumari and Chennai now see COVID-19 as less of a threat for seniors, thanks to their immune coverage.
The survey method used population-proportionate sampling to ensure district-level accuracy. Each lab followed uniform collection and testing procedures to maintain consistency. Officials believe the data can guide future public health planning, especially for booster policies and resource allocation in clinics and community centers.
Looking ahead, the health department plans to monitor immunity in other age groups and adjust vaccination campaigns based on emerging variants. For now, the survey offers reassurance: Tamil Nadu’s seniors carry the antibodies needed to keep COVID-19’s worst effects at bay.
