2 out of 3 persons in Tamil Nadu developed antibodies against COVID19, finds serosurvey

The latest serosurvey in Tamil Nadu shows 66.2 per cent of the population in the state have developed antibodies against the coronavirus. Are the declining phase of COVID19 second wave and intense vaccination the reasons? Details here.

Gaon Connection
| Updated: July 31st, 2021

The state capital Chennai showed 82 per cent of seropositivity. Photo: By arrangement

In a serological survey conducted this month, it was found that 66.2 per cent of the population in Tamil Nadu has developed antibodies against COVID19.

Of the total 26,610 samples tested, 17,624 individuals had IgG (Immunoglobulin G) antibodies against SARS-CoV-2 virus. In other words, 66.23 per cent of people had developed antibodies against the virus.

The survey report was released by state health minister MA Subramanian in the presence of Principal Health Secretary J Radhakrishnan and Director of Public Health (DPH) and Preventive Medicine TS Selvavinayagam today on July 31.

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The serosurvey was conducted by the Directorate of Public Health and Preventive Medicine in 888 clusters across the southern state. Each cluster consisted of 30 participants drawn ‘randomly’ from a village in a rural area or a street in the case of an urban one.

Positivity rate of serosurvey – I, II, III.

In the earlier serosurveys, the seropositivity was found to be 31 per cent in October/November last year, and 29 per cent (in the second serosurvey conducted in April, this year.

However, the latest serosurvey shows the overall seroprevalence was 66.2 per cent. In other words, 66.2 per cent of people showed positive results for antibodies against the coronavirus. The highest seropositivity was observed in Virudhunagar district at 84 per cent. However, Erode district reported the lowest at 37 per cent.

The state capital Chennai showed 82 per cent of seropositivity.

The health directorate also pointed out that these results could be attributed to various possible reasons such as the timing of serosurvey. It was conducted during the declining phase of the COVID19 second wave in Tamil Nadu.

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Besides, “Intense vaccination drives across the state from January 16, 2021 and inclusion of 18+ age individuals for vaccination would have generated protective antibodies in the population. As on June 10, 2021, 97.6 lakh people got vaccinated (either single or double dose) in Tamil Nadu,” reads the survey report.

It also pointed out that the western districts such Erode, Coimbatore and Tiruppur reported around 45 per cent of seropositivity which could be attributed to the consistent reporting of new COVID19 cases in these regions.

Yesterday, on July 30, Tamil Nadu reported 1,947 fresh COVID19 cases, and 27 people lost their lives to the virus. As per the health ministry data, at least 22.6 million doses have been administered in the state so far.

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