HYDERABAD: A Covid-19 serosurvey conducted by the Council of Scientific and Industrial Research (CSIR) among 10,427 individuals — its employees at 40 laboratories in two dozen cities and their family members — showed that Hyderabad has the highest prevalence of Coronavirus infections when compared to other cities in the country.
As per the serosurvey findings, the virus positivity rate among 2,073 persons from Hyderabad, whose blood samples were tested for Covid-19 antibodies, was 18 per cent. This is much higher than the average positivity rate among the 10,427 people who took part in the serosurvey — 10.14 per cent. The second highest positivity rate was reported in Chennai (16 per cent), followed by Delhi (14 per cent).The serosurvey report notes that herd immunity “does not seem to be in sight”, and that an effective vaccine may be necessary to control the pandemic.
Results of the first-of-its-kind cohort serosurvey in the country, namely ‘Insights from a Pan India Sero-Epidemiological survey (Phenome-India Cohort) for SARS-CoV2’, have been published on the preprint database Medrxiv. The serosurvey was initiated in June, 2020, at the Institute of Genomics and Integrative Biology (IGIB), and was conducted in other institutes between July and September.
The report also threw up various other important findings. To name one, after being infected with Covid-19, a person might continue to have immunity for up to six months against the same strain of novel-Coronavirus.
The report notes, “While general antibodies to NC antigen are well maintained over three months, neutralising antibodies begin to decline. However, after six months, there is a decline in antibodies to NC antigen, while neutralising antibody levels mostly remain stable after the initial decline. The persistence of antibodies is likely to confer protection against reinfection with the same strain at least for six months.”