The overall Covid-19 seroprevalence in Mumbai stood at 86.64%, showed the results of the fifth sero survey announced by the city’s municipal corporation on Friday, The Hindu reported.

A sero survey tests a sample population in a region to assess whether they have antibodies against a particular infection. The presence of antibodies indicates they may have been exposed to the infection even if they hadn’t developed symptoms of the disease.

A higher seroprevalence number in a state suggests infection spread rapidly among the population, while a lower number indicates a limited spread either because the state was able to limit the spread of the virus through effective pandemic-control measures, or the virus is yet to make an inroad in some pockets.

The fifth sero survey in Mumbai covered 8,674 people and was conducted between August 12 and September 9, the Brihanmumbai Municipal Corporation said on Friday. The civic body added that participants from all 24 wards of the city were selected by random sampling as well as from among the residents who were visiting municipal dispensaries and medical clinics in slum and non-slum areas.

The Brihanmumbai Municipal Corporation said that Covid-19 antibodies were found in 90.26% of residents who were fully or partially vaccinated and in 79.86% of unvaccinated citizens.

Around 65% of the participants of the study had received coronavirus vaccines, either partially or fully, and 35% were unvaccinated, reported News18.

The civic body has warned that seroprevalence results do not necessarily indicate high protection levels from the infection, reported NDTV. The study emphasised on using face masks and hand sanitisers as well as maintaining physical distance.

Other key findings

The results of the sero survey showed that antibodies were found in 88.29% of women who participated in the survey. This is marginally higher than 85.07% seroprevalence among males.

There was also a marginal difference between seroprevalence in slum and non-slum areas. While the results showed around 87.02 % residents of slums had antibodies, the figure was 86.22% in the non-slum population.

Seroprevalence was 87.14% among health workers, who formed 20% of the sample size.

The first and second sero surveys were conducted in July and August last year in three wards. The third survey was undertaken in March this year in 24 wards. The fourth one was done between May and June among the paediatric population. The results of the last survey had shown that 51% of the children in the city had antibodies.