A serological survey conducted in five sub-wards in Pune has revealed that 51.5% of those surveyed have antibodies for the coronavirus. These sub-wards have seen the highest incidences of coronavirus cases, the Indian Institute of Science Education and Research said on Monday.

The sero-survey was jointly conducted by the Pune Municipal Corporation, Pune University, Indian Institute of Science Education and Research, Translational Health Science and Technology Institute, Faridabad, and Christian Medical College, Vellore, the press release said.

The samples for the study were collected between July 5 and August 20, the statement said. The Pune Municipal Corporation’s sub-wards were divided into three categories – high incidence (of Covid-19), medium incidence and low incidence, based on data of cases till June 1. From the high-incidence sub-wards, five were chosen – Yerwada, Lohiyanagar-Kasewadi, Rastapeth-Ravivarpeth, Kasbapeth - Somwarpeth, and Navipeth-Parvati.

As many as 1,664 persons were recruited for the survey from the five sub-wards. “The study included all types of dwellings; hutments, tenements, apartments, bungalows falling within the selected grid,” the press release said. One adult individual was chosen from every fifth house, taking care to maintain a gender balance. The study including adults who reported no known acute illness.

The study found prevalence of antibodies in 51.5% of persons surveyed. The lowest rate – 36.1% – was in Kasbapeth-Somwarpeth, while the highest – 65.4% – was in Lohiyanagar-Kasewadi, the press release said. “This indicates that there has been extensive spread of infection in these prabhags [sub-wards],” it added.

There was very little difference in seropositivity between men and women – 52.8% for men and 50.1% for women. Individuals above 65 years of age had a lower seropositivity rate than the younger population. The seropositivity rate was highest where people lived in hutments (62%) or tenements (56.2%) than in apartments (33.2%) and bungalows (43.9%). The prevalence was also highest in dwellings smaller than 150 square feet. Usage of common toilets also increased antibody prevalence rate, the press release.

The statement said that the survey showed past infection, but it cannot be taken as an indication of resistance to future infection. “Neither is the high seroprevalence necessarily an indicator of population-level immune protection,” it said.

Last month, sero-surveys conducted in Delhi had shown that 23% of the residents may have been infected. A similar survey carried out in Kolkata showed the prevalence of antibodies at 14%. In Mumbai, the results were 57% in slums and 16% in residential complexes.

India reported 57,981 cases in 24 hours on Monday, taking the total count to 26,47,663. There are now 6,76,900 active cases, while as many as 19,19,842 people have recovered. The number of deaths in India crossed the 50,000-mark after 941 people died in 24 hours. The toll is now 50,921.

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