Barely a couple of days after Pune surpassed Mumbai to become the country's top Corona hotspot, it has emerged that over 50 per cent of Puneites have developed antibodies against the SARS-CoV2 or Covid-19, officials said here on Tuesday.

The findings were revealed in the first sero-survey, 'Epidemiological and Serological Surveillance of Covid-19 in Pune City', funded by the Persistent Foundation.

The survey was conducted jointly by the Indian Institute of Science Education & Research (IISER), Pune, along with the Pune Municipal Corporation (PMC), Savitribai Phule Pune University (SPPU), Translational Health Science & Technology Institute (THSTI), Faridabad, and the Christian Medical College, Vellore.

"The results show 51.5 per cent seroprevalence in 5 Pune Municipal Corporation (PMC) areas. This study was to estimate the proportion of population in high-incidence areas who have been infected and have developed antibodies against Covid-19. The study does not provide information on immunity from subsequent infection," the IISER said.

The 5 worst-hit wards selected for the survey were Yerawada, Lohiyanagar-Kasewadi, Rastapeth-Ravivarpeth, Kasbapeth-Somwarpeth and Navipeth-Parvati with a mixed total population of 3.66 lakh. The principal investigators were Aarti Nagarkar of SPPU and Aurnab Ghose of IISER.

Blood samples from 1,664 consenting individuals were collected from July 20-August 5 and processed to detect the presence of IgG antibodies.

The study indicated that there has been an extensive spread of infection in the 5 wards, with the seroprevalence ranging from 36.1 per cent to 65.4 per cent, and it was substantive across all types of dwellings.

While seropositivity of 56-62 per cent was observed among those living in slums or tenements, it was 43.9 per cent among bungalow residents, and 33 per cent among those staying in buildings. The prevalence is lower among those who have access to independent toilets compared to those who share toilets.

There was little difference among the genders with seroprevalence of 52.8 per cent in men and 50.1 per cent in women while those above age 66 had a lower prevalence of 39.8 per cent.

Among the 5 wards, the percentages were Lohiyanagar-Kasewadi (65.4), Navipeth-Parvati (56.7), Yerawada (56.6), Rastapeth-Ravivarpeth (45.7) and Kasbapeth-Somwarpeth (35.1).

Incidentally, the findings of similar surveys were much lower in Delhi (23 per cent) and Mumbai (36.5 per cent) last month. The PMC plans to start two more sero-surveys with larger sample sizes.

Till Monday, the PMC had recorded 80,407 Covid cases and 2,077 deaths, while Pune district recorded 132,481 cases and 3,247 deaths, higher than Mumbai and Thane.