MUMBAI: A Serological Survey for SARS-CoV2 infection which was jointly commissioned by NITI-Aayog, the Brihanmumbai Municipal corporation (BMC) and the Tata Institute of Fundamental Research (TIFR), has found 57 percent seroprevalence in slums and 16 per cent in residential societies.
The survey was carried out in the three wards of the BMC. The study also revealed that prevalence in women was marginally higher than men. Agewise, prevalence in populations was comparable in these wards.
The study further revealed a high proportion of all infections is likely to be asymptomatic. "The higher prevalence in slums could be possibly due to population density and shared common facilities (toilets, water points etc.). The infection fatality rate (IFR) is likely to be very low (0.05-0.10%), it would be attributed to effective containment efforts and active measures to isolate symptomatic cases by BMC," said Daksha Shah, BMC health officer.
The study of the survey shows that lesser prevalence in the non-slums areas is due to better social distancing and access to better hygiene in addition to interventions by BMC to stem the spread of infection. These results will be valuable to learn more about herd immunity. Although it is still unclear what level of prevalence leads to herd immunity, findings indicate that at least in slums this could be attained sooner if the immunity exists and persists in a significant proportion of the population," Shah added.
In the first round, 6936 samples (out of the estimated 8870) from general population were collected from three wards (R-North, M-West and F-North) in slum and non-slum areas. Participants were recruited following informed voluntary consent. Anti-SARS-CoV2 IgG antibodies was detected using Chemiluminescence assay (CLIA) by Abbott.