The Municipal Corporation of Greater Mumbai has conducted its fifth serological survey in the city in the wake of the COVID-19 pandemic. The sero survey found that 86.64 percent of the city’s residents had COVID-19 antibodies.
A sero survey is undertaken to find data on the proportion of infected and asymptomatic people, especially during a global pandemic like COVID-19. A sero survey has multiple uses and can ascertain the likely impact and spread of the infection based on its findings. It can pinpoint high-risk categories, herd immunity or infection and other behaviour in specific groups such as the vulnerable and the asymptomatic.
A sero survey can help develop customised care, cure and precautions for all such groups. It can also determine the duration of immunity of those who took vaccines or did not; and even those who recovered from the virus or got infected again.
This sero survey was conducted by the municipal authority in preparation for the expected third wave of COVID-19. The survey was undertaken by Public Health Department and LTMMC & GH, Sion Hospital with the support from A.T.E. Chandra Foundation and IDFC Institute. A total of 8,674 samples were collected from individuals of age 18 and above from the 24 wards of the city of Greater Mumbai. The antibodies were tested using the ELISA assay.
The overall seroprevalence in the city was at 86.64 percent, with 87.02 percent prevalence in slum areas and 86.22 percent prevalence in the other wards of the city. Perhaps surprisingly, women had a higher seroprevalence than men at 88.29 percent compared to 85.07 percent.
Out of the total participants, around 65 percent had received at least one vaccine while 35 percent were yet to be vaccinated. Among the vaccinated, both partially and fully, overall seropositivity was at 90.26 percent.
Seropositivity in the unvaccinated population was lower but still significantly high at 79.86 percent. Finally, the survey found that healthcare workers had seropositivity of around 87 percent.
While the survey found that 86 percent of the city’s population was exposed to the virus, preventive measures are still recommended since the survey did not measure the level of antibodies in individuals.
(Edited by : Shoma Bhattacharjee)