First Signs Of Herd Immunity? Mumbai Serosurvey Detects 57 Per Cent Sero-Prevalence In Slum Areas

A serological survey for Covid-19 infections which was conducted in three wards of slum and non-slum area of Mumbai has found on an average 57 per cent Sero-prevalence in slums and 16 per cent sero-prevalence in non-slum areas.

The survey involved collecting 6,936 random samples in the first half of July to determine the estimated sero-prevalence among the populace. Sero-prevalence means determining the level of a pathogen (in this case SARS-CoV-2) in a particular population sample.

The survey has determined a 57 per cent sero-prevalence in slums which has led many to question whether the impacted areas have already attained herd immunity.

The surveyors conclude that asymptomatic cases are likely to be a higher proportion of all infections - with the slum areas having a higher infection rate due to population density. More importantly if one considers the serosurvey results, the infection fatality rate (IFR) is likely to be very low in the range of 0.05 per cent to 0.10 per cent.