To map the changing trend of the population’s response to SARS-CoV-2 infection, the State began the second round of serological prevalence survey on January 25. The survey is being conducted in all the 30 districts as well as eight zones of Bengaluru.
A serological prevalence survey involves drawing blood samples to detect whether the person was exposed to SARS-CoV-2 in the past and whether he/she has developed Immunoglobulin G (IgG) antibodies to combat the infection.
The first round done from September 3 to September 16 in Karnataka had shown that 16.4% of the 16,585 persons covered under the survey had developed antibodies and 12.7 % had an active infection. The survey, that included people who had COVID-19 infection (prior to the survey) and those who had active infection during the survey, found an overall prevalence of 27.3% in the State then.
V. Ravi, member of the State’s Technical Advisory Committee (TAC), told The Hindu on Wednesday that around 1,100 people from each district are being covered under the second sero-survey. During the first survey, an average of 400 samples from every district was included.
“The plan is to cover nearly 40,000 people from high, moderate and low-risk categories. Sample collection may go on upto two weeks and we should have the results ready by mid-February,” Dr. Ravi said.
The first sero-survey had shown that four districts – Dharwad, Gadag, Chickballapur, Bagalkot, and BBMP’s Mahadevapura zone – were yet to witness a surge then (September). These districts were found to have the lowest estimated prevalence. The overall prevalence was the highest in Ballari with 43.1% while it was the lowest in Dharwad with 8.7%.
“The second round will reveal if there has been a change in the pattern of the disease spread. We can also ascertain whether the districts with low prevalence then have seen the surge subsequently, and if there is a need for further intervention to control the spread,” Dr. Ravi added.
