BENGALURU: While the Union Health Ministry recently suggested that state governments conduct do their own sero-surveys in the districts, the chairperson of Karnataka’s Technical Advisory Committee on Covid-19, Dr M K Sudarshan, has suggested that the state should be now looking at doing a rapid sero-survey instead of a random one.Dr Sudarshan said, “There is a need for a rapid sero-survey some time in August and announce the results in September as the Union Government has entrusted it to the states to assess the magnitude of the Covid-19 spread in the districts.”
Karnataka has already conducted two state-level epidemiological surveys. A sero-survey is only to take blood samples. Explaining further, he said, “In the first survey, we have done both RAT and RT-PCR and then the antibody study by taking blood samples. In the second survey, we have done RT-PCR and antibody studies. Now, in the third survey, as detailed exercise is not feasible, it is desirable to do a rapid sero-survey in a sampled population.”
However, the sample criteria will be decided by the TAC members, he explained. He also suggested that for the third survey, children above 10 years of age, who have been already been infected with Covid-19, too should be sampled.
For a random survey, a larger sample will be taken into consideration, a detailed plan needs to be in place and also, it takes a long time for the entire data to be analysed. However, in rapid sero-surveys, there wouldn’t be a requirement of any study design, etc, explains Dr Giridhara R Babu, epidemiologist and member of the Covid-19 TAC.
Citing an example, he says if a sero-survey is done in all district headquarters in the country, then it won’t require any study design, etc. But, if all houses have to be enumerated and only a sample of that is taken, then that is going to take a long time to analyse the data.“Karnataka has already done two rounds of sero-surveys and detailed analysis of the data available. We should also do sentinel sero-survey — using hospitals as the site for surveillance and collecting a regular sample, both in terms of RT-PCR and sero prevalence. In fact, we have recommended this to the Union Health Ministry too,” he said.
According to experts, such sero-survey results will be quicker to find out the infection rate and also how many have antibodies or how far are the community is from achieving herd immunity. “The result of only one of the two sero-surveys has been made public. However, more sero-surveys are necessary to not only identify the districts with lower sero prevalence so that the number of testings can be increased in those districts but also to ramp up the vaccination process. Less sero prevalence can mean that there are groups vulnerable to infection,” explained Dr Manjunath C N, Director, Sri Jayadeva Institute of Cardiovascular Sciences and Research.