An estimated 1.7% of the population surveyed in the State had both IgG antibodies and active infection at the same time.
Giridhar R. Babu, member, State’s Technical Advisory Committee (TAC), who designed the survey protocol, told The Hindu that there are some individuals who show the presence of virus and IgG antibodies at the same time. “While the overall adjusted prevalence of COVID-19 in the State is 27.3% (combined IgG and active infection), the total number of those who have developed antibodies and those who currently have the infection is 29.1% (16.4% plus 12.7%). The difference 1.7% is the estimated percentage that have the active infection and IgG antibodies at the same time,” Dr. Babu said.“This is because some of the RNA remnants can remain in the body and such individuals can test positive for as long as four weeks. In the case of infection in the recent past, IgG will be there. In addition, they can test positive by RTPCR also,” he explained.
Stating that such a finding had not been found in any sero surveys done in other states, Dr. Babu said: “Surveys in other states only looked at presence of IgG antibodies. Ours is first to do both IgG and active infection through RAT/RT PCR at the same time.”.