Telangana: 1 in 4 in State found to have antibodies
- The occurrence of infection among different populations;
- How many people have mild or asymptomatic infection, and who may not have been identified by routine disease surveillance;
- The proportion of fatal infections among those infected;
- The proportion of population who may be protected against infection in the future
Koti: One in every four persons in Telangana has antibodies against Covid-19 virus, the Indian Council of Medical Research's sero-survey in the State has revealed. The third round of sero-surveillance, led by the National Institute of Nutrition (NIN) conducted in three districts of Telangana in December 2020 as part of the national sero-survey by the Indian Council of Medical Research (ICMR), has put the sero-positivity rate (IgG positivity indicative of silent, prior exposure to SARS-CoV2) at 24 per cent. The sero-survey was conducted in Jangaon, Nalgonda and Kamareddy districts.
Sero positivity implies that the person has developed antibodies against the virus. It means that the person was infected at some point and developed immunity against it.
The ICMR strategy has been to do repeat cross-sectional sero-studies in the same geographic locations so that the infection transmission trends could be documented and studied, ICMR-NIN said on Tuesday. The first round of the sero-survey, conducted in May 2020 in the same districts showed a sero prevalence of 0.33 per cent while the second round in August showed 12.5 per cent prevalence and the latest round showed 24.1 per cent prevalence.
The sero-prevalence at the national level went up 3.1 times between August and December but in Telangana, this went up by two times. Telangana's sero-prevalence (24.1 per cent) as of December 2020 was similar to that of the national average (24 per cent). "This shows the effectiveness of robust containment measures in the state including quarantine, contract tracing and testing strategies," said Dr R. Hemalatha, Director of ICMR-NIN.
ICMR nodal officer Dr Laxmaiah said that good compliance and cooperation shown by the public in adopting universal mask wearing and other Covid-19 protocols before the survey ensured that infection transmission remained slow and steady in the state. Since three-fourths of rural population is still susceptible, all non-pharmacological Covid-19 measures like wearing masks, hand sanitisation, physical distancing should be continued, he said.
WHY SERO SURVEILLANCE?
Serologic tests measure the antibody response in an individual. Antibodies to COVID-19 are produced over days to weeks after infection with the virus. The presence of antibodies indicates that a person was infected with the COVID-19 virus, irrespective of whether the individual had severe or mild disease, or even asymptomatic infection. Surveillance of antibody seropositivity in a population can allow inferences to be made about the extent of infection and about the cumulative incidence of infection in the population. The use of serology in epidemiology and public health research enables understanding of: