The SARS-COV-2 causing the coronavirus case load in Telangana and also across the country for the past two months, markedly from December onwards, could be because of the proportion of population with discernible antibodies to it, observe public health experts.
“Yes, it is true. Hospital beds are not under stress anywhere in the country, despite elections in Bihar, and Telangana and major festivals of all communities. While it is difficult to pinpoint a single reason, a number of reasons may have contributed,” says Public Health Foundation of India’s Indian Institute of Public Health (IIPH) - Hyderabad director Dr. G.V.S. Murthy.
Recently published data in Lancet showed 54.1% of sampled population from Mumbai slums against 16.1% of sampled population from non-slum habitations were positive for past infection with coronavirus. Another study from Karnataka conducted in July/August found that the proportion of urban populations exposed to SARS-CoV-2 in the recent past was 53.8% and in rural areas it was 44.1%.
“This is very different from the low prevalence of 0.73% across 21 States in May/June. So, it is likely a significant proportion of the population was infected by September, with most suffering minor infections. The virus needs a susceptible population to spread and if one out of every two people in the community have already been infected earlier, the transmission potential gets reduced,” he explains.
The Mumbai study has other implications too. In overcrowded, poorly ventilated populations, the infection would have spread very rapidly in the initial 3-4 months while in less densely populated, higher socio-economic strata adherence to personal protection measures like masking, physical distancing and sanitisation, may have played a role, says Dr. Murthy
Caseload reduction also means it is likely that the ‘herd immunity’ required to halt transmission with SARS-CoV-2 may be between 50-60% or even lower, which seems to have already been achieved in the lower socio-economic strata.
However, “it is absolutely essential governments invest resources to conduct sero-prevalence studies on a sample population at periodic intervals to help in tracking the spread and control of the infection better,” insists the director.
Dr. Murthy is of the opinion that Telangana’s COVID caseload reached a peak earlier than seen across the country.
The number of new cases peaked between August 26-30 when the average daily new cases were 2,880. This dropped to an average daily new case load of 1,600 by November 2 and further to 413 from December 24-29. “This is a drop of 86% compared to the peak in August and this is an even more significant reduction than seen in the national figures. This seems a valid trend,” he maintains.
“It is also quite possible to under-report cases either through not releasing data or by low testing, but it is next to impossible to hide a large number of deaths. So, the falling death count, which has been less than five per day in Telangana since November 19, is a reliable indicator that the severity of COVID has reduced due to early recognition and prompt initiation of appropriate treatment,” he says.
Across the country, from more than 90,000 new cases every day in September second week, cases dropped to less than 50,000 new cases per day consistently in the last week of October to less than 25,000 from December 20. This is a huge drop of more than 75% from the peak. Such a consistent decline despite winter and festivals augurs well, adds Dr. Murthy.