This suggests that numbers for the ‘low-to-zero’ category may be grossly understated and makes comparison of number of cases in different states meaningless, say epidemiologists. If these states, where asymptomatic cases recorded were very few or zero, had the same proportion of asymptomatic cases as states like Maharashtra or TN, the total number of positive cases in the country could go up by over 6,000, taking the total to well over 21,000.
Then there are states like Delhi, Uttar Pradesh, Rajasthan and Madhya Pradesh, for which there was no data available on symptomatic and asymptomatic cases. If these too have primarily asymptomatic cases, the total number would get pushed even further up.
While the exact number may be a matter of debate, what the data indicates is that comparisons of numbers of cases across states could be misleading. “It’s just not possible that in some states two-thirds to three-fourths of positive cases are asymptomatic, and in some others it’s zero. There’s a serious problem with recording,” said a public health expert.
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States that are following a wider testing protocol could be picking up many more cases and hence their numbers might seem larger relative to the others. This could also help explain the widely varying case fatality rates across states, an issue highlighted by TOI in an earlier report.
“Other states should be having a fair number of asymptomatic cases. It would be a fair conclusion that if they are not being picked up, the testing protocol is probably missing them,” said Prof Rakhal Gaitonde, a public health expert from the Sri Chitra Tirunal Institute for Medical Sciences and Technology in Thiruvananthapuram. “The wider the testing strategy, the higher the chance of picking up milder illness. But the issue also needs to be correlated with the proportion of tests being done per protocol and protocols in use may vary depending on the interpretation of state-level guidelines,” said Dr Gaitonde.
“A state with a good surveillance system will find cases actively. The idea is to detect any circulation going on anywhere so that you take necessary measures to contain it. The real issue is how many cases you found early enough and limit its spread,” said epidemiologist Dr Giridhara Babu of the Public Health Foundation of India, adding that it was possible that when testing kits are limited, some states may employ the available kits stringently in order to confirm diagnosis. “I think there is too much emphasis on the testing as an end in itself. It is the process of active case finding (with or without tests) that defines effective containment,” said Dr Babu emphasizing the need to detect more cases, isolate them and subject their contacts to quarantine.