Responding to concerns that asymptomatic Covid-19 patients were silent carriers, the health ministry as well as the Indian Council of Medical Research (ICMR) said while it was not possible to test everyone, there were adequate provisions under the current testing strategy to test suspected asymptomatic people with contact or travel history, and even those with mild flu-like symptoms in high risk areas. The testing protocol also covers patients with severe acute respiratory illness.
“On the basis of worldwide analysis, 80% of coronavirus patients are asymptomatic or show mild symptoms. Around 15% turn into severe cases and 5% turn into critical cases,” health ministry joint secretary Lav Agarwal said. He added “mild symptoms” to underline that not all non-serious patients were asymptomatic.
Pointing to a varied testing protocol that includes scrutinising low prevalence areas, government said that the possibility of a large number of undetected asymptomatic persons who do not need medical attention is slim.
However, highlighting the limitations of testing, ICMR’s head of epidemiology and communicable diseases, Dr R R Gangakhedkar, said the chances of RT-PCR tests coming positive were higher when there were symptoms and the person was closer to the point of infection.
Dr Gangakhedkar said, as of now, any change in India’s testing strategy did not seem warranted.
In an earlier TV interview, Dr Gangakhedkar had said, “We are equally worried about asymptomatic persons who are around and may be spreading the infection but we must understand that science has not progressed that far where you can detect such asymptomatic cases cost effectively through simpler tests.” He added that one way of addressing it was to ensure that the “index case” helped in tracing his/her contacts or came out for testing and helped through early detection and isolation.
“RT-PCR test usually comes positive when a person is symptomatic. A person takes time to be symptomatic and when asymptomatic people are tested, chances of the test coming positive will remain low as compared to when he is closer to infection. This is the limitation of tests,” Dr Gangakhedkar said. He added that Covid-19 was a new disease and research on its various aspects was still going on simultaneously with interventions.
Dr Gangakhedkar said though such asymptomatic cases were a cause of worry for the government, the challenge was to limit the spread of infection through such people.
Highlighting the impact of lockdown, Dr Gangakhedkar said India had done better than other countries because it used its “strongest weapon very quickly” and as a result, many countries are reporting deaths similar to the number of positive cases in India, which has the world’s second largest population.