COVID-19: We need not be in chains, but we should not shed our armour, says PHFI’s Dr K Srinath Reddy

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April 21, 2020 4:30 AM

It is difficult to comment on a trend—the only thing that can be said with some degree of certainty is that asymptomatics are largely below 50-45 years of age.

 

Dr K Srinath ReddyDr K Srinath Reddy

A top scientist at the Indian Council of Medical Research (ICMR) has said that nearly 80% of the SARS CoV-2 infected in the country could be asymptomatic, and this a major concern for the country. So, even as we move on a phased exit from the lockdown, the COVID-19 challenge for India could just get tougher. In a conversation with FE’s Sarthak Ray, the president of the Public Health Foundation of India, Dr K Srinath Reddy, who is also a member of the executive group of the International Steering Committee of WHO’s COVID-19 SOLIDARITY trial, talked about the issue of detection of asymptomatic cases, what India needs to do protect its vulnerable, and how social distancing will need to be in force for a year if we are to meaningfully combat COVID-19. Edited excerpts:

What are asymptomatic COVID-19 cases? How are they different from pre-symptomatic cases?

Asymptomatic cases are those that are testing positive for COVID-19 without them having shown any of the symptoms that are typical of the disease. Some of these cases may be pre-symptomatic, i.e. they could have undergone testing at a time in infection when they are not showing symptoms, but may show symptoms later. In other cases, i.e. if these are not false positives, there is a chance that these individuals have been exposed to SARS CoV-2, but their immune system managed to beat the infection.

Are asymptomatic cases being reported widely? Is there any trend emerging around these cases?

It is very difficult to catch asymptomatics unless individuals get themselves tested on demand, or public health authorities organise testing in a cluster. The Delhi chief minister recently talked about asymptomatic cases, Boston 25 (a digital video news outlet) has reported that, of 397 people in a homeless shelter in Boston, 146 tested positive and all of them exhibited no symptoms. In Santa Clara, California, 3,300 people volunteered for antibody testing for COVID-19—extrapolating from the test results using various models, CNBC reports, the study found that anywhere between 2.5% and 4.2% in Santa Clara could have antibodies to the virus, indicating they had been exposed to the virus but perhaps either remained asymptomatic or developed very mild symptoms that they didn’t suspect COVID-19.

It is difficult to comment on a trend—the only thing that can be said with some degree of certainty is that asymptomatics are largely below 50-45 years of age.

In both the Santa Clara and Boston cases, testing led to identifying asymptomatics. Is that what the government should be looking at—wider testing?

See, as both examples should tell you, this works for individuals volunteering to test despite not having symptoms, or on testing being undertaken for a cluster. So, if there is on-demand testing, or if the government identifies a cluster for testing and rolls this out, you will catch some asymptomatic cases. A population-wide testing, or even large-scale testing, is neither advisable nor feasible. You will have to consider the logistical and resource demand this places—on the requirement for testing kits, reagents, lab personnel, protective gear, sample collection paraphernalia, etc—and ask does India have the capacity for this and can it realistically develop such capacity or arrange for the requirement to be met? More so, given you need continued testing to see if the person is truly cured.

The other factor to consider is how frequently you will be testing the same set of people. After all, testing true negative today is not a guarantee that a person wouldn’t get infected tomorrow.
Indeed, that brings us to the nature of testing and the results themselves. No testing mechanism is 100% failsafe. So, imagine a scenario in which a person tests false positive and is assumed to be asymptomatic—he is then quarantined (though to zero effect since he didn’t have the infection in the first place) and then tests negative after the quarantine in both the first and the confirmatory test (again, because he never had the infection in the first place). This would make him confident that he has somehow developed adequate immunity, and he would drop his guard, unaware that he never had the infection and could still contract it. While we don’t know that true asymptomatics could be viral shedders or not—i.e. whether they could still end up infecting other people—we also don’t know if they aren’t. This means if they are going to walk about having tested false negative, there are chances they will be spreading it to other people. So, testing is without doubt very useful, but at the population level or even at a large scale, it simply may not be the answer.

So, what should be our strategy assuming there are a significant number of asymptomatics in the population?

Let testing continue as it is at present, with the ICMR reviewing and updating the strategy as and when necessary. Apart from that, there is a need to continue with social distancing practices for whatever duration deemed necessary. People will also need to adopt the advised hygiene practices to keep the virus at bay. Most important, however, will be to protect our elderly and other high-vulnerability groups, such as those with comorbidities like diabetes, COPD, hypertension and coronary diseases—for this, perhaps, we need to have some household and individual risk-profiling from data on underlying diseases. It will also be necessary to protect rural areas from transmission from urban areas; to that end, while ensuring supply of essentials in villages, the government has to minimise transport linkages (other than those for emergency purposes) between urban areas, where COVID-19 in India is at present concentrated, and rural areas that are unexposed to the virus from foreign travellers or their contacts.

What is the outlook on how long social distancing has to be practised in India?

We have to be ready for some forms of social distancing for another year, since we do not know yet if the virus will flare up in winter. Until we are sure that it is quiescent or curbed through a vaccine or herd immunity, we cannot let down our guard. We need not be in chains, but we should not shed our armour.

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