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Why we need to study asymptomatics and mild COVID19 cases

Such studies will yield better picture of community transmission, yield better insights into peculiarities of the epidemic in India

May 22, 2020 9:43:36 pm
coronavirus test kit, coronavirus latest update, coronavirus today news india, covid-19 latest news india, IIT Ropar, iit news, iit admissions, If we do rigorous surveillance in the country, we would find that individuals with no overt symptoms are in a carrier or quasi carrier state.

By Nerges Mistry

The Indian Council of Medical Research (ICMR) has transitioned from dismissing community transmission into accepting that it could be a reality. A big gap in our knowledge of COVID-19 is the variety of immune responses that it may engender in different individuals and the possibility of the presence of viral carriers.

As reported by researchers from Columbia University, asymptomatic infections were first seen in China and then in Germany and Italy. They were measured to be 55 per cent less contagious than those with symptoms. But, they were shown to be the source of nearly 80 per cent of all infections.

Given their importance in tracking the transmission of COVID-19, the restricted sampling strategy pertaining to those admitted in hospitals with Severe Acute Respiratory Infections (SARI) should be questioned. This is especially because details such as duration of illness of many patients before testing is obscure in many localities. In line with the recommendation of Harvard University’s Ashish Jha, an epidemiology-based random sampling of asymptomatic individuals in parts of COVID19 clusters may yield a better picture of the extent of community transmission. Such sampling might also yield better insights into the immune features of people in the Indian epidemic.

If we do rigorous surveillance in the country, in all likelihood, we would find that individuals with no overt, or extremely mild, symptoms are in a carrier or quasi carrier state. It would be logical to hypothesise that these would be young people, healthy enough to not fall prey to the cytokine storm set off by the virus, but not capable of preventing the spread of the virus. What would be their predominant age group, their health profile and reasons for their innate immunity? Could we not pick up correlates of protective immunity from these individuals which would help in the evaluation of a vaccine – apart from a robust IgG (the antibody that protects against viral and bacterial infections) response.

Moreover, a deep study of viral genomics from viral isolates from such individuals would be salutary. Are these isolates any different from those that infect individuals who have increased severity of symptoms, normalised for age, and health profiles?

The recovering Chinese population in Wuhan, on many of whom such retrospective data would have been recorded, would be an excellent source for the study of the above-mentioned issues. Such studies would give an impetus to the creation of a viral repository. Do our national agencies such as the ICMR and Department of Biotechnology have the foresight to create such a viral repository that is complete with valuable metadata?

Whilst we fight the epidemic with conventional measures, the search for helpful knowledge that illuminates how our species and other protected species react to COVID-19 over a period of time should not be belittled or postponed. The ICMR could have instituted a dedicated cell for basic research to understand the features of the COVID 19 epidemic in India — for example, rapid genomics to understand the virus make-up and its evolution, the significance of antibody responses in COVID infection and the protective co-relate of the human response to COVID-19.

This knowledge will contribute significantly to our survival in the next pandemic when it comes. It’s not a question of “if”.

The writer is with the Foundation for Medical Research, Mumbai

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