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India should focus on symptomatic patients, say experts

Suggestion comes after WHO has said asymptomatic patients are responsible for only a small percentage of infection spread

India ought to be focussing on symptomatic patients, epidemiologists and public health experts told The Hindu a day after an official at the World Health Organisation (WHO) said asymptomatic patients are responsible for only a small percentage of the infections spread.

Maria Van Kerkhove, Head, WHO emerging diseases and zoonosis unit, said at a press briefing on Monday night: “It still appears to be rare that an asymptomatic individual transmits onwards. What we really want to be focussed on is following the symptomatic cases. If we followed all of them, traced their contacts and isolated them we would drastically reduce transmission.”

Intense debate

The role played by asymptomatics — those who carry the virus but never show symptoms — has been a matter of intense debate since March when the pandemic established its global spread. Policy decisions such as the wearing of masks, stringent lockdowns, restricting movement and now, restarting economic activity, are in part guided by the role of asymptomatics in spreading infections.

The WHO’s statement drew opprobrium.

Also read: Focus on the curve

A statement by the Harvard Global Health Institute on Tuesday accused the WHO of “creating confusion” by reporting that asymptomatic patients rarely spread the disease. “All of the best evidence suggests that people without symptoms can and do readily spread SARS-CoV2, the virus that causes COVID-19.” In their estimate, about 20% of people infected with COVID-19 never develop symptoms and they cited modelling studies to show that 40-60% of spread is from people before they had any symptoms.

Stringent criteria

In March, India began by testing only those who showed symptoms — cough, difficulty breathing and respiratory infection — and had a travel history. It expanded the criteria to gauge the extent of community spread but now several States have reverted to a more stringent testing criteria.

Also read: Curves and recoveries: On India’s coronavirus numbers

The Health Ministry maintained that 69 out of 100 COVID-19 patients are “asymptomatic” in India. However this also includes those who show mild disease and could include another category called presymptomatics. The latter are those who eventually show symptoms but asymptomatics are those who never manifest symptoms at all. Importantly, both categories are capable of being infectious and the debate is about the degree to which both categories do so.

Also read: Novel coronavirus can be transmitted even before symptoms show up

“It’s true asymptomatics don’t spread much and that it is the symptomatics who are the drivers of clusters,” Dr. Giridhar Babu, physician and epidemiologist, told The Hindu, “that said, WHO should be commissioning studies to understand spread within the distinct categories of asymptomatics and presymptomatics. Decisions such as these have public health implications in terms of who should be availing tests.”

“For India, the asymptomatics can range from as low as 28% to as high as 68%. What we’d found was that the contact tracing data of nearly 40% of patients couldn’t be traced,” Manoj Murhekar, Director, ICMR-National Institute of Epidemiology, told The Hindu.

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Printable version | Jul 7, 2020 7:45:40 PM | https://www.thehindu.com/news/national/india-should-focus-on-symptomatic-patients-say-experts/article31789783.ece

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