Are asymptomatic COVID-19 patients safe or silent carriers? Decoded

Reuters | Jun 04, 2020, 04:39 PM IST

China said 300 symptomless carriers of the novel coronavirus in Wuhan, the epicentre of the pandemic, had not been found to be infectious, in a bid to reassure people as countries ease restrictions. But some experts say asymptomatic infections are common, presenting a huge challenge in the control of the disease. Photo: Reuters

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What is Asymptomatic and Pre-symptomatic?

What is Asymptomatic and Pre-symptomatic?

The World Health Organization (WHO) defines asymptomatic cases as those who don`t show symptoms but have been confirmed infected through a lab test. WHO notes there are few reports of truly asymptomatic cases. The incubation period, or the time a person takes to show symptoms after getting infected, is the pre-symptomatic phase, the WHO says. Carriers can infect others during this period. Photo: Reuters

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What health experts' say

What health experts' say

Health experts are not yet sure whether asymptomatic or pre-symptomatic cases are infectious. Some say data so far suggests those cases are probably equally likely to be able to spread infection. The WHO agrees that pre-symptomatic carriers are infectious, and adds that there is also a possibility - although little evidence so far - that people who are asymptomatic may also transmit the virus. The WHO had said in early April that there had been no documented asymptomatic transmissions. Photo: Reuters

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What else does China say?

What else does China say?

China has reported around 83,000 cases of COVID-19, the disease caused by the new coronavirus. It does not include asymptomatic cases in that total official count, but began reporting them separately on a daily basis on March 31. That has raised concerns about Beijing`s commitment to transparency, and some experts say it could also paint a misleading picture of how the virus spreads. Photo: Reuters

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Status in Wuhan that China reports

Status in Wuhan that China reports

Wuhan has tested almost its entire population of 11 million and found no new COVID-19 cases. Wuhan’s low rate of symptomless carriers is in line with China`s previous reporting, said Zhong Nanshan, the government`s senior medical adviser, adding that the result showed that the country didn`t cover up the epidemic as some U.S. politicians claimed. Photo: Reuters

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How about rest of Asia?

How about rest of Asia?

Some countries in Asia include asymptomatic carriers in their total confirmed cases. In Vietnam, which has just over 300 COVID-19 cases, almost 37% were symptomless, according to health ministry data. Researchers concluded that asymptomatic infection was common and found two asymptomatic patients had infected at least four other people. Photo: Reuters

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South Korean lesson

South Korean lesson

South Korea, which had early success in taming the outbreak through aggressive testing, said 20%-30% were asymptomatic. A senior health official said the virus could be widely transmitted during the incubation period, but asymptomatic patients were less likely to transmit it. Photo: Reuters