Are asymptomatic COVID-19 patients safe or silent carriers?

Updated: Jun 3

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.


China said 300 symptom-less carriers of the novel corona virus in Wuhan, the epicenter 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.


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.


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.



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.

WHAT ASIA SAYING ABOUT IT ?

Some countries in Asia include asymptomatic carriers in their total confirmed cases.

In Vietnam, which has just over 300 COVID-19 cases, almost 37 percent 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.

South Korea, which had early success in taming the outbreak through aggressive testing, said 20 percent-30 percent 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.

Singapore, which has the highest number of cases in Southeast Asia, does not give data on asymptomatic cases but has said an overwhelming majority of positive cases in its crowded migrant workers' dormitories show mild or no symptoms.

The Philippines said about 13 percent of its nearly 19,000 cases were asymptomatic. In India, some 28 percent of 40,184 people who tested positive between January 22 and April 30 were asymptomatic, according to a study.


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