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Homeland Security

Asymptomatic transmission of Wuhan virus 'almost certain': expert

ROC Central News Agency

02/10/2020 05:02 PM

Taipei, Feb. 10 (CNA) It is "almost certain" that patients infected with the 2019 novel coronavirus (2019-nCoV) can be infectious even if they do not have symptoms, which might make controlling the virus much harder, a Taiwanese epidemiologist said Monday.

Academia Sinica epidemiologist Ho Mei-shang (何美鄉) said she drew her conclusion from the interaction between the fifth and eighth confirmed coronavirus cases in Taiwan.

The fifth case was a woman who is believed to have been infected with the virus while working in China, came back to Taiwan on Jan. 20, and then apparently spread the disease to her husband, who lives in Taiwan.

What was curious, Ho said, is that the woman did not start showing symptoms until Jan. 25, while the husband started showing symptoms just a day later, on Jan. 26.

If people have to be symptomatic to transmit the disease, that means the incubation period for the husband would have only been one day, very unlikely given the studies on the coronavirus done to date, Ho said.

That means the fifth patient was likely infectious before she became symptomatic, which would make controlling the virus much harder than severe acute respiratory syndrome (SARS), said Ho, who rose to prominence during the fight against SARS in 2003.

SARS patients were only infectious after they showed related symptoms, making it easier to track down a SARS patient's medical history, including when he or she might have been infected with the disease, according to Ho.

On its website, the World Health Organization said current estimates of the incubation period range from one to 12.5 days, with median estimates of five to six days, so a one-day incubation period might not be impossible.

But the issue gained renewed urgency when Taiwan's latest confirmed case, announced on Sunday, was its first asymptomatic patient.

The individual, a man in his 20s, is the younger son of a couple who were diagnosed with the coronavirus Thursday after the family transited through Hong Kong on Feb. 1 following a trip to Italy.

It is believed the man was exposed to the same origin of the virus -- either the plane, the airport in Hong Kong, or somewhere in Italy -- as his family members, the Central Epidemic Command Center (CECC) said, adding that it was still unclear whether he is infectious.

Based on that asymptomatic case, CECC deputy chief Chuang Jen-hsiang (莊人祥) said Monday that the CECC will now screen all people who have lived in the same residence as confirmed patients or who had "high risk close contact" with a confirmed patient, rather than just those who are symptomatic.

Ho said in response that she was all for the government beefing up screening of all people who have had close contact with confirmed cases, regardless of whether they are symptomatic or not, considering that asymptomatic patients could possibly transmit the virus.

She also suggested that health authorities conduct another round of tests on Taiwanese who recently returned to Taiwan on a charter flight from Wuhan, the epicenter of the coronavirus outbreak, on Feb. 3 to make sure they are not infected.

Given that the coronavirus spreads mainly via airborne droplets, Ho reiterated her call for people not to touch their mouths, noses and eyes until after washing their hands to fight the spread of the disease.

She also suggested that an indicator of whether Taiwan's epidemic control measures are working or not will be to see if the number of patients with flu-like symptoms will continue to drop in the coming two weeks.

This is because the preventive measures against the flu and the coronavirus are the same, according to Ho.

(By Chang Ming-hsuan and Joseph Yeh)


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