Incubation period of Wuhan virus is around 5 days: Study
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|A Transmission Electron Microscopy image of the first isolated case of the coronavirus, as obtained by Reuters on Jan 27, 2020. (Photo: IVDC, China CDC via GISAID/Handout via REUTERS)
While admitting that the estimate is "imprecise," the Chinese team behind a paper published in the New England Journal of Medicine (NEJM) on Wednesday (Jan 29) said their findings support a 14-day medical observation period for people exposed to the pathogen.
The World Health Organization (WHO) said in an update Monday that the incubation period ranged from between two and 10 days before symptoms like fever, cough, shortness of breath and acute respiratory distress emerged.
The incubation period estimate in the new study was based on 10 patients.
The researchers also studied the virus's first 425 patients in order to establish two other fundamental characteristics of the outbreak.
Since it first emerged in Wuhan in December, the number of cases of the 2019 Novel Coronavirus doubled every 7.4 days, the researchers wrote.
They also estimated that each infected person then infected an average of 2.2 other people, a figure known as the basic reproductive number.
The figure doesn't predict how big an epidemic will eventually be, but is a useful measure nonetheless. In this case, it is relatively low: Close to the seasonal flu (around 1.3), much less than the measles (12 or higher) and comparable to the SARS-epidemic of 2002-2003.
The team also found that human-to-human transmission had been occurring among close contacts since the middle of December 2019.
The Chinese findings echo research by a team in the Netherlands that found an incubation period of 5.8 days, with large variations.
And a 27-year-old Vietnamese man who was infected by his father who had travelled to Wuhan showed symptoms in around three days, according to a letter published in NEJM.
In the major Chinese study, half of the 425 cases were patients over the age of 60, and none were under 15 years old.
Foreign governments began flying their citizens out of China's Hubei province, the epicentre of the coronavirus outbreak, as authorities said the death toll there had topped 170.
The health commission for Hubei said on Thursday that deaths in the province from the new coronavirus had risen by 37 to 162, while a further 1,032 cases had been detected.
WHO’s Emergency Committee is set to reconvene behind closed doors in Geneva later on Thursday to decide whether the rapid spread of the virus now constitutes a global emergency.
The United States flew about 200 Americans out of Wuhan, capital of Hubei where most of the cases are concentrated. They were being screened on arrival in California. France, Britain and Canada also have organised evacuations.
The effects of the virus are already weighing heavily on China's economy, the world's second-biggest, with companies cutting corporate travel and tourists cancelling trips.
Various airlines are cutting flights, from British Airways and Lufthansa to Air Canada and American Airlines./.