KUALA LUMPUR, Feb 11 — The incubation period for the novel coronavirus from China ranges up to 24 days, 10 days longer than experts previously thought, according to new research on the health crisis.
This means that those infected with so-called 2019-nCoV could manifest symptoms of the deadly sickness much later on after contracting its transmission source. The current incubation period is 14 days long.
However, the research, co-authored by Dr Zhong Nanshan, who discovered the Severe Acute Respiratory Syndrome (SARS) coronavirus in 2003, found that the median incubation period was only three days for the 1,099 patients that were surveyed from 522 hospitals.
It also noted that its surveyants had a relatively lower fatality rate than the SARS and Middle East Respiratory Syndrome (MERS) coronaviruses, and the median incubation period was shorter than a recent report of 425 patients, which was 5.2 days.
“Our findings have provided evidence from a much larger sample size to guide the duration of quarantine for close contacts,” the researchers said in the study titled “Clinical characteristics of 2019 novel coronavirus infection in China“ that was published on Sunday. It has not been peer-reviewed.
A total of 71.8 per cent of those surveyed, meanwhile, were in contact with people from Wuhan, the epicentre of the outbreak that has killed 1,018, all but two of those in mainland China.
A total of 43.95 per cent of patients were local residents of Wuhan. About one-third of them had visited Wuhan, and only 1.18 per cent had a history of contact with wildlife.
The median age was 47, with only 0.9 per cent of patients aged below 15 years.
Fever (87.9 per cent) and cough (67.7 per cent) were the most common symptoms of those surveyed, on the other hand, whereas diarrhoea (3.7 per cent) and vomiting (5.0 per cent) were rare. A total of 25.2 per cent of patients, meanwhile, had at least one underlying disorder such as hypertension or chronic obstructive pulmonary disease.
Fever occurred in only 43.8 per cent of patients with 2019-nCoV on presentation, but developed in 87.9 per cent following hospitalisation. Severe pneumonia occurred in 15.7 per cent of cases.
“Absence of fever in 2019-nCoV ARD is more frequent than in SARS-CoV (1 per cent) and MERS-CoV infection (2 per cent) and such patients may be missed if the surveillance case definition focused heavily on fever detection,” the researchers said, using the ARD acronym for acute respiratory disease due to the Wuhan-linked coronavirus.
The study also found that the routes of transmission might have contributed considerably to the rapid spread of 2019-nCoV, noting that stool specimens and rectal swabs did test positive for the coronavirus, though this was a small figure.
“Collectively, fomite transmission might have played a role in the rapid transmission of 2019-nCoV, and hence hygiene protection should take into account the transmission via gastrointestinal secretions,” the researchers said.
Malaysia has seen 18 confirmed cases, of whom 12 are Chinese nationals. After receiving treatment in isolation wards at medical facilities, three of the patients tested negative for the virus and were allowed to return home — but two of them are still in the country, according to the Chinese embassy.