Coronavirus: Chinese expert calls for more investigation into ‘environmental spread’ of Covid-19
- Questions of whether disease can be transmitted via food packaging and other surfaces ‘require us to find patterns and study preventive measures’, Zhong Nanshan says
- But Hong Kong professor says there is little evidence to suggest the virus is spread via cold chain products
Zhong Nanshan, a specialist in respiratory diseases, said at a health conference on Saturday that imported cases and the spread of Covid-19 through the environment were the two major challenges facing China as it sought to contain the problem.
He was referring to the risk of people becoming infected by touching contaminated surfaces, which has been a focus of China’s disease control prevention in recent months though not viewed as the main driver of transmission by many health organisations around the world.
“Can the virus found on cold chain packages infect people? How high does the concentration of the virus need to be to cause infection? How many days can the virus survive [outside the body]? These new questions require us to find patterns and study preventive measures,” Zhong said at the Jinyu Medical Academic Committee Symposium in Guangzhou in southern China.
He also called for greater vigilance among the medical community during the winter flu season as influenza and Covid-19 had similar symptoms.
“We can’t stand for a wrong diagnosis,” he said.
Despite the introduction of strict measures to prevent the spread of the virus, China continues to see isolated outbreaks. On Saturday, 23 new cases were reported, of which 22 were imported.
Recent controls include testing for virus traces on imported frozen products, which Chinese authorities believe may be responsible for the spread of the virus – despite the lack of evidence – and maintaining strict border controls.
Beijing tightened controls around an area of Chaoyang district on Saturday after two new infections were confirmed, both of whom had links to a person who had travelled outside the country but was diagnosed with Covid-19 only after completing the mandatory 14 days’ quarantine. Authorities responded by extending the monitoring period for people returning from overseas by seven days beyond the initial two weeks.
Also on Saturday, the Chinese embassy in the United States announced a further tightening of Covid-19 testing requirements for travellers from America, which has recorded more infections than anywhere else in the world.
Beijing’s latest cases, the first in the capital for 134 days, follow other flare-ups, including in Chengdu, capital of Sichuan province, where about a dozen cases were reported earlier this month.
Health authorities have linked some of the outbreaks to the handling of contaminated packaging of imported seafood products, including a June outbreak at a wet market in Beijing and another in Qingdao in October.
Authorities have suspended food imports from several foreign suppliers whose product packaging tested positive for Covid-19, and implemented prevention measures for workers handling imported frozen food products.
Malik Peiris, a professor at the Hong Kong University School of Public Health, said that while transmission of Covid-19 via contaminated surfaces was possible, there was a lack of evidence to support the idea that the virus could by spread by people handling frozen food packaging.
“The virus can survive for a very long time in cold or frozen temperatures, but whether food packaging contributes to transmission is unclear, and I am not sure of the evidence to support such a contention,” he said.