Watch out for a highly possible new transmission route of the novel coronavirus – cold chain transportation.
After several months of analysis, Chinese researchers have concluded that imported food via cold chain from high-risk areas overseas may be the origin of the unexpected COVID-19 resurgence in Beijing in June, which started from the city’s largest wholesale market Xinfadi.
Beijing’s new COVID-19 cluster: Inside Xinfadi, biggest wholesale market in Asia.
The study, jointly conducted by several institutions including Beijing Center for Disease Prevention and Control, Chinese Academy of Medical Sciences and Peking Union Medical College and Tsinghua-Peking Center for Life Science, was published in the medical journal National Science Review last week.
The finding is particularly important for countries where community transmissions are contained or suppressed, the authors wrote, warning that the virus could be reintroduced via cold chain transportation of contaminated items and initiate an outbreak.
On June 11, a 52-year-old man was diagnosed with COVID-19 in Beijing, after almost two months without new cases.
Among the 242 environmental samples collected from the places that he had visited, two samples from Xinfadi Market were positive for SARS-CoV-2, leading to an in-depth investigation to the market.
Between June 15 and July 10, a sweeping screening campaign in Beijing found that 169 out of the 368 positive cases has a history of working in Xinfadi.
All seven employees of the booth and five customers who had only visited it in the market were among the earliest confirmed cases.
Researchers examined all salmon in the original sealed package in the cold storage located outside the Xinfadi market, and found that six out of 3,582 samples were positive for the virus.
Genome sequencing of 110 samples from the market showed the virus strains were different from those circulating earlier in China, but similar to those in Europe.
The researchers concluded the COVID-19 resurgence in Beijing was likely to be initiated by an environment-to-human transmission from contaminated imported food via cold-chain logistics.