(Bloomberg) -- China is pointing blame for a recent locally transmitted case of the omicron variant in Beijing at overseas mail.

Residents in the Chinese capital are being urged to wear masks and gloves when opening mail from abroad and to limit international purchases as authorities try to figure out how Covid-19 seeped through tight borders ahead of the Winter Olympics that start next month. 

The city reported one local infection from the variant. The person hadn’t left Beijing two weeks before testing positive but occasionally handled international mail at work, the Beijing Municipal Health Commission said on Monday, adding that no other people who lived and worked with the patient tested positive.

Over the past year, Chinese officials and state-backed media have alleged Covid-19 was coming into the country -- and may have even originated -- from frozen food from abroad. Global health authorities have downplayed the likelihood of such transmission, with the World Health Organization and the U.S. Centers for Disease Control and Prevention saying the chance of getting Covid from frozen foods is very low. In November, China warned the virus could be transmitted to other parcels, testing hundreds of packages of children’s clothing after three workers at an apparel factory tested positive.

In the latest instance, samples taken from the package and some documents inside the mail -- sent from Canada on Jan. 7 and arriving in Beijing via the U.S. and Hong Kong, before being received by the person on Jan. 11 -- tested positive for the virus. Genetic sequencing shows the variant detected in the patient is different from omicron-infected patients elsewhere in China but bears “high similarity” to infected travelers from North America and Singapore in December, according to the municipal health commission.

Beijing health authorities said the findings mean they cannot rule out the possibility of the person getting infected through overseas mail.

Authorities urged residents to minimize purchases from abroad where Covid-19 is rife and maintain a safe distance with couriers when taking deliveries as it warns of heightened transmission risks during the winter.

Shenzhen also said on Monday that a person handling frozen reagents imported from overseas developed a sore throat and tested positive after coming into contact with parcels from North America without proper protection.

Concern that overseas mail may be contaminated also spurred China’s State Post Bureau to mandate thorough disinfection of exterior packaging and booster shots for mail-handling staff and couriers.



(Adds Post Bureau disinfection requirement in last paragraph.)

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