Mainland China and Hong Kong—two of the world’s COVID-zero holdouts—are drumming up unusual theories and employing increasingly drastic measures to stamp out every single COVID infection, further distancing the regions from other nations that are loosening COVID restrictions based on Omicron’s lower virulence.

On Tuesday, China’s postal service asked the public to receive less mail and started disinfecting international packages to ensure that COVID-19 does not enter China from abroad. The order came one day after Beijing authorities suggested that a new Omicron case in Beijing may have resulted from a letter sent to a 26-year-old woman from Canada. The woman tested positive for the virus on Jan. 14 after receiving the letter from Canada on Jan. 10.

“We do not rule out the possibility that the person was infected through contacting an object from overseas,” Pang Xinghuo, deputy director of the Beijing Center for Disease Prevention and Control, said at a press conference on Monday. On Wednesday, Pang said that if people must receive mail from abroad, they should wear masks and disposable gloves, open packages outdoors, and throw away any external packaging before taking the content of the mail into their homes, according to Chinese media.

On Monday, Canada’s health minister, Jean-Yves Duclos, criticized Beijing’s suggestion that the outbreak may have been sparked through the mail.

“I find this to be, let’s say, an extraordinary view,” Duclos told reporters. “Certainly [it’s] not in accordance with what we have done both internationally and domestically.”

Chinese officials said they had detected traces of COVID-19 on other mail samples sent from Canada and placed postal employees that handled the woman’s letter into quarantine.

Scientists, meanwhile, have almost universally said that it is far more likely that the outbreak resulted from transmission within Beijing, potentially stemming from an Omicron outbreak in the nearby city of Tianjin that has infected dozens of people.  

“The virus may survive transiently on inanimate objects, but the passage from overseas to China would have been way beyond transient,” Leong Hoe Nam, an infectious diseases expert at Singapore’s Mount Elizabeth Novena Hospital, told the AFP.

Dr. Colin Furness, an epidemiologist at the University of Toronto, told Canadian outlet CTV News that Beijing’s explanation is “not credible at all.”

“COVID’s ability to survive on paper depends partly on the roughness of the paper, but it’s unlikely to persist in an active state for more than a day or two,” Furness said.

Putting the blame on the mail, especially from a country like Canada, which maintains chilly relations with Beijing, is a convenient excuse for the government to deflect blame and pin the source of the outbreak elsewhere.

“My sense is that science has nothing to do with it,” says Steve Tsang, a Chinese politics professor at the University of London’s SOAS China Institute. He explained that local Chinese officials are under intense pressure to demonstrate that they have a strong grip in containing local outbreaks in the lead-up to the upcoming Chinese New Year holiday and the Beijing 2022 Winter Olympics, which are set to start on Feb. 4.

Chinese officials want to show “they are leaving no stone unturned” in their adherence to the COVID-zero policy, Tsang says.

Chinese officials have long said they have found traces of COVID-19 on imported goods and have attributed previous outbreaks to imports of frozen chicken wings, fish, and lobsters.

The idea that COVID-19 may live in frozen food containers has at least some merit since the virus may be able to live longer at colder temperatures, but scientists believe that the likelihood is still low that frozen food imports sparked outbreaks in China.

Still, China’s government has doubled down on the idea. Last year, China’s top health officials argued that COVID-19 likely did not originate in China but instead was imported to China from abroad via cold-chain transmission. After a joint investigation between the World Health Organization and Chinese authorities concluded early last year, Chinese officials played up the idea that COVID-19 was imported into China from abroad and said it was time to start engaging in origin tracing efforts elsewhere.

Meanwhile, in Hong Kong, a Chinese special administrative region that is pursuing a similar COVID-zero strategy, officials traced a case of COVID-19 on Wednesday to a pet shop, claiming that an imported hamster from the Netherlands may have infected someone with the virus. Due to the COVID case, Hong Kong officials announced they would slaughter over 2,000 pets including hamsters and rabbits while banning all future rodent imports into the city.

It’s not certain whether a hamster infected the patient, but as a precautionary measure, authorities say, they are rounding up thousands of hamsters and other small mammals that city residents have purchased in the last few weeks for “humane disposal.”

“The risks of these batches [of hamsters] are relatively high and therefore [we] made the decision based on public health needs,” Dr. Leung Siu-fai, Hong Kong’s director of Agriculture, Fisheries and Conservation, said Tuesday.