It is extremely unlikely for Covid-19 to spread via contaminated post, Canada’s health authorities said, after their Chinese counterparts suggested this may be the source of an Omicron case found in Beijing over the weekend. The Beijing Centre for Disease Control and Prevention on Monday said traces of the Omicron variant had been found on a letter mailed from Toronto and received by the person, and suggested that the letter could have been the source of the infection. On Tuesday, the Beijing CDC said a close contact of that person had also tested positive – the second local case of the highly infectious Omicron strain in the capital . But Health Canada, in a written reply to the South China Morning Post , said while mail could be contaminated, “the risk of Covid-19 infection when handling paper mail or cardboard packages, including international mail, is extremely low”. “In general, coronaviruses including variants do not spread from products or packaging shipped over a period of days or weeks,” the health agency said. It came after Canadian Health Minister Jean-Yves Duclos on Monday sidestepped a question about the claim, saying he had to consult the experts, though he described it as “extraordinary”. Chinese authorities have repeatedly said the coronavirus has been found on imports , usually frozen goods, but scientists and health authorities elsewhere have rejected this as a route of transmission, saying the virus does not survive long enough on surfaces. Emanuel Goldman, a professor of microbiology at Rutgers University in the US, said it was impossible for a letter sent from Toronto on January 7 to infect a person in Beijing four days later. “No chance,” Goldman said. “Many researchers have looked hard and repeatedly at surfaces like paper, and live virus is simply not found after more than an hour or two, especially when the amount of virus used at the outset is in a real-world amount.” He said there was no need to be concerned about samples from the letter testing positive. “It’s possible that viral RNA may be found, but that’s like finding the corpse of the virus, so there is no cause for alarm,” he said. The Beijing CDC said traces of the virus had also been found on five other items of mail out of 54 that had been sent from the same area in Toronto. But the health authorities did not say if they were able to culture live virus from those samples. Goldman said the theory that Covid-19 could spread via international packages or cold chains had long been dismissed by scientists based on published data. “Even in hospitals treating Covid-19 patients, live virus on surfaces is not found,” he said. “This is a fragile virus that you contract by breathing, not by touching.” Nevertheless, Beijing continues to suggest that cold chain and imported goods could have brought Covid-19 to China – including to Wuhan, where the virus was first reported. It has also made policies based on that theory, particularly as Beijing prepares to host the Winter Olympics from February 4. China Post on Sunday ordered that all mail from overseas be disinfected and anyone handling it must have vaccine booster shots. International post is to be handled separately from domestic mail, and companies that handle courier deliveries and mail from overseas have been asked to reduce services from high-risk countries. It said measures were being taken to reduce risks and improve safety ahead of the Games and an expected increase in international post ahead of the Lunar New Year on February 1. University students have also been affected by the Beijing CDC’s latest claim. Tsinghua University in Beijing has suspended a service that allows students to borrow books from institutions outside mainland China – including Hong Kong and Macau – via the China Academic Library and Information System. It said the decision was based on the allegation about the origin of the first Omicron case in Beijing.