Pet hamsters can pass on Covid-19 to humans and were the most likely source of an outbreak of the Delta variant in Hong Kong, a study has revealed.
While human-to-animal coronavirus transmission has previously been reported, there had been no evidence, with the exception of farmed mink, that infected animals could pass the virus on to humans – until now.
Researchers at the University of Hong Kong (HKU) found a pet shop in the Causeway Bay area of the city was the likely source of a Covid outbreak which saw more than 2,000 hamsters culled after a staff member and customer contracted the Delta variant of the disease earlier this year.
A 23-year-old female worker at the pet shop, who had received two doses of the Pfizer-BioNTech vaccine, tested positive for Covid on 15 January, becoming Hong Kong’s first Delta case in more than three months.
A mother who visited the shop with her daughter also tested positive on 17 January, while her daughter, son and husband were all subsequently confirmed to have the disease.
According to the study, published in The Lancet medical journal on Saturday, eight (50 per cent) of the 16 tested Syrian hamsters in the pet shop and seven (58 per cent) of the 12 Syrian hamsters in the warehouse supplying it were positive for Covid.
Genome sequencing suggested the hamsters had been infected with the Delta variant around mid-October.
The source of infection of the warehouse remains to be definitively ascertained, however the researchers said their findings suggested the virus had been transmitting within this group of hamsters for some weeks, either at the warehouse or at a hamster farm supplying the warehouse.
“Since Delta viruses had not been in circulation in Hong Kong for three months, importation of infected hamsters was therefore the most likely source of introduction of this chain of infection into Hong Kong,” the experts concluded.
Professor Leo Poon, a lead researcher, said the study provided “convincing evidence” of pet hamsters naturally acquiring the Delta coronavirus variant and being the source of human infection.
“We also provide evidence suggesting the possibility of international movement of SARS-CoV-2 infection via the pet trade,” he said.
He added: “Both genetic and epidemiological results strongly suggest that there were two independent hamster-to-human transmission and that such events can lead to onward human transmission.
“Importation of infected hamsters was the most likely source of virus infection.”
