COVID-19: What Hamsters Have to Say About Wearing Masks

Hamsters, which are naturally susceptible to SARS-CoV-2, have been used to test the effectiveness of masks in combating the spread of the novel coronavirus.   Fifteen years ago, researchers showed that Syrian hamsters could be easily infected with the SARS-CoV-1 coronavirus, the vector for SARS, a disease related to COVID-19. When recently tested against SARS-CoV-2, these rodents also showed susceptibility to the disease. After infection, the hamsters appear to lose weight, become lethargic, have ruffled fur, adopt a hunched posture, and develop rapid, labored breathing. SARS-CoV-2 is found in large quantities in the animals’ lungs and intestines. These clinical manifestations are reminiscent of upper and lower respiratory tract infections in humans. This animal model can therefore facilitate the study of the virus’s mechanisms, its infection, and its transmission. Researchers at the University of Hong Kong have thus chosen this rodent to study the role of mask-wearing in virus transmission. This research is among the first to examine the role of mask-wearing in preventing symptomatic or asymptomatic carriers of the COVID-19 virus from infecting others. The researchers placed cages containing previously infected hamsters near those of healthy animals. Surgical masks were placed between the two cages, with airflow directed from the cage of the infected animals toward the cage of the healthy ones. Tests on the hamsters revealed that the use of masks reduces the spread of the coronavirus by 60%. Two-thirds of the healthy hamsters became infected within a week when masks were not in place. This infection rate drops to 15% when masks are placed over the cage of the infected animals and to 35% when they are placed over the cage of the healthy hamsters. Infected individuals wearing masks were also found to have a lower viral load than those without masks. This study appears to support the widespread use of masks.