The epidemic of severe acute respiratory syndrome (SARS) is freezing up biomedical research in Toronto, Canada, as medical-school administrators are forced to reduce access to hospital buildings. And the situation is being eyed nervously by colleagues in the United States and elsewhere, who fear similar consequences as the spread of the mystery illness continues.

“When they started taking our temperatures we knew it was getting serious,” says Stephen Scherer, a geneticist at Toronto's Hospital for Sick Children. But for Scherer and other scientists at Toronto's research hospitals, a nurse's check-up as they arrive each day is just the start of the problem.

To contain the spread of the disease from sufferers admitted to the hospital and staff working there, all non-essential staff at Scherer's institute and the nearby Mount Sinai Hospital are being encouraged to stay at home.

Researchers determined to get to work must join queues at the hospital's entrances, pass a SARS screening test and wear a surgical mask while in the hospital. Meetings of researchers are banned, even outside hospital grounds.

“There's been massive disruption,” says Michael Tyers, a cell biologist at Mount Sinai's Samuel Lunenfeld Research Institute. “Many of the projects in my lab have been compromised.”

Until researchers figure out the exact cause of SARS, and how it spreads, disruption is likely to continue. The needs of researchers will take second place to the need to contain the disease, says infection-control specialist Mark Loeb of McMaster University in Hamilton, Ontario, who is advising Toronto's hospitals on controlling SARS.

Many researchers who have no direct contact with patients still like to rub shoulders with clinical staff, and administrators think that this helps to assure the research's clinical relevance. But the SARS outbreak is giving some researchers second thoughts. “I'm starting to question the point of working in a research hospital,” says Tyers.

Cell-signalling researcher Tony Pawson, research director of the Samuel Lunenfeld institute, says he is optimistic that the SARS outbreak will abate before researchers walk out. “But it raises a lot of issues about hospitals being used as thoroughfares,” he says.