Bluewater Health officials are "deeply concerned" about a COVID-19 outbreak at University Hospital.
The London hospital is not accepting admissions to any medical floors for the next week.
Bluewater Health President and CEO Mike Lapaine said there hasn't been any pushback from London yet on the flow of patients between Sarnia and University hospital.
"We're monitoring it very closely and it's very concerning for us," said Lapaine. "We have patients that go back and forth to London, I'm thinking of cancer patients, cardiac patients, and neuro patients. There's a lot of reasons that patients go back and forth to London. Blocking access in London is of grave concern for us. So, it's a deeply concerning development."
The outbreak at University Hospital, declared November 10 on the fourth-floor medicine unit, was expanded on Tuesday to all medical floors.
There are 34 linked cases among patients and staff at the hospital as well as one related death.
-With files from Sue Storr