Ontario's first COVID-19 field hospital on the grounds of Joseph Brant Hospital opens for patients. (Joseph Brant Hospital/Twitter)

An Ontario field hospital built during the start of the pandemic will begin taking patients this week as a worsening wave of COVID-19 infections pushes the health-care system to its limits.

The Burlington, Ont., facility on the grounds of Joseph Brant Hospital was ready to treat patients as of Monday, the hospital said. Hospitals in the region were working Tuesday to identify patients ready for transfer.

The field unit was built in April as part of the hospital network's capacity plan -- the first of several to go up across the province during the pandemic.

Hospital CEO Eric Vandewall said it was deemed time to use the 73-bed all-season facility to keep scheduled surgeries and important services running as acute care units reach their full capacity with COVID-19 patients.

"The (field unit) is, in a sense, an insurance policy, and one that you hope you never have to use," Vandewall said in an interview Tuesday.

"We've very fortunate to have the resource. It's troubling obviously, that we're having to use the resource at this time."

COVID-19 infections have put increased pressure on hospital capacity across the southern Ontario region that includes Hamilton, Niagara, Haldimand, Brant and Burlington.

"Our healthcare system is being stretched to its limits," Rob MacIsaac, president of Hamilton Health Sciences, said in a statement Monday.

Hospitals are identifying patients this week whose care has progressed enough to be treated at the field unit, after consulting with their families.

UPDATE: JBH’s Pandemic Response Unit – the 1st of its kind built in ON – is welcoming its 1st #COVID19 patients this week, in response to a heightened need for COVID-19 care & increasing pressure on regional hospital capacity. READ: https://t.co/7rFxneK3TL #burlon #hamont pic.twitter.com/PKTqcpZqUC

— Joseph Brant Hospital (@Jo_Brant) January 4, 2021

Staffing has been a challenge during this wave of infections, Vandewall said, but there are currently enough staff for 30 beds, with plans to increase capacity this month if necessary.

Family doctors, nurses, physiotherapists and community care workers are among those staffing the field unit.

Other field hospitals in Ontario have been used for different pandemic-related operations.

London, Ont.,'s vaccination program is being deployed at the London Health Sciences Centre's field hospital unit, located at the Western Fair District Agriplex.

The hospital put out a call for nurses this week to assist with vaccination efforts at the facility.

This report by The Canadian Press was first published Jan. 5, 2021.