TORONTO -- Canadian residents are allowed to head to the United States for a COVID-19 vaccine and avoid quarantine on return if they meet some straightforward conditions, the Public Health Agency of Canada confirms.

Those conditions include having a note from a licensed health-care provider in Canada that the inoculation is medically necessary, and written proof from the licensed U.S. vaccine provider.

Quarantine regulations passed by the federal government contain an exemption for essential medical services obtained abroad. A coronavirus shot, the agency says, falls under that definition.

The exemption offers people within driving range of border states awash in vaccines a relatively simple way to get a coveted shot quickly. While supplies are ramping up in Canada, distribution in many areas remains tenuous and age and other eligibility limits remain in place.

Information on the regulations and exemption, created by federal cabinet and contained on the government's website, was confirmed by the Public Health Agency of Canada in an email to David Musyj, head of the Windsor Regional Hospital in the border city of Windsor, Ont.

Musyj had pressed Health Canada for answers after noting that people could easily drive over to Detroit for a shot, but having to isolate for 14 days on return would be a major obstacle.

"It does verify our interpretation of the current order in council/website information is accurate -- that a COVID-19 vaccine is an 'essential medical service or treatment,' Musyj said. "It makes it clear the exemption is permissive."

However, public health also said in a written exchange with Musyj that crossing the border -- which remains closed to non-essential travel -- for a vaccine would not be licence to tack on shopping or other activities. In addition, to qualify for an exemption, the trip has to be in a private vehicle but can include a support person.

"Very clear: You need to go to the appointment only and return immediately," Musyj said. "Cannot stop anywhere else for anything."

On return, health authorities said, quarantine-exempt travellers must wear a mask in public spaces at all times and keep a list of close contacts and places visited for 14 days.

Importantly, Health Canada noted U.S. border agents have final say on who they let in, and that it is up to returning travellers to provide the required documents to Canada Border Services agents for a final decision on a quarantine exemption.

"The onus is on the traveller to clearly demonstrate they meet an exemption under the order in council," the public health agency said.

Musyj said he was still pushing for federal approval to allow an organized effort to retrieve surplus vaccines from Detroit and bring them back to Canada for use here. The same vaccines produced in Kalamazoo, Mich., are also distributed in Canada but demand in the U.S. has lagged supply.

The federal government has said millions of COVID-19 inoculation doses are set to start arriving in the coming days, but supplies remain limited in many areas.

This report by The Canadian Press was first published May 18, 2021.