The US Centers for Disease Control and Prevention, or CDC, has issued a "do not travel" status for Canada as the country wrestles with a rising tide of coronavirus cases in a third wave of the disease.

"Because of the current situation in Canada, even fully vaccinated travelers may be at risk for getting and spreading COVID-19 variants and should avoid all travel to Canada," the CDC stated on its website.

The CDC placed Canada at the highest risk level－Level 4－or "very high".

The Canada-US border has been closed to people traveling for nonessential visits since March 2020 to at least May 21, 2021, to help limit the spread of COVID-19.

The per capita rate of new COVID-19 cases now exceeds that of the US for the first time.

Canada is undergoing a severe third wave of the pandemic, driven by new, more transmissible coronavirus variants that are threatening to overwhelm the country's healthcare systems. Many provinces are locking down after reporting record-high daily cases.

Record high

Ontario, Canada's most populous province, recorded 4,812 more cases of COVID-19 last Friday, the most yet on a single day, marking the third straight day of new peaks. Critical Care Services Ontario said 74 more people with COVID-19 were admitted to ICUs last Thursday, the most on one day in the province.

"I've never shied away from telling you the brutal, honest truth," Ontario Premier Doug Ford told the media on Friday. "We're losing the battle between the variants and vaccines.… We're on our heels."

Ontario's COVID-19 science advisory group said without stronger system-level measures and immediate support for essential workers and high-risk communities, high case rates will persist through the summer.

To combat a worsening outbreak that is pushing the province's healthcare system to the breaking point, Ford announced on Friday a new stay-at-home order for a minimum of six weeks until May 20; restricting outdoor gatherings; and boosting enforcement powers for police.

New infection modeling predicts Ontario could see as many as 10,000 new daily cases by the end of June if the current trajectory holds. A six-week stay-at-home order with an average of 100,000 vaccinations per day "is the only way to flatten the curve", the modeling shows.

Ontario has announced plans to make coronavirus vaccines more accessible and has lowered the age for vaccine eligibility from 55 to 40, effective on Tuesday, and 35 in some hot spots.

The federal government promised it would help send nurses and doctors from other provinces to help in Ontario hospitals, where ICU admissions continue to grow.

Prime Minister Justin Trudeau pledged to send more healthcare workers to Ontario and boost rapid testing to help the province through the third wave.

"We are mobilizing federal healthcare workers from across government departments to deploy to the frontlines in Ontario and specifically the greater Toronto area where the situation is most critical," Trudeau said in a video posted on Twitter.

Agencies contributed to this story.