The northwestern state’s health department said it had enacted the measure because of “the massive increase of Covid-19 patients requiring hospitalisation” which had “exhausted” existing resources.

“The situation is dire,” said health department director Dave Jeppesen in a statement.

“We don’t have enough resources to adequately treat the patients in our hospitals, whether you are there for Covid-19 or a heart attack or because of a car accident,” he added, calling on more Idaho residents to get vaccinated.

The department’s statement explained that under the rationing guidelines, patients admitted to hospital may find beds unavailable or be treated in repurposed settings like conference rooms.

What’s more, “someone who is otherwise healthy and would recover more rapidly may get treated or have access to a ventilator before someone who is not likely to recover.”

Only 46% of Idaho’s population of nearly 1.8 million have received one or more doses of a Covid-19 vaccine, according to the Covid Act Now tracker.

This puts it at the bottom of the table among 53 US states or territories. For reference, 63% of the US population has received one or more doses, with table-topping Puerto Rico at 77%.

More than 630 people are hospitalised with Covid in the state, compared to around 90 in early July. Around 20 are dying per day, equal to the worst surge seen in December, and the figure could rise further.

Vaccines, as well as other Covid mitigation measures like masks and distancing, are politically polarising issues in the US, with uptake much lower in conservative-leaning regions.

Former president Donald Trump carried Idaho with 64% of the popular vote compared to Joe Biden’s 33% in the 2020 election.