At his rally in Alabama on Saturday night, Donald Trump heard the unusual sound of booing and jeering aimed his way, after he told supporters: “I recommend taking the vaccines.”

The former president was speaking in Cullman, Alabama, a city struggling to cope with Covid-19 cases and hospitalisations.

Like other states home to resistance to vaccinations and other public health measures often stoked by Republican leaders, Alabama is currently at the mercy of the Delta variant of the coronavirus.

“I believe totally in your freedoms,” Trump said. “I do, you’re free, you got to do what you have to do.

“But I recommend taking the vaccines. I did it, it’s good, take the vaccines.”

Trump was vaccinated while in office, having been hospitalised with Covid-19 last October. He has told supporters they should follow suit.

In Alabama, responding to boos and jeers, he said: “That’s OK. That’s all right. That’s good, you got your freedoms.

“But I happen to take the vaccine. If it doesn’t work, you’ll be the first to know. OK.”

Ahead of the Trump rally, local authorities said they feared a super-spreader event.

According to AL.com, Luke Satterfield, an attorney for the city, said: “We want to prevent as many non-Covid related things as possible, so our hospital can use its resources to focus on the pandemic and its variants. We don’t want to put any extra strain on them.”

As the Delta variant surges across the US, hospitalisations and deaths from Covid-19 are overwhelmingly among the unvaccinated.

In Alabama, the state hospital association said this week that 85% of hospitalized Covid-19 patients were unvaccinated. Alabama is also seeing a surge in Covid cases among children. The state this week had 50 children hospitalized with Covid-19.

Dr Karen Landers, a pediatrician with the Alabama health department, told the Associated Press she was “very concerned … children can and do contract and spread Covid-19”.

Elsewhere on Saturday the Republican governor of Texas, another state struggling with Covid cases and political turmoil over public health mandates, said he had tested negative for Covid-19 four days after testing positive.

“I’m told that my infection was brief and mild because of the vaccination that I received,” Greg Abbot said, in a video posted to Twitter. “So I encourage others who have not yet received the vaccination to consider getting one.”