Donald Trump has stunned viewers by suggesting people could receive injections of disinfectant to cure the coronavirus, a notion one medical expert described as “jaw-dropping”.

At Thursday’s White House coronavirus taskforce briefing, the US president mused on new government research into how the virus reacts to different temperatures, climates and surfaces.

Trump said: “And then I see the disinfectant, where it knocks it out in a minute. One minute! And is there a way we can do something like that, by injection inside or almost a cleaning. Because you see it gets in the lungs and it does a tremendous number on the lungs. So it would be interesting to check that. So, that, you’re going to have to use medical doctors with. But it sounds interesting to me.”

Dr Deborah Birx, the taskforce response coordinator, remained silent. But social media erupted in outrage at the president, who has a record of defying science and also floated the idea of treating patients’ bodies with ultraviolet (UV) light.

Several doctors warned the public against injecting disinfectant or using UV light and a leading household cleaner manufacturer urged users not to inject it into their bodies.

Reckitt Benckiser, the British-based maker of Dettol and Lysol, said in a statement: “We must be clear that under no circumstance should our disinfectant products be administered into the human body (through injection, ingestion or any other route).”

Political commentators joined the condemnation. Robert Reich, a professor of public policy at the University of California at Berkeley and a former labor secretary, tweeted: “Trump’s briefings are actively endangering the public’s health. Boycott the propaganda. Listen to the experts. And please don’t drink disinfectant.”

Walter Shaub, the former director of the Office of Government Ethics, added: “It is incomprehensible to me that a moron like this holds the highest office in the land and that there exist people stupid enough to think this is OK. I can’t believe that in 2020 I have to caution anyone listening to the president that injecting disinfectant could kill you.”

Trump was already facing a backlash over his championing of hydroxychloroquine, an anti-malaria drug, as a therapy for the coronavirus, a quixotic effort amplified by the conservative network Fox News. Research has found no evidence that it is beneficial and a government vaccine expert has claimed he was fired for limiting its use.

Hydroxychloroquine: how an unproven drug became Trump’s coronavirus 'miracle cure' Read more

Undeterred, on Thursday Trump showcased an “emerging result” from Department of Homeland Security research that indicates coronavirus appears to weaken more quickly when exposed to sunlight, heat and humidity, raising hopes that it could become less contagious in summer months.

Bill Bryan, the acting homeland security undersecretary for science and technology, said at the briefing: “Our most striking observation to date is the powerful effect that solar light appears to have on killing the virus – both surfaces and in the air. We’ve seen a similar effect with both temperature and humidity as well, where increasing the temperature and humidity or both is generally less favourable to the virus.”

Researchers found that the virus survives best indoors and in dry conditions, and loses potency when temperatures and humidity rise. Bryan said: “The virus dies the quickest in the presence of direct sunlight under these conditions.”

He showed a slide summarising the results of the experiment that were carried out at the National Biodefense Analysis and Countermeasures Center. He also said tests had been carried out with disinfectants and isopropyl alcohol, specifically in saliva or in respiratory fluids.

“And I can tell you that bleach will kill the virus in five minutes; isopropyl alcohol will kill the virus in 30 seconds, and that’s with no manipulation, no rubbing – just spraying it on and letting it go. You rub it and it goes away even faster. We’re also looking at other disinfectants, specifically looking at the Covid-19 virus in saliva.”

Facebook Twitter Pinterest Trump prompted awkwardness when he asked if Dr Birx had heard of heat and light in relation to coronavirus. ‘Not as a treatment,’ she said. Photograph: REX/Shutterstock

Trump seized on the findings to refer back to a claim he made on 14 February that warm weather might kill the virus, like common flu, noting that he had been criticised by the media. “I think a lot of people are going to go outside, all of a sudden, people that didn’t want to go outside,” he said.

And he asked Bryan an extraordinary question: “So I asked Bill a question that probably some of you are thinking of, if you’re totally into that world, which I find to be very interesting. So, supposing we hit the body with a tremendous – whether it’s ultraviolet or just very powerful light – and I think you said that that hasn’t been checked, but you’re going to test it.

“And then I said, supposing you brought the light inside the body, which you can do either through the skin or in some other way, and I think you said you’re going to test that too. It sounds interesting.”

Bryan responded: “We’ll get to the right folks who could.”

UV rays are an invisible type of radiation that can penetrate and damage skin cells, and overexposure can cause skin cancer. How much sunlight would be needed to have an effect on the coronavirus is unknown. The virus has caused heavy death tolls in warm-weather areas such as Louisiana and Florida, and Singapore has seen a recent surge in cases.

A Washington Post reporter asked if it was dangerous for Trump to make people think they would be safe by going outside in summer heat. The president turned to Bryan and said: “I would like you to speak to the medical doctors to see if there’s any way that you can apply light and heat to cure.

“Maybe you can, maybe you can’t. Again, I say, maybe you can, maybe you can’t. I’m not a doctor.”

In a cringeworthy moment, he asked Birx if she had ever heard of heat and light in relation to the coronavirus. “Not as a treatment,” she said, explaining that the body responds to the virus with a fever.

When the Post reporter pressed further, Trump retorted: “I’m the president and you’re fake news … I’m just here to present talent, I’m here to present ideas.”

Experts questioned why the homeland security report had been promoted at the briefing. Dr Irwin Redlener, the director of the Center for Disaster Preparedness at Columbia University, told MSNBC: “Everything that this scientist talked about from homeland security was basically incoherent, nonsensical, not really supported by evidence and really quite contrary to a lot of things that we do know about some of the things he was saying.

“First of all, people do get Covid, have been getting Covid in warm climates. Second of all, this issue with UV light is hypothetical, but also UV light can be very harmful and we did not hear anything resembling a balanced discussion of what the evidence is for and against UV light, but it’s certainly not ready for prime time.”

He added: “The very fact that the president actually asked somebody about what sounded like injecting disinfectants or isopropyl alcohol into the human body was kind of jaw-dropping.”