Bill Bryan, head of science and technology at the Department of Homeland Security, speaks about the coronavirus in the James Brady Press Briefing Room of the White House on April 23.
Bill Bryan, a senior official performing the duties of the under secretary for Science and Technology (DHS), explained during Thursday’s briefing that experiments with coronavirus samples indicate that the virus does not do well under sunlight, in warm temperatures or in humid conditions.
“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 favorable to the virus,” Bryan told reporters.
Earlier this month, members of a National Academy of Sciences’ Standing Committee on Emerging Infectious Diseases and 21st Century Health Threats told the White House in a letter that it doesn’t look like coronavirus will go away once the weather warms up.
“There is some evidence to suggest that [coronavirus] may transmit less efficiently in environments with higher ambient temperature and humidity; however, given the lack of host immunity globally, this reduction in transmission efficiency may not lead to a significant reduction in disease spread without the concomitant adoption of major public health interventions,” according to the letter.
The letter pointed out that in the real world, the virus is still transmitting in countries with warm weather.
“Given that countries currently in ‘summer’ climates … are experiencing rapid virus spread, a decrease in cases with increases in humidity and temperature elsewhere should not be assumed,” according to the letter.
At the briefing, Bryan said that higher temperatures and humidity causes the virus to die more quickly. “The virus is dying at a much more rapid pace just from exposure to higher temperatures and just with exposure to humidity. … You inject sunlight into that, you inject UV rays into that, … the half-life goes from six hours to two minutes,” he said.
Bryan specifically discussed how the droplets of saliva with coronavirus are fairing under warm and humid conditions.
“So in summary, within the conditions we’ve tested to date, the virus in droplets of saliva survives best indoors and in dry conditions. The virus does not survive as well in droplets of saliva — and that’s important, because a lot of testing being done is not necessarily being done, No. 1 with the Covid-19 virus, No. 2, with saliva or respiratory fluids. And third, the virus dies the quickest in the presence of direct sunlight under these conditions,” he said.
Bryan said bleach will kill the coronavirus in five minutes and isopropyl alcohol will kill the virus in 30 seconds.
“You rub it and it goes away even faster,” he added.
President Trump said he suggested to Bryan figuring out ways to use UV rays or disinfectant on human beings to treat individuals with coronavirus.
“Suppose that we hit the body with a tremendous, whether it’s ultraviolet or just very powerful light and I think you said that it hasn’t been checked and you’re going to test it,” Trump told Bryan. “Suppose you can bring the light inside the body.”
He added, “And then I see the disinfectant where it knocks it out in one minute. Is there a way we can do something like that by injection inside or almost a cleaning … it would be interesting to check that.”