Biden tested negative for Covid-19 on Sunday

The President took the test independently of press secretary Jen Psaki's positive result, which she disclosed in a statement Sunday afternoon. The test was required for entry into the United Kingdom, where Biden is en route for the United Nations Climate Summit, known as COP26, in Glasgow, Scotland.

Psaki said on Sunday she last saw Biden five days before, "when we sat outside more than six-feet apart, and wore masks."

The White House announced Thursday that Psaki would no longer join Biden on his trip abroad "for at least the first few days," citing a family emergency. White House deputy press secretary Karine Jean-Pierre instead traveled with the President.

It's unlikely Psaki could have infected Biden with Covid-19, several physicians told CNN on Sunday.

"Based on the timeline of Ms. Psaki's testing negative for multiple days following her last encounter with President Biden (which was also outside and masked, therefore very low risk in and of itself), it is virtually impossible for her to somehow have infected the President," Dr. Leana Wen, a CNN medical analyst and former Baltimore City health commissioner, told CNN.

Infectious diseases expert Dr. Peter Hotez of the Baylor College of Medicine also said he felt Biden was well protected.

"Well he's 3 times vaccinated so he should be good, unless he has immunodeficiencies we don't know about," Hotez told CNN by email.

And Dr. Jonathan Reiner, a professor of medicine at George Washington University, also pointed to the fact that the most recent interaction between Psaki and Biden had been outside.

"Transmission outside is much less likely than transmission inside. Also, she and the President were both wearing masks. That would further reduce the likelihood of transmission. Also, remember, the President had been boosted. Recent data from Pfizer shows the third dose, what we had been calling the booster, restores that vaccine's efficacy to about 95% so I am sure the President also will be fine," Reiner told CNN's Jessica Dean.

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