President Trump’s chief of staff has revealed that the president’s “blood oxygen level had dropped rapidly” prior to his hospitalization on Friday. Speaking to Fox News’ Jeanine Pirro late Saturday, Mark Meadows largely echoed comments he had reportedly been caught giving reporters anonymously earlier in the day about Trump’s “very concerning” vitals, but this time he insisted the president has made “unbelievable improvement” since then—while noting with laughter that Trump was probably watching his interview. “The biggest thing that we see is that with no fever now, and with him doing really well with his oxygen saturation levels … yesterday morning we were real concerned by that. He had a fever and his blood oxygen level had dropped rapidly,” he said.

Trump’s doctor had conceded a short time earlier that the president is “not yet out of the woods” despite “having made substantial progress” since his diagnosis. “This evening he completed his second dose of Remdesivir without complication. He remains fever-free and off supplemental oxygen with a saturation level between 96 and 98% all day,” Dr. Sean Conley said in a statement released by the White House. Apparently seeking to ease fears about his condition following the report of “very concerning” vitals, Conley went on to say the president “spent most of the afternoon conducting business, and has been up and moving about the medical suite without difficulty.” The medical team “remains cautiously optimistic” even though Trump is not yet in the clear, he said. The statement came shortly after Trump himself appeared in a four-minute video on in which he said he believed he would “be back soon” and was “starting to feel good.”