During an Oct. 7 appearance on CNN, Robert Wachter, MD, chair of the Department of Medicine at the University of California, San Francisco, offered his assessment of what’s ahead for the president’s COVID case. “The absence of fever and the absence of symptoms when someone is on steroids is a little bit dicey to hang your hat on because the steroids can make fever go away and make people feel better even though they are still kind of sick,” Wachter said. “Patients often feel invincible on steroids, but then they get to the top and then there’s that reckoning and he was clearly short of breath.” Wachter added: “He is not out of the woods. It won’t really be until next week that he would be getting to the end of the period during which we worry about a significant deterioration and compromise of his breathing.” In an earlier report on Oct. 5, Wachter told BuzzFeed News that things could “go in a lot of different directions. There has got to be a least a 30 percent chance that he will get worse.” COVID-19 appears to have two distinct phases—the viral infection that causes the illness itself, and then in some cases, a subsequent overreaction of the body’s immune system, called a cytokine storm, which can cause serious problems. If left unchecked, this can lead to severe lung damage, multiple organ failure, and even death. “It’s the immune system trying hard to attack the virus as an external invader but also then attacking your own body,” Wachter told CNN. “That’s rationale for giving him the steroids. It’s designed to tamp it down.” And for more on Trump’s COVID case, check out These Are All the COVID Treatments Trump Has Tried.ae0fcc31ae342fd3a1346ebb1f342fcb Because of a potential cytokine storm, patients need to be closely monitored after leaving the hospital. A week after first feeling ill, patients can experience a second wave of symptoms. “Clinicians should be aware of the potential for some patients to rapidly deteriorate one week after illness onset,” the Centers for Disease Control and Prevention (CDC) warns in its guidance. “Week two is the worst because of the fact that you have the inflammatory response to the virus,” Cedric Dark, MD, an assistant professor of emergency medicine at Baylor College of Medicine, told BuzzFeed News. And for more symptoms to look out for, know that There’s an 80 Percent Chance You Have COVID If You Have This Symptom. In Conley’s Oct. 7 report, he also noted that “the president’s labs demonstrated detectable levels of SARS-CoV-2 IgG antibodies,” referring to the virus that causes COVID-19. But Wachter told CNN that doesn’t tell the full story. “In everybody who has COVID and survives, at some point, you begin to develop antibodies against the virus,” he explained. “The timing varies a little bit but it’s expected that that would happen. It doesn’t say very much about what his course is likely to be, because the antibodies themselves don’t necessarily guarantee that he will have a benign course of COVID.” And for more on the president’s COVID battle, sign up for our daily newsletter. Wachter remains somewhat optimistic about the president’s status, but he’s not ruling out a potentially deadly outcome. “Every day he goes on and doesn’t deteriorate, his probability of a bad outcome goes down,” he explained. “But at this point, you would still say, if you took the overall numbers of patients with COVID, as severe as he had, with the risk factors he had, he still has a significant chance, probably more than 1 in 10, of dying of this episode. So it’s nothing to be taken lightly.” And for more on the White House outbreak, check out This One Detail Has Doctors Worried Trump’s COVID Case Could Be Severe.