Biden, 79, contracted the virus a second time three days after coming out of isolation from his first bout with COVID-19, reported July 21.
Rare cases of rebound have been documented in a small minority of those, like Biden, who were prescribed the antiviral drug Paxlovid, which has been shown to reduce the risk of serious illness and death from the virus in those at the highest risk.
During his first breakout with the virus, Biden’s main symptoms were a runny nose, fatigue and a loose cough, his doctor said at the time. During his rebound case, O’Connor said only Biden’s cough returned and was “almost completely resolved” by Friday.
Regulators are still studying the prevalence and virulence of rebound cases, but the Centers for Disease Control and Prevention in May warned doctors that it’s been reported within two to eight days of the initial negative test for the virus.
“Limited information currently available from case reports suggests that individuals treated with Paxlovid who experienced COVID-19 rebound have had mild illness; there are no reports of serious illness,” the agency said at the time.