MILWAUKEE — Days after confirming that President Joe Biden had tested negative for COVID-19 after recently contracting the virus, White House physicians this past weekend confirmed the president had again tested positive for it, prompting no shortage of interest into what have been dubbed “rebound” cases.

“Research is still being done to figure out why this is happening,” Dr. Dan Shirley, Medical Director of Infection Prevention at UW Health, said. “Most of these ‘rebound’ phenomena are found by testing or some mild symptoms that recur.”

Biden had taken the anti-viral treatment Paxlovid to help to limit his symptoms, and Shirley said many researchers are now looking into the link between Paxlovid and similar "rebound" cases of COVID.

Research shows a small amount of those prescribed Paxlovid can experience a "rebound" case of COVID-19. According to the CDC, most "rebound" cases remain mild.

“Most of the time, this is noticed when someone takes the drug Paxlovid,” Dr. Shirley added. “It’s assumed this is a contagious situation, so if this happens to you I think the general recommendation all along would be if you start feeling sick again after you seem to have recovered from COVID, you should treat yourself like it might be COVID again and re-isolate.”

You can watch the full interview above.