Health experts are questioning the length of Pfizer's antiviral treatment, as COVID-19 rebounds seem to exceed "rare" status, according to Time.
Paxlovid is a five-day, two-drug regimen intended for those at high-risk for severe COVID-19, such as older populations and immunocompromised people. When the FDA approved it in December, Pfizer said rebounds — when a person takes Paxlovid, tests negative, then tests positive for COVID-19 again — happened among 1 to 2 percent of its study participants.
But, after high-ranking people including President Joe Biden and Anthony Fauci, MD, had rebound infections after Paxlovid, some virologists are calling for Pfizer to lengthen the treatment past five days.
"The virus is rather persistent," David Ho, MD, a microbiology and immunology professor at New York City-based Columbia University, told Time. "And we believe that five days of treatment is not enough to have that form decay so that it's nonexistent at the end of those five days."
Dr. Ho is studying the strength of extending Paxlovid's course to seven to 10 days, which early results show to increase its efficacy 10-fold, according to Time.
There isn't much data about the frequency of Paxlovid rebounds. The CDC issued a warning in late May about rebounds, but a Mayo Clinic study in June found them to be rare, with less than 1 percent of study participants experiencing a rebound. A Pfizer spokesperson told Time the pharmaceutical company is working to set up a trial to further study Paxlovid rebounds.