Bay Area COVID patients flag 'Paxlovid rebound' after taking antiviral treatment - San Francisco Chronicle

As the number of Americans taking the Pfizer drug skyrockets, many people are reporting similar “rebound” after taking the drug — including some vaccine scientists and doctors who’ve documented their experiences on Twitter.

All known cases of Paxlovid viral rebound appear to have been resolved without patients needing hospitalization, say doctors who prescribe the drug and researchers who are studying the issue.

They say if someone is eligible for Paxlovid, the patient should still get it, despite the potential of experiencing rebound symptoms, because it’s living up to its promise by indeed keeping people out of the hospital.

The Paxlovid rebound phenomenon is an example of what happens when a new medication — probably the most closely watched drug in recent memory, second only to COVID vaccines — starts to get used widely in the real world and elicits outcomes that may not have been observed during clinical trials at such high levels.

In Pfizer’s clinical trials, it occurred in 2% of the people who took Paxlovid.

“We’ve all heard anecdotes of patients we’ve taken care of that experience this, so it’s clearly a phenomenon,” said Jagannathan, who has prescribed Paxlovid to 25 to 30 patients and observed rebound in two of them.

Food and Drug Administration are tracking rebound cases for further study.

This could mean that instead of the five-day course currently authorized by the FDA, people may need to take the drug for longer, or at a different dosage.

The study, which was posted on a pre-print site this week, looked at three vaccinated and boosted adults who took Paxlovid, including one who experienced rebound.

“There’s likely going to be studies to see if people need 10 days instead of five days to try to prevent that rebound from occurring.”.

Another small study, initially posted in late April and updated last week by the VA Boston Health System, also suggests the reason for relapse isn’t because the virus mutated after patients took Paxlovid.

Now, it’s people infected with omicron and omicron subvariants who are taking the drug, including many who are vaccinated.

It could also be that omicron and its subvariants lead to a longer period of viral shedding than delta, so people may now need a longer course than five days.