(CNN)The antiviral medication Paxlovid appears to be most effective in people whose age or underlying health puts them at high risk for becoming severely ill with Covid-19, but it appears to be less effective for average-risk adults, drugmaker Pfizer reported.
Paxlovid loses luster in people who aren't at high risk from Covid-19, Pfizer study finds
The news is "good timing, because there is a lot of Covid out there," said Dr. Michael Charness, an internist and neurologist at Boston's Veterans Affairs Healthcare System. Although the drug's emergency use authorization from the US Food and Drug Administration permits only prescribing to high-risk patients, "there is probably a more relaxed standard in the community."
"I think this provides some clarity," said Charness, who was not involved in the research.
In a study designed to test Paxlovid in "standard-risk" adults, Pfizer enrolled more than 1,100 people ages 18 and up. To join the study, they had to be within five days of a positive Covid-19 test and had to have symptoms. People who were fully vaccinated could join the study if they had at least one underlying risk factor for progression of their illness, such as obesity or suppressed immune function.
Half of this group was assigned to take Paxlovid twice daily for five days; the other half got a placebo.
In a news release Tuesday, Pfizer said Paxlovid was not proven to reduce all Covid-19 symptoms for at least four consecutive days in these average-risk participants. This was the main question being tested by the study.
A second question -- whether Paxlovid could reduce the need for medical care -- found significant benefit. The medication decreased health care visits for Covid-19, as measured in hospitalizations, emergency department or urgent care visits, or telehealth visits, compared with the placebo group.
"It helps to answer a question many of us have had about whether or not there is a reason to use for Paxlovid for our healthier patients," said Dr. Cassandra Pierre, an infectious disease specialist and medical director of public health programs at Boston Medical Center.
Pierre, who also was not involved in the study, said it wouldn't change what she does; she generally doesn't prescribe Paxlovid unless her patient seems to be at high risk for Covid-19 complications.
But it does help her answer questions for people who might be wondering whether taking it wouldn't help them feel better sooner and get back to their daily life faster.
"We see no benefit at this time from taking it, so I would recommend that they don't at this point," she said.
Pierre said many important questions about Paxlovid are still unanswered: Can it decrease the risk of long Covid, for example? Can it cut the chances that an infected person could pass it to someone else? She'll keep watching for those.
In the meantime, Pierre said, she'd probably tell her vaccinated and boosted patients who catch Covid-19 to rest and treat their symptoms as they would with any respiratory virus, with over-the-counter pain relievers and herbal tea.