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Paxlovid lowered COVID hospitalizations, deaths in vaccinated adults over 50, Mass General Brigham study says

The study from Mass General Brigham also said some younger patients can benefit from the drug

The anti-viral drug Paxlovid.Stephanie Nano/Associated Press/file

Paxlovid, the drug used to treat COVID-19 infections, reduced hospitalizations and death in a vaccinated population of adults over the age of 50 by 44 percent, according to a new study from Mass General Brigham researchers.

The study, published last week in the journal Annals of Internal Medicine, analyzed “observational data” from nearly 45,000 patients diagnosed with COVID-19 between January and July, Mass General Brigham said in a statement.

Paxlovid had been shown in previous clinical trials to reduce hospitalization and death among high-risk, unvaccinated patients by 88 percent. But the new study shows the drug can also benefit people who are vaccinated, researchers said in the statement.


Researchers believe the lower level of risk reduction may come down to different contexts: patients in the Mass General Brigham study had high levels of immunity and a resulting lower risk of severe disease. But among the “small minority” of patients in the study who had received fewer than three vaccine doses, hospitalizations were reduced by 81 percent, a comparable rate to past clinical trials.

The results could inform efforts to reduce COVID-19 hospitalizations during an expected winter surge, Mass General Brigham said.

When Paxlovid “was first becoming available for treating COVID-19, providers and patients asked important questions about who might benefit the most from this intervention, which can pose complications under certain circumstances,” Dr. Scott Dryden-Peterson, medical director of Mass General Brigham’s COVID outpatient therapy and a corresponding author of the study, said in the statement.

“The observed rate of hospitalization or death was low (1 percent) among outpatients diagnosed with COVID-19, but we found that Paxlovid was still associated with a proportional reduction of risk for hospitalization of about 50 percent across patient groups with different baseline risk levels,” Dryden-Peterson said.

Dr. Ann Woolley, associate clinical director of transplant infectious diseases and Brigham and Women’s Hospital and a senior author on the study, said the research is crucial to Mass General Brigham’s COVID-fighting strategy.


“The impetus for this study was in needing to figure out how this therapy fits into Mass General Brigham’s response to COVID-19,” Woolley said in a statement. “This study incorporated and built on existing systems and has allowed us to feel, programmatically within the Mass General Brigham system, and clinically within Infectious Diseases, that we were doing the right thing by prescribing Paxlovid to eligible patients.”

In the coming months, researchers expect Paxlovid will be more important in the fight against the virus, since there are no longer any monoclonal antibody therapies that work against the circulating COVID strains in the United States.

“These data have been helpful as we prepare for a winter surge,” Dryden-Peterson said. “Our findings suggest that Paxlovid can save lives, and it can have a real impact on keeping hospital beds available for the treatment of other conditions. The opportunity to prevent COVID-19 hospitalizations is not there unless people know that they’re positive, so we have ongoing efforts to do outreach, make testing available, and communicate to the highest-risk patients that they may benefit from Paxlovid or another antiviral treatment option.”

Asked Tuesday if Paxlovid can shorten illness duration or make symptoms milder, Dryden-Peterson said in an e-mail that many patients taking Paxlovid do report feeling better faster, although the study didn’t examine that question.


“A blinded trial done by the manufacturer in lower risk patients to answer this question ... did not find a difference in recovery unfortunately,” Dryden-Peterson said.

Some younger patients can benefit from Paxlovid as well, he added.

“Paxlovid should certainly be used by younger people with immunocompromise or other medical conditions that place them at high risk,” Dryden-Peterson said. “The benefit for younger individuals and/or fully vaccinated people without considerable medical problems is less certain. Currently Paxlovid is not authorized to be used for low-risk individuals.”

Less than 15 percent of high-risk patients are currently using Paxlovid, he continued.

“Our current priority is to ensure that our vulnerable patients have a plan for this winter,” Dryden-Peterson said. “We recommend COVID and flu vaccination, maintaining a supply of home test kits, understanding if Paxlovid or another option is best for them, and urgently informing their clinic or doctor if they test positive. .”

Travis Andersen can be reached at travis.andersen@globe.com.