Pfizer’s COVID Pill Paxlovid Inching Closer to Getting FDA Approval

A box of Paxlovid, Pfizer's COVID-19 pill, is seen in a file image. (Jennifer Lorenzini/Reuters)

An advisory committee from the U.S. Food and Drug Administration (FDA) has voted in favor of approving a new drug application for Pfizer’s COVID pill Paxlovid, even as potential drug interaction risks were highlighted during the committee meeting.

Paxlovid is an oral antiviral pill that has been available for use in the United States since Dec. 22, 2021, under Emergency Use Authorization (EUA). In June 2022, Pfizer submitted an application for full FDA approval of the drug. On March 16, the FDA’s Antimicrobial Drug Advisory Committee (AMDAC) met to give its opinion on the issue.

The committee voted in support of approving Paxlovid.

Committee members were specifically answering the following question: “Is the overall benefit-risk assessment favorable for Paxlovid when used for the treatment of mild-to-moderate COVID-19 in adults who are at high risk for progression to severe COVID-19, including hospitalization or death?”

Sixteen members voted “yes,” with only one voting “no.”

Even though AMDAC voted in favor of approving Paxlovid, the FDA is not obliged to follow its recommendation, but the agency usually follows the committee’s advice. The FDA is scheduled to make a final decision on the matter in May, CNBC reported.

The drug was shown to reduce the chances of hospitalization or death among high-risk adults by 60 to 85 percent regardless of vaccination or infection history.

An FDA presentation (pdf) during the AMDAC meeting raised concerns about adverse effects resulting from drug-drug interactions (DDI). DDI refers to a change in how a drug affects the body when another drug is taken together with it.

More than 50 percent of Paxlovid-eligible Medicare and Veterans Administration patients are on medication with Paxlovid DDIs, it pointed out.

“Serious adverse events due to labeled Paxlovid DDIs have been reported, including deaths,” the report states.

The FDA reported 271 serious adverse events potentially related to Paxlovid DDIs, which included 147 hospitalizations and six deaths.

The presentation suggested that on a population level, the “benefit of Paxlovid use outweighs risk” and that using the drug could result in about 1,500 saved lives and the prevention of 13,000 hospitalizations each week.

However, on an individual level, the FDA stated that the “benefit of Paxlovid will not outweigh risk in all high-risk patients, particularly if DDIs are not adequately managed.”

Paxlovid Treatment Impact, Adverse Events

One Paxlovid trial looked at high-risk adults who had no prior COVID-19 infection and were not vaccinated. Paxlovid use was found to reduce hospitalization or death by 86 percent in the group that received treatment within five days of symptom onset.

Among healthy adults without comorbidities, an FDA review of Pfizer data showed Paxlovid made no meaningful difference, regardless of whether the individuals were vaccinated.

According to the FDA presentation, Paxlovid demonstrated an “overall favorable safety profile” in clinical trials. Most of the observed adverse events resulting from Paxlovid use were “either mild or moderate in severity.”

The most common adverse events were found to be dysgeusia (taste disorder) and diarrhea, both of which occurred at a higher frequency among Paxlovid users.

During the EUA period, Paxlovid was found to be linked with adverse events like headaches, hypertension, abdominal pain, anaphylaxis, malaise, vomiting, and nausea by Pfizer or the Office of Surveillance and Epidemiology.

Low Benefit for Younger Adults

An Israeli study from August 2022 published in the New England Journal of Medicine found that Paxlovid appeared to provide little to no benefit for individuals between 40 and 64 years of age.

Among the 66,433 patients who were between 40 and 64 years old, hospitalization due to COVID-19 occurred in 7 treated patients at a rate of 15.2 cases per 100,000 person-days. Among untreated patients, hospitalizations occurred in 327 individuals at a rate of 15.8 cases per 100,000 person-days, showing no significant difference.

The high cost of Paxlovid has also come under the spotlight.

On Jan. 10, China’s National Healthcare Security Administration (NHSA) announced that Paxlovid will not be included in its national reimbursement plan due to the high cost of the drug.

The U.S. government has purchased 23.7 million courses of the drug for about $530 per course, and the government is supplying the drug to patients for free.

According to data from the Administration for Strategic Preparedness and Response, part of the Department of Health and Human Services, 12.7 million courses of Paxlovid have been delivered in the United States between Dec. 17, 2021, and March 12, 2023.

In total, 8.5 million courses have been administered.

Katabella Roberts contributed to this report.