The Food and Drug Administration on Thursday granted full approval to Pfizer’s Covid antiviral pill, Paxlovid, for adults at high risk of becoming seriously ill with the virus.
Paxlovid is specifically recommended for the treatment of mild to moderate Covid in adults over 50 and people with certain medical conditions which put them at higher risk of ending up in hospital or dying from Covid.
This includes those with diabetes, heart disease, cancer, or a weakened immune system.
As much as three quarters of adults in the United States are at high risk for severe Covid.
The FDA first made Paxlovid available in December 2021 under emergency use authorization for high-risk people aged 12 and over. Under this designation, the FDA quickly approved the treatment based on preliminary clinical trial data.
The latest FDA decision means that there is now ample clinical data indicating that Paxlovid is safe and effective.
The treatment consists of two drugs: nirmatrelvir, which blocks a key enzyme the Covid virus needs to replicate, and ritonavir, which boosts the first drug’s ability to fight infection.
Pfizer and the FDA see the treatment as an important complementary tool to vaccination that can help high-risk Americans manage their Covid infections and ultimately save lives.
FDA researchers estimated, based on Covid rates in January, that Paxlovid could ‘lead to 1,500 lives saved and 13,000 hospitalizations averted each week’ in the US
But it’s unclear what adoption will look like later this year.
The United States has 1.1 million treatment courses available free nationwide. Once this period has elapsed, the government will shift the distribution of Paxlovid to the commercial market.
This means Pfizer will sell Paxlovid directly to healthcare providers at a price the company has not disclosed. Paxlovid currently costs around $530 per course.
Pfizer, which saw Paxlovid sales soar to nearly $19 billion in 2022, expects the drug’s revenue to drop 58% in 2023.
In March, an independent panel of FDA advisers recommended the treatment based on three of Pfizer’s clinical trials.
One trial looked at high-risk adults who weren’t vaccinated and had never been infected with Covid.
This trial found that Paxlovid reduced the risk of hospitalization or death by 86% in adults treated within five days of their first symptoms, and by 89% in those treated within three days, according to an FDA review of company data.
No major safety issues were identified in the trial, according to the review, although the agency flagged 137 drugs that could cause serious side effects if they interacted with Paxlovid.
The FDA said the most common drugs with safety concerns were immunosuppressants, which are often used to treat HIV and organ transplant patients.
The FDA’s Office of Surveillance and Epidemiology recorded 271 reports of serious adverse events potentially related to drug interactions with Paxlovid, including 147 hospitalizations and six deaths, as of late January.
FDA staff said these events could potentially be prevented by adjusting the dose of certain drugs, increasing patient monitoring, and ensuring that product labeling informs prescribers and patients of potential drug interactions.
Another area of concern for some doctors is the “rebound case” of Paxlovid. This is when patients undergoing treatment see their Covid symptoms return or test positive soon after their initial recovery.
Reports of these cases appeared shortly after Paxlovid entered the market.
President Joe Biden and his former chief medical adviser, Dr Anthony Fauci, apparently recovered from Covid after taking the antiviral cocktail, but tested positive again shortly after recovering.
An FDA review of Pfizer clinical trials found that overall rebound rates ranged from 10% to 16%, “with no evidence of a higher rate of symptom rebound or moderate symptom rebound” in patients with received Paxlovid compared to patients who received a placebo.
These findings also hold regardless of patients’ risk of severe disease, or whether the omicron variant or an earlier strain of the virus was dominant, according to the FDA review.