After earning multimillion dollar revenues while being an authorised preferred treatment for Covid-19, the US Food and Drug Administration (FDA) has granted a full approval to Pfizer’s oral antiviral Paxlovid (nirmatrelvir + ritonavir). The label is specified for the treatment of “mild-to-moderate Covid-19 in adults who are at high risk for progression to severe COVID-19, including hospitalisation or death.”
This decision makes Paxlovid the first oral antiviral pill, and the fourth drug approved overall, to treat Covid-19 in adults. It follows a March 2023 FDA Advisory Committee meeting where panelists voted 16-1 in favour of the drug’s approval.
The FDA first granted the drug under an emergency use authorisation (EUA) during the pandemic in December 2021. This allowed pharmacists to prescribe the treatment for mild-to-moderate Covid-19 in adults and children ages 12 years and above at high risk for disease progression. Pfizer’s antiviral pill involves a twice-daily three-pill antiviral regimen for five days.
However, upon Paxlovid’s widespread use, some patients reached full recovery from Covid-19 only to test positive again or have a relapse in symptoms within a few days or weeks. This phenomenon was coined Paxlovid rebound. However, other studies found that the relapse in symptoms occurs in patients independent of Paxlovid use. In response to the approval news, some pointed concerns about long-term safety.
Paxlovid’s approval was based on results from the Phase III EPIC-HR clinical trial (NCT04960202). The results demonstrated that, when compared to placebo, Paxlovid significantly reduced the number of participants with Covid-19-related hospitalisations or deaths during 28 days of follow-up. Paxlovid’s most common side effect is diarrhoea.
Since the end of the Covid-19 emergency on 11 May, questions remain surrounding the coverage of Covid-19 drugs such as Paxlovid. Initially, during the pandemic, the Centers for Medicare and Medicaid Services included Paxlovid in a temporary New Covid-19 Treatments Add-On Payment (NCTAP) scheme. However, this scheme also ended on 11 May.
Director for the FDA’s Center for Drug Evaluation and Research, Dr. Patrizia Cavazzoni said, “Today’s approval demonstrates that Paxlovid has met the agency’s rigorous standards for safety and effectiveness, and that it remains an important treatment option for people at high risk for progression to severe COVID-19, including those with prior immunity.”