Recently, Pfizer announced its investigational novel COVID-19 oral antiviral candidate, PAXLOVID, which was found to significantly reduce hospitalization and death, based on interim analysis of the Phase 2/3 EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients). EPIC-HR was a randomized, double-blind study of non-hospitalized adult patients with COVID-19, who were at high risk of progressing to severe illness.1 The analysis showed an 89% reduction in risk of COVID-19-related hospitalization or death from any cause compared to placebo in patients treated within three days of symptom onset.1
The data were collected from more than 1,200 people with COVID-19 who were at high risk of progressing to severe illness. PAXLOVID works by inhibiting an enzyme known as the main protease (Mpro) that plays a role in coronavirus replication. This is combined with ritonavir, which is an HIV drug, that helps to slow the breakdown of the protease inhibitor.2
Through Day 28 of the study, no deaths were reported in patients who received PAXLOVID, compared to ten deaths in patients who received a placebo. This antiviral pill is the second of its kind to demonstrate efficacy against COVID-19, and appears to be more effective than a similar offering from Merck.3 Both the Pfizer and the Merck pills target high-risk patients, such as those above the age of 60 or those with comorbidities like obesity.
If approved or authorized, PAXLOVID would be the first oral antiviral of its kind, specifically designed as a SARS-CoV-2-3CL protease inhibitor. It could potentially be prescribed broadly as an at-home treatment to help reduce illness severity, hospitalizations and deaths. PAXLOVID has also been shown to demonstrate potent antiviral in vitro activity against circulating variants of concerns, as well as other known coronaviruses. This Pfizer drug was designed to be a five-day regimen that is designed to block the virus from making copies of itself, The US government is currently in the process of procuring 1.7 million treatment courses from Pfizer, with an additional option to purchase 3.3 million more. Pfizer has begun manufacturing its drug and projects producing more than 180,000 pill packs, each containing a single treatment course by the end of this year. The goal is to rapidly scale up manufacturing to at least 21 million packs in the first half of next year with a total production of 50 million packs in 2022.4 Pfizer is also conducting studies of PAXLOVID in lower-risk patients.4
- Pfizer’s novel covid-19 oral antiviral treatment candidate reduced risk of hospitalization or death by 89% in interim analysis of phase 2/3 epic-HR study. Pfizer. (2021, November 5). Retrieved November 10, 2021, from https://www.pfizer.com/news/press-release/press-release-detail/pfizers-novel-covid-19-oral-antiviral-treatment-candidate.
- Graham, F. (2021, November 8). Daily briefing: Pfizer’s Covid Pill looks promising. Nature News. Retrieved November 10, 2021, from https://www.nature.com/articles/d41586-021-03379-5.
- Robbins, R. (2021, November 10). Covid updates: Pfizer says its antiviral pill is highly effective. The New York Times. Retrieved November 10, 2021, from https://www.nytimes.com/live/2021/11/05/world/covid-delta-variant-vaccine.
- Johnson, C. Y. (2021, November 5). Antiviral pills from Pfizer, Merck, show promise against worst covid-19 outcomes. The Washington Post. Retrieved November 10, 2021, from https://www.washingtonpost.com/health/2021/11/05/pfizer-covid-pill/.