Pfizer COVID-19 oral antiviral treatment found to reduce patient hospitalization risk by 89%

Nov. 5, 2021

Pfizer Inc. has announced that its investigational novel COVID-19 oral antiviral candidate, PAXLOVID, significantly reduced hospitalization and death, based on an interim analysis of the Phase 2/3 EPIC-HR (Evaluation of Protease Inhibition for COVID-19 in High-Risk Patients).

The randomized, double-blind study involved non-hospitalized adult patients with COVID-19 who are at high risk of progressing to severe illness. The scheduled interim analysis showed an 89% reduction in risk of COVID-19-related hospitalization or death from any cause, as compared to placebo in patients treated within three days of symptom onset (primary endpoint); 0.8% of patients who received PAXLOVID were hospitalized through Day 28 following randomization (3/389 hospitalized with no deaths), compared to 7.0% of patients who received placebo and were hospitalized or died (27/385 hospitalized with 7 subsequent deaths), according to a press release from Pfizer.

The statistical significance of these results was high. Similar reductions in COVID-19-related hospitalization or death were observed in patients treated within five days of symptom onset; 1.0% of patients who received PAXLOVID were hospitalized through Day 28 following randomization (6/607 hospitalized, with no deaths). This had been compared to 6.7% of patients who received a placebo (41/612 hospitalized with 10 subsequent deaths), with high statistical significance.

In the overall study population through Day 28, no deaths were reported in patients who received PAXLOVID. By contrast, 10 (1.6%) deaths in patients who received placebo.

At the recommendation of an independent Data Monitoring Committee and in consultation with the U.S. Food and Drug Administration (FDA), Pfizer will cease further enrollment into the study due to the overwhelming efficacy demonstrated in these results and plans to submit the data as part of its ongoing rolling submission to the U.S. FDA for Emergency Use Authorization (EUA) as soon as possible.

If approved, PAXLOVID, which originated in Pfizer’s laboratories, would be the first oral antiviral of its kind -- a specifically designed SARS-CoV-2-3CL protease inhibitor. Upon successful completion of the EPIC clinical development program and subject to approval or authorization, it could be prescribed more broadly as an at-home treatment to help reduce illness severity, hospitalizations, and deaths. Treatment may also reduce the probability of infection following exposure, among adults. It has demonstrated potent antiviral in-vitro activity against circulating variants of concern, as well as other known coronaviruses. This suggests it may have potential as a therapeutic for multiple types of coronavirus infections.

Pfizer press release

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