Clinical Trial Info

A Study of a Potential Oral Treatment to Prevent COVID-19 in Adults Who Are Exposed to Household Member(s) With a Confirmed Symptomatic COVID-19 Infection

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All participants in the Phase 3 study will receive treatment for COVID-19 as needed, based on their regular doctor's recommendation.

Two-thirds of 2880 participants will also receive two study medicines (PF-07321332 and ritonavir) by mouth twice a day for either five or ten days.

Experiences of people receiving the study medicines to those of the people who do not will be compared.

This will help determine if the study medicines are safe and effective.


Full study data are expected to be released in the coming months and submitted to a peer-reviewed publication.

Pfizer Inc. (NYSE: PFE) on April 29, 2022, shared top-line results from the Phase 2/3 EPIC-PEP (Evaluation of Protease Inhibition for COVID-19 in Post-Exposure Prophylaxis) study evaluating PAXLOVID™ (nirmatrelvir [PF-07321332] tablets and ritonavir tablets) for post-exposure prophylactic use. In this trial, compared to placebo, Pfizer observed risk reductions of 32% and 37% in adults who received PAXLOVID for five and ten days, respectively, to prevent infection. These results, however, were not statistically significant and, as such, the primary endpoint of reducing the risk of confirmed and symptomatic COVID-19 infection in adults who had been exposed to the virus through a household contact was not met.