PfizerPfizer Inc. (NYSE: PFE) 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.

Available safety data for PAXLOVID has been generally consistent in more than 3,500 PAXLOVID-treated participants across the EPIC-HR, EPIC-SR and EPIC-PEP studies, as well as in reported post-market safety experience. In EPIC-PEP, this safety profile remained generally consistent when PAXLOVID was used for either five or ten days. Analyses of all secondary endpoints and sub-groups are ongoing, and results will be included in the publication or presentation of the final study results.

"We designed the clinical development program for PAXLOVID to be comprehensive and ambitious with the aim of being able to help combat COVID-19 in a very broad population of patients," said Albert Bourla, Chairman and Chief Executive Officer, Pfizer. "While we are disappointed in the outcome of this particular study, these results do not impact the strong efficacy and safety data we've observed in our earlier trial for the treatment of COVID-19 patients at high risk of developing severe illness, and we are pleased to see the growing global use of PAXLOVID in that population."

PAXLOVID is currently approved or authorized for conditional or emergency use in more than 60 countries across the globe to treat high-risk COVID-19 patients.

Please see Full Emergency Use Authorization (EUA) Prescribing Information available at and

About the Phase 2/3 EPIC-PEP Study

The top-line analysis evaluated data from 2,957 adults. Enrolled adults had a negative SARS-CoV-2 rapid antigen test result and were asymptomatic household contacts with exposure within 96 hours to an individual who was symptomatic and recently tested positive for SARS-CoV-2. Each patient was randomized (1:1:1) to receive orally twice daily one of the following: (i) PAXLOVID for five days followed by placebo for 5 days, (ii) PAXLOVID for ten days or (iii) placebo for ten days.

Recruitment began in September 2021 and was completed during the peak of the COVID-19 Omicron wave.

Additional details on the study are available on

(NCT05047601). Full study data are expected to be released in the coming months and submitted to a peer-reviewed publication.

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