For many, a COVID-19 diagnosis can still have a significant impact on their daily lives and well-being.
While clinical trials have shown that some COVID-19 treatments have demonstrated a reduction in the risk of hospitalization and death for patients at higher risk of severe disease1, there remains a need for additional COVID-19 treatment options that do not require administration in a healthcare setting, are not limited by drug interactions, and can be taken by people who may not be candidates for other treatments.
Pfizer ASPIRE-HR is a phase 3 clinical trial evaluating orally administered ibuzatrelvir.
This clinical trial will assess the safety, efficacy, and tolerability of ibuzatrelvir compared with placebo in non-hospitalized, symptomatic adult and adolescent participants with COVID-19 who are at high risk of progressing to severe illness.
Ibuzatrelvir has the potential to be a COVID-19 treatment for patients with limited treatment options, if the clinical trial is successful and the investigational medicine is approved by regulators.
Watch this video to learn more about ibuzatrelvir and the ASPIRE-HR clinical trial:
This clinical trial is enrolling non-hospitalized participants who:
Are adults (18+) or adolescents (12+)
Have COVID-19 and developed signs or symptoms within the last 5 days
Have risk factors for severe illness or complications from COVID-19, including:
- BMI ≥30 kg/m2
- Current smoker
- Chronic lung disease
- Asthma requiring daily prescribed therapy
- Cardiovascular disease
- Type 1 or Type 2 diabetes
- Mild to moderate renal impairment
- Neurodevelopmental disorders
- Sickle cell disease
- Moderate immunosuppression
May not be able to take currently approved treatments for COVID-19
Have not received a COVID-19 vaccine in the last 4 months
Additional requirements apply. Only Principal Investigators can determine eligibility.
About the clinical trial
Eligible participants will be randomized 1:1 to receive oral ibuzatrelvir or placebo twice daily for 5 days (10 total doses). Participants may also receive permitted standard-of-care treatments for COVID-19.
Participants will be enrolled for approximately 24 weeks, including screening, treatment, and follow-up. Participants will need to attend at least 12 appointments, some of which may be conducted via telemedicine.
There is no cost to participate, and health insurance is not required. Participants will receive compensation for completing clinical trial activities.
Ibuzatrelvir mechanism of action
Ibuzatrelvir is a selective inhibitor of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro), a virally encoded enzyme that is critical to the SARS-CoV-2 replication cycle.
In earlier clinical trials, ibuzatrelvir was observed to reduce SARS-CoV-2 viral RNA levels in patients with COVID-19 through inhibition of viral replication.2 Prior studies demonstrate that inhibition of viral replication has the potential to correlate with positive clinical outcomes including prevention of disease progression and decreased rates of hospitalization and death.3, 4
Additionally, we are researching whether ibuzatrelvir’s lower potential for drug-drug interactions may benefit patients who take other medications for overlapping health conditions.
Ibuzatrelvir is investigational and has not been approved by any health authority.
Get started
Answer a 2-minute questionnaire and speak to a study representative.
A first step as you consider connecting with a Principal Investigator is to answer a 2-minute online questionnaire about your interest and willingness to be contacted. If your answers show the study might be a good fit for you and your patient, you may choose to have your contact information shared with a study clinic that you select for further discussion.
Get connected.
Your answers to these questions will only be linked to you if your responses indicate that you would like to be connected with a Principal Investigator and you choose to share your contact information with the study clinic. Pfizer study team members and our partners will have access to reports containing aggregated data that will not be directly linked back to you. Only the study staff can determine if your patient meets the study’s eligibility criteria and is able to enroll in the study.
People are often introduced to clinical trials through conversations with their healthcare providers. We appreciate you taking the time to have discussions with your patients and their loved ones who may be interested in contributing to research.
Should any of your patients take part in this clinical trial, they will have the option to remain under your medical care for all non-study-related needs.
Thank you for considering your patients for this important clinical trial.
1. Centers for Disease Control and Prevention. COVID-19 Treatment Clinical Care for Outpatients. CDC. Published December 20, 2024. Accessed March 28, 2025. https://www.cdc.gov/covid/hcp/clinical-care/outpatient-treatment.html
2. A Study to Understand the Effect and Safety of the Study Medicine PF-07817883 in Adults Who Have Symptoms of COVID-19 But Are Not Hospitalized. ClinicalTrials.gov identifier: NCT05799495. Updated October 9, 2024. Accessed March 6, 2025. https://clinicaltrials.gov/study/NCT05799495
3. Evaluation of Protease Inhibition for COVID-19 in Standard-Risk Patients (EPIC-SR). ClinicalTrials.gov identifier: NCT05011513. Updated August 14, 2023. Accessed March 13, 2025. https://clinicaltrials.gov/study/NCT05011513
4. EPIC-HR: Study of Oral PF-07321332/Ritonavir Compared With Placebo in Nonhospitalized High Risk Adults With COVID-19. ClinicalTrials.gov identifier: NCT04960202. Updated February 9, 2023. Accessed March 13, 2025. https://clinicaltrials.gov/study/NCT04960202