Are your patients at increased risk of severe illness from COVID-19? 

We are investigating ibuzatrelvir, an oral antiviral, in high risk adult and adolescent patients with COVID-19. 

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 hospitalisation and death for patients at higher risk of severe disease,1 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 oral ibuzatrelvir compared with placebo in non-hospitalised, 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: 

Participant eligibility

This clinical trial is enrolling non-hospitalised 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 or willing 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 randomised 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 in the study 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. 

Together, we can make a difference.

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.   

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 hospitalisation 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.

Do you have patients with COVID-19 in your care?

To learn more about Pfizer’s Antiviral COVID-19 Clinical Trials and how to refer potentially eligible patients, please complete the contact form and a member of the Pfizer team will contact you.  

Contact Form

Thank you for considering Pfizer’s Antiviral COVID-19 Clinical Trials for your patients. 

Site finder

Find an ASPIRE-HR study site near you 

The ASPIRE-HR clinical trial is taking place in multiple countries worldwide. 

To find your nearest study site, please enter your postal code and select the optimal distance to view on the map from the drop-down menu: 

      References

      1. Centres for Disease Control and Prevention. COVID-19 Treatment Clinical Care for Outpatients. CDC. Published 20 December 2024. Accessed 28 March 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 Hospitalised. ClinicalTrials.gov identifier: NCT05799495. Updated 9 October 2024. Accessed 6 March 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 14 August 2023. Accessed 13 March 2025.

      https://clinicaltrials.gov/study/NCT05011513

      4. EPIC-HR: Study of Oral PF-07321332/​Ritonavir Compared With Placebo in Non-hospitalised High Risk Adults With COVID-19. ClinicalTrials.gov identifier: NCT04960202: Updated 09 February 2023. Accessed 13 March 2025.

      https://clinicaltrials.gov/study/NCT04960202