Shionogi Launches XOCOVA® in the United States as the First Oral Post-Exposure COVID-19 Prevention Therapy
Shionogi Inc., the U.S. subsidiary of Japan-based pharmaceutical company Shionogi & Co., Ltd., has announced the commercial availability of XOCOVA® (ensitrelvir) in the United States following its approval for post-exposure prophylaxis (PEP) of COVID-19. The oral antiviral is authorized for use in adults and adolescents aged 12 years and older who have recently been exposed to someone infected with COVID-19, providing a new preventive treatment option designed to reduce the likelihood of developing the disease after exposure.
The launch marks a significant milestone in COVID-19 management by introducing the first oral antiviral therapy specifically approved in the United States for preventing infection after known exposure. Unlike treatments that are initiated only after symptoms appear, XOCOVA is intended to interrupt viral replication during the critical period between exposure and the onset of illness, potentially reducing disease progression before symptoms develop.
Expanding the COVID-19 Prevention Toolbox
Although vaccination remains the cornerstone of COVID-19 prevention, breakthrough infections and recurring seasonal waves continue to create challenges for healthcare systems and vulnerable populations. Individuals who live with infected family members, caregivers, healthcare workers, and those in communal settings remain at increased risk of contracting the virus following close contact.
The availability of XOCOVA introduces a new strategy aimed at reducing infection risk immediately after exposure. By acting during the earliest stages of viral replication, the therapy provides healthcare professionals with an additional option to help patients who may be at heightened risk of developing COVID-19.
Shionogi stated that the treatment should be initiated as soon as possible and within 72 hours of exposure to an individual confirmed to have COVID-19, maximizing its ability to prevent viral replication before symptoms emerge.
How XOCOVA Works
XOCOVA contains ensitrelvir, an oral antiviral agent designed to inhibit SARS-CoV-2 replication.
Rather than targeting symptoms, the medication works directly against the virus by blocking a key enzyme required for viral reproduction. Preventing the virus from multiplying during the earliest stages after exposure may reduce the likelihood that infection becomes established.
This mechanism distinguishes post-exposure prophylaxis from traditional antiviral treatment approaches, which typically begin only after infection has been confirmed or symptoms have already appeared.
By intervening earlier, healthcare providers hope to reduce both disease burden and potential transmission.
Convenient Five-Day Oral Regimen
The treatment regimen has been designed for ease of administration.
Patients begin therapy with:
- Three 125 mg tablets (375 mg total) taken together on Day 1.
This loading dose is followed by:
- One 125 mg tablet once daily on Days 2 through 5.
Because treatment effectiveness depends on early intervention, patients are encouraged to begin therapy promptly after a confirmed exposure.
Healthcare professionals recommend that individuals who may benefit from XOCOVA become familiar with the dosing instructions in advance so treatment can begin without delay if exposure occurs.
Physicians Highlight the Importance of Early Action
Medical experts believe the availability of an oral post-exposure option could help improve preparedness, particularly during periods of rising COVID-19 activity.
Dr. Charles Vega, Health Sciences Clinical Professor at the University of California, Irvine School of Medicine, emphasized that XOCOVA offers clinicians an entirely new preventive strategy following known exposure.
According to Dr. Vega, initiating treatment during the brief period between exposure and symptom onset provides a logical opportunity to reduce the risk of illness, particularly among older adults and individuals with underlying health conditions who may face greater risk of severe disease.
He noted that conversations about COVID-19 prevention will increasingly include not only vaccination recommendations but also education regarding rapid access to post-exposure therapy should exposure occur.
Addressing Seasonal COVID-19 Surges
The commercial launch comes as public health experts continue monitoring seasonal increases in COVID-19 transmission.
Since 2020, the United States has experienced recurring summer increases in COVID-19 cases.
Wastewater surveillance conducted by Biobot Analytics has recently indicated rising concentrations of SARS-CoV-2, suggesting another seasonal increase may be developing.
At the same time, forecasting models from the U.S. Centers for Disease Control and Prevention indicate that certain regions, particularly the South and West, could experience elevated COVID-19 activity after relatively mild transmission during the previous fall and winter.
The timing of XOCOVA’s availability therefore aligns with public health efforts aimed at improving preparedness before seasonal transmission accelerates.
Applying the Concept of Post-Exposure Prophylaxis
Post-exposure prophylaxis has long been used successfully for other infectious diseases.
Healthcare providers routinely prescribe preventive medications following exposure to influenza, HIV, hepatitis, and certain bacterial infections.
Dr. David Wohl, Professor of Medicine at the University of North Carolina School of Medicine, explained that applying this strategy to COVID-19 represents an important evolution in disease prevention.
He noted that having an oral medication available for immediate use following confirmed exposure gives patients an opportunity to act before illness develops.
Because the treatment window is limited to 72 hours following exposure, Dr. Wohl emphasized the value of having the medication readily available when appropriate so therapy can begin quickly.
Preparing Patients Before Exposure Occurs
Healthcare professionals encourage patients who may qualify for XOCOVA to understand how the medication should be used before an exposure takes place.
Patients should:
- Review dosing instructions.
- Check medication expiration dates.
- Discuss current medications with healthcare providers.
- Review potential interactions with prescription and over-the-counter medicines.
- Inform providers about vitamins or dietary supplements.
- Confirm they are not pregnant or breastfeeding before starting therapy.
Advance planning can help eliminate delays during the narrow treatment window when effectiveness is greatest.
Nationwide Pharmacy Availability
To support broad access, Shionogi has partnered with national and regional pharmacy networks throughout the United States.
The company indicated that selected retail pharmacies will maintain inventory of XOCOVA, while pharmacies that do not routinely stock the medication will be able to obtain supplies through Shionogi’s wholesale distribution network.
This distribution strategy is intended to ensure that eligible patients can access therapy rapidly after exposure regardless of geographic location.
Patient Assistance and Affordability
Recognizing the importance of reducing financial barriers to treatment, Shionogi has introduced a commercial co-pay assistance program for eligible patients.
Under the program, commercially insured individuals who meet eligibility requirements may pay as little as $0 per prescription.
The initiative is designed to improve accessibility while encouraging appropriate use among patients who may benefit from post-exposure prophylaxis.
U.S.-Based Manufacturing and Supply Chain
Shionogi also highlighted its domestic manufacturing capabilities supporting XOCOVA.
According to the company, every major component of the product is produced within the United States, including:
- Active pharmaceutical ingredient manufacturing
- Drug formulation
- Packaging
- Quality control testing
- Product release testing
- Supply chain management
- Distribution
Domestic production is expected to strengthen supply reliability while supporting timely product availability nationwide.
COVID-19 Continues to Present a Public Health Challenge
Although vaccination campaigns and previous infections have reduced overall disease severity for many individuals, COVID-19 continues to circulate widely.
Current variants derived from the Omicron lineage remain highly transmissible, particularly within households and other close-contact environments.
Studies suggest that nearly half of individuals living with an infected household member may eventually develop COVID-19 following exposure.
CDC estimates indicate that between October 2025 and July 2026, the United States experienced:
- Between 4.2 million and 12.7 million new COVID-19 cases
- Approximately 840,000 to 2.3 million outpatient medical visits
- Between 130,000 and 250,000 hospitalizations
- Approximately 14,000 to 42,000 deaths
These figures illustrate that COVID-19 continues to impose a substantial healthcare burden despite advances in vaccination and antiviral therapies.
Long-Term Health Consequences Remain a Concern
Beyond acute infection, researchers continue to study the long-term effects associated with COVID-19.
Growing evidence indicates that infection may contribute to increased risks of several chronic health conditions during the months following recovery.
Reported complications include:
- Neurological disorders
- Cardiovascular disease
- Respiratory complications
- Chronic kidney disease
- Persistent fatigue
- Long COVID symptoms
Older adults and individuals residing in long-term care facilities remain particularly vulnerable to severe outcomes and complications.
Reducing infections through vaccination, preventive measures, and early interventions such as post-exposure prophylaxis may therefore provide benefits extending beyond prevention of acute illness alone.
Supporting a Comprehensive Prevention Strategy
The introduction of XOCOVA reflects an evolving approach to COVID-19 prevention that combines vaccination, early diagnosis, antiviral therapy, and post-exposure intervention.
While vaccines remain the primary defense against severe disease, healthcare providers increasingly recognize the value of additional preventive options for individuals who experience known exposure or face elevated risk due to age, underlying medical conditions, or frequent contact with infected individuals.
By offering the first oral antiviral specifically approved for post-exposure prophylaxis, Shionogi aims to provide patients and clinicians with a timely tool that can be deployed during the narrow window between exposure and symptom onset. As COVID-19 continues to circulate and seasonal waves remain a reality, XOCOVA has the potential to become an important component of comprehensive disease prevention strategies, helping reduce illness, lessen healthcare utilization, and improve preparedness for future outbreaks.
About SCORPIO-PEP
The global, double-blind, randomized, placebo-controlled Phase 3 study, SCORPIO-PEP, assessed the safety and efficacy of XOCOVA as post-exposure prophylaxis for COVID-19. The study was conducted from June 2023–September 2024. It included 2,387 study participants aged 12 years and older with a negative local screening test for SARS-CoV-2 infection and no symptoms at the time of enrollment, who were exposed to a person living in their household with symptomatic COVID-19. The primary analysis included 2,041 household contact participants with a central laboratory-confirmed negative SARS-CoV-2 test at baseline.
More than 98% of household contacts tested positive for antibodies against SARS-CoV-2 N (nucleocapsid) or S (spike) proteins, indicating that nearly all had evidence of previous SARS-CoV-2 infection or vaccination, or both.20
Study participants were randomly assigned at a 1:1 ratio to receive XOCOVA (375 mg on Day 1 and 125 mg on Days 2-5) or placebo, once daily, and began treatment within 72 hours of when the household member with COVID-19 began showing symptoms. Participants then continued XOCOVA (125 mg) or placebo for five days.
In the primary analysis population, XOCOVA significantly reduced the risk of symptomatic COVID-19 by 67% in individuals following exposure to an infected individual through Day 10 compared with placebo (ensitrelvir n=1,030; placebo n=1,011).2 The most common adverse events (regardless of causality) occurring in greater than or equal to 1% of the XOCOVA group and at a greater frequency compared to placebo were headache, diarrhea, and cough.1 There were no reports of altered taste (dysgeusia) attributed to XOCOVA in the trial.2,20
Results from the SCORPIO-PEP trial were published in the New England Journal of Medicineon May 14, 2026. SCORPIO-PEP is the first and only Phase 3 study of an oral antiviral to meet the primary endpoint of preventing COVID-19 following exposure to an infected individual.
About XOCOVA
XOCOVA® (ensitrelvir) is a SARS-CoV-2 main protease inhibitor created through joint research between Hokkaido University and Shionogi. SARS-CoV-2 has an enzyme called the main protease, which is essential for the replication of the virus. XOCOVA suppresses the replication of SARS-CoV-2 by selectively inhibiting the main protease.
XOCOVA is approved in the U.S. and Japan for post-exposure prophylaxis of COVID‑19 in adults and adolescents 12 years of age and older following contact with an individual who has COVID-19.
XOCOVA received emergency regulatory approval in Japan in November 2022 and full approval in March 2024 for the treatment of COVID-19 in adults and adolescents 12 years of age and older based on results from SCORPIO-SR, a Phase 3 study conducted in Asia during the Omicron-dominant phase of the pandemic. Results from this study were published in JAMA Network Open. XOCOVA received supplemental approval in June 2026 in Japan for pediatric patients aged 6 to under 12 years who weigh at least 20 kg for the treatment of COVID-19.