Xocova (Ensitrelvir): First Oral COVID-19 PEP Drug by Japan’s Shionogi

Xocova is the first approved oral antiviral for COVID-19 post-exposure prophylaxis in adults and adolescents ages 12 and older.

FDA-approved Xocova (ensitrelvir) brings something new to the COVID-19 drug space. It is the first approved oral antiviral for COVID-19 post-exposure prophylaxis (PEP), giving exposed individuals a pill-based option to help prevent symptomatic disease before it starts.

COVID-19 care has largely focused on two main goals: vaccines to reduce the risk of severe illness and antivirals to treat people who have already started feeling sick.

Xocova introduces a different strategy. The pill is designed for the narrow window immediately after exposure, helping prevent symptomatic disease before it starts.

First: What Is Happening with COVID-19 Today?

COVID-19 activity is relatively quiet right now, but the virus is still very much present. As of June 12, 2026, the CDC said COVID-19 activity was low across most of the country, with very low levels of acute respiratory illness driving people to seek care.

COVID-19 accounted for about 0.09% of emergency department visits for the week ending June 6, 2026.

Even so, COVID-19 continues to carry a measurable toll. During the 2024 to 2025 respiratory virus season, CDC estimates suggest the virus caused about 390,000 to 550,000 hospitalizations and 45,000 to 64,000 deaths in the US.

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The virus is also still changing. FDA advisers recently recommended that 2026 to 2027 COVID-19 vaccines target XFG, a JN.1-lineage variant that made up more than half of US cases in the latest available CDC update. CDC has also noted that future seasonal increases remain possible if variants emerge that are better able to evade prior immunity.

A New Pill-Based Prevention Option After Exposure

Xocova’s five-day pill course is for adults and adolescents ages 12 and older who have been in contact with someone who has COVID-19 but are not yet sick.

While existing COVID-19 antivirals — including Paxlovid, Veklury and Lagevrio — are typically used after a person is diagnosed or develops symptoms, Xocova targets the early window between exposure and symptom onset.

Xocova is not approved in the US to treat active COVID-19.

Developed by Osaka-based Shionogi, a pharmaceutical company with a long-standing portfolio spanning HIV, influenza and bacterial infections, Xocova acts as a main protease inhibitor. This means it blocks an enzyme the virus needs to copy itself, helping slow viral replication before symptoms develop. To be effective, treatment should begin as soon as possible and within 72 hours after contact with someone who has COVID-19.

The FDA approval was based on the Phase III SCORPIO-PEP trial, a global, double-blind, randomized, placebo-controlled study evaluating Xocova as post-exposure prevention. The study enrolled 2,387 participants aged 12 years and older who had a negative local SARS-CoV-2 screening test, had no COVID-19 symptoms at enrollment and had been exposed to a household member with symptomatic COVID-19.

The primary analysis included 2,041 household contacts who also had a centrally confirmed negative SARS-CoV-2 test at baseline. Conducted between June 2023 and September 2024, the trial included participants who largely had some prior immune protection, with more than 99% already carrying antibodies from previous infections, vaccinations or both.

Participants were randomly assigned to receive either Xocova or a placebo within 72 hours after their household member first developed symptoms. By Day 10, Xocova reduced the risk of symptomatic COVID-19 by 67% compared with placebo.

In the Xocova group, 2.9% of participants developed symptomatic COVID-19, compared with 9% in the placebo group.

While national COVID-19 activity is currently low, Xocova’s five-day regimen adds a new preventive option for a virus that continues to place pressure on the healthcare system.

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