Pfizer COVID-19 Treatment Pill: What You Need to Know

Illustration of a pill bottle.

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Key Takeaways

  • Pfizer's oral drug to treat COVID-19 is the first of its kind to receive FDA authorization.
  • The treatment, called Paxlovid, is a protease inhibitor, a class of drug used to treat HIV and hepatitis C.
  • The drug could potentially be used against other coronaviruses, in addition to COVID-19.

Pfizer's new oral drug, Paxlovid, is the first COVID-19 pill to receive authorization from the Food and Drug Administration (FDA). Experts say this is a game-changer because people would be able to take the drug at home, possibly eliminating the need to visit a hospital to receive treatment.

Under the emergency use authorization (EUA), Paxlovid will be available via prescription to people 12 and older with confirmed mild-to-moderate COVID-19 who are at high risk of developing a severe case of the disease. A severe case means a patient could become hospitalized, need intensive care, require a ventilator, or even die.

A patient should take the oral drug at the first sign of illness, decreasing their chance of becoming seriously ill with the disease. Pfizer says the drug may be able to reduce burden on hospitals.

“Tackling the COVID-19 pandemic requires both prevention via vaccine and targeted treatment for those who contract the virus," Mikael Dolsten, MD, PhD, Chief Scientific Officer and President of Pfizer said in a statement. "Given the way that SARS-CoV-2 is mutating and the continued global impact of COVID-19, it appears likely that it will be critical to have access to therapeutic options both now and beyond the pandemic."

Who Is At High Risk for Severe COVID-19?

According to the Centers for Disease Control and Prevention (CDC), conditions and factors that may place someone at high risk for severe COVID include, but are not limited to:

  • Cancer
  • Chronic kidney disease
  • Chronic liver disease
  • Chronic lung disease
  • Dementia or other neurological conditions
  • Diabetes
  • Down syndrome
  • Heart conditions
  • HIV
  • Immunocompromised state
  • Mental health conditions
  • Obesity
  • Pregnancy
  • Sickle cell disease
  • Smoking
  • Organ transplant recipient
  • Stroke
  • Substance abuse disorders
  • Tuberculosis

Pfizer's New Oral Drug

The company developed the first U.S. authorized COVID-19 vaccine in partnership with BioNTech. Now they're making strides in COVID-19 treatment.

The company is also developing an antiviral COVID-19 treatment that would be administered intravenously. This option would be available for hospitalized patients.

The Pfizer pill falls into a class of drugs called protease inhibitors, which include oral treatments for pathogens like HIV and hepatitis C.

Data released by the company in December suggests the pill reduces the risk of hospitalization or death by 89% in high-risk adults.


According to the FDA, Paxlovid is administered as three tablets (two tablets of nirmatrelvir and one tablet of ritonavir) taken together orally twice daily for five days. The total regimen consists of 30 tablets, and is not authorized for use beyond five consecutive days. 

How Protease Inhibitors Work

To infect a person’s body, SARS-CoV-2, the virus that causes COVID-19, must penetrate cells of the person's body. Once inside, the virus uses the cells to make copies of its genetic information so it can create more of the virus.

Proteases are enzymes that play an important role in this process. The virus uses this enzyme as a kind of molecular scissor that can chop up long proteins, enabling the virus to replicate itself in the cell. But when proteases are met with molecules called inhibitors, they become blocked and can no longer do their job.

“This is actually essential,” Alejandro Chavez, MD, PhD, assistant professor of pathology and cell biology at Columbia University, tells Verywell. “If it doesn't chop its protein into smaller pieces, the proteins basically don't work.”

Chavez is part of a team of researchers that identified three compounds that could act as inhibitors of the main protease, published in the journal Nature Communications in April. The most important protease to target when combating SARS-CoV-2 is called 3CL. Though the virus contains one other protease, 3CL does most of the heavy lifting when it comes to breaking up proteins.

Paxlovid targets the 3CL protease by introducing new inhibitors into the body. If these molecules can prevent the virus from replicating, the infected person is less likely to become seriously sick.

“Some of these inhibitors against 3CL proteases have been given to animals," Chavez says. "And those animals show rescue from disease—it essentially saved their lives."

What This Means For You

Until now, the only approved treatment against COVID-19 is remdesivir, which only treats those with severe cases of COVID-19 that require hospitalization. Pfizer's oral drug is the first drug available to treat COVID-19 at home.

How Might It Fare Against Variants?

But how will this drug fare against COVID-19 variants?

When developing vaccines, scientists are mindful of how well their vaccines will be able to protect the body against different viral variants. The SARS-CoV-2 virus has mutated to exhibit differences in the spike protein—the part of the virus which helps it latch onto healthy cells.

The oral drug deals with a different component of the virus’s life cycle. By inhibiting the protease, scientists think this antiviral treatment can stop the virus from replicating, regardless of the variation in its spike protein—including Omicron. Protease inhibitor drugs and COVID-19 vaccines, then, will likely support each other in the goal of minimizing how well the virus can infect the body.

“When you hit a virus with three different molecules, each attacking different areas of the virus, then it becomes very challenging for it to solve that problem,” Chavez says.

Additionally, stopping the 3CL protease seems to be effective at preventing viral replication beyond SARS-CoV-2. According to the company statement, the Pfizer drug was “potent” as an in vitro anti-viral agent for multiple coronaviruses, suggesting it may be used against COVID-19 as well as future coronavirus threats.

Though protease inhibitors have proven largely effective in combating pathogens like hepatitis C and HIV, Chavez says there are lessons to be learned from treating those diseases. Over time, viruses may recognize these inhibitors and evolve to become resistant to them. To make protease inhibitor drugs more useful in the long-term, it may be best to take them in combination with other medications, rather than as a stand-alone drug.

The information in this article is current as of the date listed, which means newer information may be available when you read this. For the most recent updates on COVID-19, visit our coronavirus news page.

1 Source
Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.
  1. Iketani S, Forouhar F, Liu H, et al. Lead compounds for the development of SARS-CoV-2 3CL protease inhibitors. Nat Commun. 2021;12(1):2016. doi:10.1038/s41467-021-22362-2

By Claire Bugos
Claire Bugos is a health and science reporter and writer and a 2020 National Association of Science Writers travel fellow.