The FDA Just Authorized Pfizer and Merck Covid Pills for Emergency Use—Here's How Both Work

The FDA Just Authorized Pfizer and Merck Covid Pills for Emergency Use—Here's How Both Work
  • Oops!
    Something went wrong.
    Please try again later.

"Hearst Magazines and Yahoo may earn commission or revenue on some items through the links below."

  • The FDA just authorized both Pfizer and Merck’s antiviral COVID pills for emergency use.

  • Both drugs have been shown to minimize the risk of severe disease in patients with COVID-19—though Pfizer’s drug is almost three times more effective than Merck’s.

  • “This authorization provides a new tool to combat COVID-19 at a crucial time in the pandemic as new variants emerge and promises to make antiviral treatment more accessible to patients who are at high risk for progression to severe COVID-19,” said Patrizia Cavazzoni, M.D., director of the FDA’s Center for Drug Evaluation and Research.

It’s been almost two years since the COVID-19 pandemic began, and treatment options are still limited for people who aren’t experiencing a severe infection. Although monoclonal antibody treatments are gaining in popularity, they’re technically only recommended for those who are considered high-risk for serious complications of the virus. And, most available monoclonal antibody treatments aren’t as effective against the highly contagious Omicron variant.

But not all hope is lost. The Food and Drug Administration (FDA) just authorized the first COVID pills for emergency use. Pfizer’s oral drug, Paxlovid, will be prescribed for use in adults and children ages 12 and up who are at risk of hospitalization or death from COVID-19. Meanwhile Merck’s pill, molnupiravir, which was developed in partnership with Ridgeback Biotherapeutics, has just been cleared by the FDA for at-home use in adults with mild to moderate Covid who are at risk for severe disease.

“Today’s authorization introduces the first treatment for COVID-19 that is in the form of a pill that is taken orally—a major step forward in the fight against this global pandemic,” Patrizia Cavazzoni, M.D., director of the FDA’s Center for Drug Evaluation and Research, said of Pfizer’s approval. “This authorization provides a new tool to combat COVID-19 at a crucial time in the pandemic as new variants emerge and promises to make antiviral treatment more accessible to patients who are at high risk for progression to severe COVID-19.”

But how do these pills work in the first place? And will they be easily accessible to the public? Here’s everything you need to know about COVID pills, according to experts.

What is a “COVID pill,” exactly?

The medications created by Pfizer and Merck are meant to be taken by people who have recently been infected with SARS-CoV-2 and are at a higher risk of progressing to a severe form of COVID-19, which could lead to hospitalization and death. They could work similarly to how Tamiflu does on the flu, says William Schaffner, M.D., an infectious disease specialist and professor at the Vanderbilt University School of Medicine.

How does Pfizer’s COVID pill work?

Each one works slightly differently. Pfizer’s Paxlovid is a protease inhibitor, which keeps viruses from being able to replicate, therefore reducing the amount of them in the body. The medication, which is taken twice daily for five days, is a combination of a molecule developed by Pfizer scientists and ritonavir, a drug commonly used to boost the efficacy of HIV medications. The result “inhibits an enzyme needed for certain viruses to work properly,” explains Jamie Alan, Pharm.D., Ph.D., associate professor of pharmacology and toxicology at Michigan State University.

By slowing down the ability of SARS-CoV-2 to replicate itself, Pfizer’s COVID pill could give your immune system a leg up. The hope is that the “host’s immune defenses will overcome and eliminate it,” explains Martin J. Blaser, M.D., director of the Center for Advanced Biotechnology and Medicine at Rutgers University.

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 consecutive five days. Paxlovid is not authorized for use for longer than five days. Possible side effects include impaired sense of taste, diarrhea, high blood pressure, and muscle aches, as well as potential drug interactions. Check with your doctor if you believe you are eligible to receive Pfizer's COVID-19 pill.

The antiviral pill “should be initiated as soon as possible after diagnosis of Covid-19 and within five days of symptom onset,” according to an FDA statement. Paxlovid is not authorized for the pre-exposure or post-exposure prevention of COVID-19, nor does it serve as a substitute for vaccination. The FDA still urges those eligible to receive a COVID-19 vaccine and booster.

How does Merck’s COVID pill work?

Meanwhile, Merck’s molnupiravir essentially forces the SARS-CoV-2 virus to mutate randomly until it is no longer viable. The drug “inhibits viral replication,” Alan explains, meaning it won’t be able to make you as sick. Merck’s COVID pill is a course of four pills administered twice daily over a period of five days.

How effective are COVID pills?

Alongside other treatment options like monoclonal antibodies—and on top of the lifesaving efficacy of the COVID-19 vaccines—Pfizer’s and Merck’s pills look promising.


In early November, Pfizer released data showing that its COVID pill, administered within three days of infection, can cut hospitalization and death by 89% in non-hospitalized, high-risk adults who had been infected with COVID-19. No patients who took the oral medication died within a month, and fewer than 1% were hospitalized. This is a stark comparison to those who took a placebo—seven died and 7% were hospitalized. A slightly higher percentage of people who started Paxlovid within five days of infection were hospitalized, suggesting that early detection and treatment is preferable.


Merck’s molnupiravir reduced the risk of hospitalization or death from COVID-19 by about 30%: Over the course of a month, nearly 7% of patients who took the medication were hospitalized and one died, compared with 10% of placebo-treated patients who were hospitalized and nine deaths. The FDA did note that Merck’s COVID might not be safe for pregnant women, and will warn against pregnant people taking the medication, according to the New York Times.

Like the Pfizer option, molnupiravir was successful in its clinical trial that an external advisory committee, in consultation with the FDA, recommended that Merck halt its trial early so that more people can benefit from the medication. But with Pfizer’s efficacy almost three times that of Merck’s, there might not be as much of a demand for this option.

Why are COVID pills so important?

Up until this point, there really hasn’t been an easy-to-use medication to treat COVID-19 infections, and Pfizer and Merck can now fill that gap, easing the burden on patients and an already strained healthcare system.

“The aim is to make an oral antiviral for COVID that would be akin to Tamiflu and reduce symptoms, reduce complications, and reduce contagiousness,” says infectious disease expert Amesh A. Adalja, M.D., a senior scholar at the Johns Hopkins Center for Health Security. He calls the idea of a COVID pill “game-changing.”

A treatment like this is definitely needed, Dr. Schaffner says: “At the moment, we’re using monoclonal antibodies, but they’re much more complicated and expensive than giving someone a pill. Monoclonal antibodies have to be given intravenously or through a series of inoculations under your skin,” he explains. “If we had an oral drug that we could give somebody, that would be so much easier.”

This article is accurate as of press time. However, as the COVID-19 pandemic rapidly evolves and the scientific community’s understanding of the novel coronavirus develops, some of the information may have changed since it was last updated. While we aim to keep all of our stories up to date, please visit online resources provided by the CDC, WHO, and your local public health department to stay informed on the latest news. Always talk to your doctor for professional medical advice.

You Might Also Like