COVID Antivirals Fight Omicron Better Than Monoclonal Antibodies

A bottle of molnupiravir on a teal background.


Key Takeaways

  • Antiviral drugs seem to be effective treatments against the Omicron variant of COVID.
  • Monoclonal antibody treatments that were used against the earlier COVID variants are no longer effective.
  • Two antiviral drugs—Paxlovid and molnupiravir—can be taken by mouth. However, they are only effective if taken within five days of the onset of symptoms.
  • People should test for COVID as soon as possible and tell their healthcare provider if they test positive.

As the virus that causes COVID-19 continues to change, the effectiveness of treatments is changing, too.

The Omicron variant does not respond to some of the treatments that were used on earlier variants of COVID-19, like monoclonal antibodies.

The goods news is that there are two oral antiviral drugs that appear to work well. And it’s getting easier to access them.

Antivirals Are Effective Against Omicron

There are two antiviral pills used to treat people with confirmed mild-to-moderate COVID-19 who are at risk of severe illness:

  • A combination of nirmatrelvir and ritonavir (made by Pfizer and sold under the brand name Paxlovid)
  • Molnupiravir (made by Merck and sold under the brand name Lagevrio)

Both pills require a prescription.

Mirella Salvatore, MD, an infectious disease specialist and assistant professor of medicine at Weill Medical College of Cornell University in Manhattan, told Verywell that the antiviral drugs were made to block certain mechanisms within the virus that don’t change from variant to variant.

That’s one reason why antivirals are still working against Omicron while other treatments aren’t.

That said, antiviral treatment has a specific goal: It’s meant to help keep at-risk people from getting seriously ill if they catch COVID. It will not necessarily prevent a person from getting sick if they are around someone with the virus.

For example, early results from Pfizer’s ongoing clinical trials for Paxlovid showed the drug does not appear to help prevent people from getting COVID if they’ve been exposed.

Still, for at-risk people who do get COVID, antivirals are a key—potentially life-saving—treatment.

COVID “Relapse” After Paxlovid

While it appears to be rare, there are reports of COVID patients who took Paxlovid “relapsing” after completing treatment.

Researchers are still trying to figure out why relapse happens, but it might be that for these patients, one round of the pills isn’t enough to clear the virus.

Pfizer’s CEO said that if COVID symptoms return after finishing the treatment, patients should ask their provider to prescribe more of the medication.

However, that might not be possible until the FDA issues guidance about treating COVID patients who relapse.

Potential Drug Interactions

While antivirals are an important tool for preventing COVID patients from getting very sick, there are some considerations that providers and patients need to talk about before using them.

Jeff Pearson, PharmD, a clinical pharmacy specialist in infectious diseases at Brigham and Women’s Hospital in Boston, told Verywell that while Paxlovid is effective, it can interact with a long list of medications that patients might be taking.

According to Pearson, it’s crucial that providers and pharmacists review all the medications a patient is taking before prescribing Paxlovid.

For many of the drugs that interact with Paxlovid, Pearson said a patient might be able to stop taking them just for the five days they need to take the antiviral.

Salvatore said that while some medications can safely be stopped during Paxlovid treatment, others—like cancer drugs or heart medications—should not be discontinued.

Most Monoclonal Antibodies Don’t Treat Omicron

If antivirals are not effective or are not available, the National Institutes of Health (NIH) recommends monoclonal antibodies as the next step in COVID treatment.

Monoclonal antibody treatments are given through a vein (intravenously) and are intended for people with mild-to-moderate COVID-19 who are at high risk of severe illness. Another antiviral drug, remdesivir, is also given intravenously.

Monoclonal antibody therapies are not very effective against Omicron. According to Salvatore, the changes in the COVID virus variants have made some monoclonal antibody treatments ineffective.

According to the NIH’s COVID-19 Treatment Guidelines, the following are no longer recommended to treat COVID because they are ineffective against Omicron:

  • Bamlanivimab plus etesevimab from Lilly
  • Casirivimab plus imdevimab from Regeneron
  • Sotrovimab from GSK

The NIH also does not recommend that any of these treatments be used to try to prevent a person from getting COVID after they’ve been exposed (post-exposure prophylaxis).

In terms of treating people who are already sick, Pearson said that “sotrovimab had good activity against the original BA.1 Omicron variant,” but that it was not as effective against BA.2, the variant that’s prevalent right now.

However, according to Pearson, the good news is that “we do have one monoclonal antibody product that does retain activity: bebtelovimab.”

How to Get Treatment

Pearson said the key to using either antiviral or monoclonal antibody treatments is starting them as soon as symptoms or a positive test result are noted. Ideally, treatment should start within five days to be effective.

Jeffrey Pearson, PharmD

The biggest thing is, if you have symptoms, have yourself tested.

— Jeffrey Pearson, PharmD

If you have tested positive for COVID, contact your healthcare provider right away. They can prescribe the best course of treatment if you are eligible.

According to the Department of Health and Human Services (HHS), providers, pharmacies, and health clinics can also provide COVID treatments. HHS has a website to help you find treatment near where you live.

“The biggest thing is, if you have symptoms, have yourself tested,” said Pearson. “It doesn’t need to be a PCR test. Get yourself tested at home.”

If you have symptoms of COVID but don’t have any at-home tests, go to a test-to-treat site (which you can find on the HHS website). You can take a rapid COVID antigen test and immediately get a prescription to be filled on site.

According to Pearson, a “positive test is enough to get treatment if you have one of the high-risk factors or if you’re over age 65.”

Once you’ve confirmed that you have COVID and you have risk factors that make it more likely you’ll get seriously ill, remember that you have a limited window of opportunity for the treatments to be effective. In other words, don’t wait.

As Pearson noted, “the number of patients that we have coming in looking for treatment mostly on day 8+ and they don’t qualify for treatment is kind of heartbreaking.”

That said, no COVID treatment is meant to replace getting vaccinated. The available COVID vaccines are still the best way to protect yourself and those around you.

What This Means For You

There are treatments for COVID-19, including antivirals and monoclonal antibodies. However, you have to start them as soon as possible—ideally within five days of feeling sick or having a positive test. There are now test-to-treat sites throughout the U.S., where you can be tested for COVID and get a prescription for these treatments.

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.

2 Sources
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. Gandhi RT, Malani PN, del Rio C. COVID-19 therapeutics for nonhospitalized patients. JAMA. 2022;327(7):617-618. doi:10.1001/jama.2022.0335

  2. Petty LA, Malani PN. Oral antiviral medications for COVID-19. JAMA. Published online April 25, 2022. doi:10.1001/jama.2022.6876

By Valerie DeBenedette
Valerie DeBenedette has over 30 years' experience writing about health and medicine. She is the former managing editor of Drug Topics magazine.