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Antivirals for COVID-19: What You Need to Know

Medically Reviewed by Dan Brennan, MD on December 25, 2022

What Are Antiviral Drugs?

Antiviral medications help your body fight off viruses that cause disease. They can reduce the symptoms of your viral infection and shorten the length of your illness.

In most cases, viruses clear up without these drugs. But if your infection is ongoing or life-threatening, like in some cases of COVID-19, your doctor may want to treat you with an antiviral medication.

There are two major ways to take antiviral drugs: by mouth or through a vein. You take oral antiviral pills at home. You get intravenous (IV) antivirals from a health care professional.

The antiviral that doctors prefer to use to treat certain cases of COVID-19 is a pill called nirmatrelvir-ritonavir(Paxlovid). While Paxloid has only received emergency use authorization from the FDA, it is preferred over remdesivir (Veklury), which given by IV is the only antiviral drug that has full FDA approval. A EUA has also been given to the antiviral molnupiravir (Lageviro) but that should only be used when the other treatments are not available.

What to Know About Paxlovid

Paxlovid is a prescription COVID-19 pill from Pfizer and is used to treat adults and children 12 and older (weighing at least 88 pounds) who have mild-to-moderate COVID-19 and high risk of the disease becoming severe.

Take Paxlovid as soon as possible after you’re diagnosed and within 5 days of your symptoms starting.

It includes nirmatrelvir, which helps the virus stop multiplying. It also includes ritonavir, which helps nirmatrelvir stay in your body longer at higher concentrations.

Each dose of Paxlovid is made up of three tablets: two of nirmatrelvir and one of ritonavir. You take the tablets together by mouth twice a day for 5 days, for a total of 30 tablets. The FDA didn’t authorize Paxlovid to be used longer than 5 days in a row.

Pfizer says the drug may lower the chances of dying or needing to go to the hospital by 89% for adults who have COVID and also a high risk of it becoming severe.

COVID Rebound After Taking Paxlovid

Some people who recover from COVID-19 get symptoms again about 2 to 8 days later. Or they get a “positive” test result that says they have COVID after they already got a “negative” result that didn’t find signs of the disease.

Doctors call this a “COVID rebound,” and it’s possible to have it whether you got the COVID vaccine or not. It’s also possible to have a rebound after you finish taking a 5-day course of Paxlovid.

The CDC says it hasn’t had any reports of a COVID rebound causing severe disease. If you have a rebound, you shouldn’t need more treatment with Paxlovid or another drug, the agency and other experts say.

But you should take these steps to help keep other people safe:

  • Stay home (or isolate) for at least 5 days. Stay in a separate room from others who live with you, and wear a well-fitting mask when you need to be around them. You can stop isolating after 5 full days if you’ve had no fever for 24 hours (without using fever-reducing drugs) and your symptoms are improving.
  • Continue wearing a mask for a total of 10 days after your rebound symptoms started. If test results say you still have COVID after 10 days, talk to your doctor. At this point, you’re less likely to be contagious, the CDC says.

Other Antiviral Drugs for COVID-19

If you can’t take Paxlovid, other antiviral medicines can help:

Molnupiravir(Lageviro). Merck Sharp and Dohme (MSD) developed this medication. The FDA also gave it an emergency use approval. You take this pill by mouth to treat COVID-19.  

Molnupiravir is safe and effective for people with mild to moderate COVID-19 who are at a higher risk of severe illness. Data shows it can lower your risk of death or hospitalization from a COVID-19 infection.

This medication interferes with the COVID-19 virus’s ability to make copies of itself. This stops the spread of the virus throughout your body. So, your body’s virus level will be low, and you won’t have as intense symptoms.

Clinical trials show that molnupiravir works best when you take it in the early stages of a COVID-19 infection. Experts suggest you take this pill as soon as possible after you receive a positive test and within 5 days of your first symptoms.

Molnupiravir is recommended for people who have mild to moderate COVID-19 or who have at least one risk factor for severe illness with COVID-19. It’s not recommended for pregnant women because animal studies suggest it might harm babies.

Remdesivir (Veklury) The FDA approved this drug to treat COVID-19 in adults and children 28 days and older who weigh at least 7 pounds.

This is an intravenous treatment, and it’s only available in hospitals or certain outpatient health care settings. Remdesivir stops the virus that causes COVID-19 from making copies of itself so that you can recover quicker.

While you may have heard of other antiviral therapies, experts don’t recommend all of them for COVID-19 treatment. Guidelines advise against the use of chloroquine or hydroxychloroquine and/or azithromycin, lopinavir/ritonavir and other HIV protease inhibitors, and nitazoxanide (except in clinical trials) for people with COVID-19.

Similarly, there’s not enough evidence to support the use of the drug ivermectin for COVID-19 treatment. Experts need to do more research.

How Effective Are Antiviral Drugs in COVID-19 Treatment?

Research shows that both oral antiviral treatments have been shown to lower your risk of hospitalization and death if taken within the first 5 days of infection.

Studies show that remdesivir reduced the risk of serious complications with COVID-19 and helped people get better with the virus. But the same study also showed it didn’t affect your risk of death after the 14th day of treatment.

While these treatments work well for people with COVID-19, they’re not meant to replace the COVID-19 vaccine.

Show Sources

SOURCES:

Mayo Clinic: “Study finds few COVID-19 patients get rebound symptoms after Paxlovid treatment.”

Up to Date: “COVID-19: Outpatient evaluation and management of acute illness in adults.”

Cleveland Clinic: “Antivirals.”

Gov.uk: “First oral antiviral for COVID-19, Lagevrio (molnupiravir), approved by MHRA.”

National Institutes of Health: “Antiviral Therapy,” “Remdesivir,” “Table 2a. Remdesivir: Selected Clinical Data.”

Pfizer: “Pfizer’s Novel COVID-19 Oral Antiviral Treatment Candidate Reduced Risk of Hospitalization or Death by 89% in Interim Analysis of Phase 2/3 EPIC-HR Study.”

Journal of Pharmacy and Pharmaceutical Sciences: “Safety and Efficacy of Remdesivir for the Treatment of COVID-19: A Systematic Review and Meta-Analysis.”

FDA: “Coronavirus (COVID-19) Update: FDA Authorizes First Oral Antiviral for Treatment of COVID-19.”

CDC: “What’s new in the Guidelines,” “COVID-19 Rebound After Paxlovid Treatment,” “Quarantine and Isolation.”

News release, Pfizer.

News release, Merck.

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