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Researchers report that antiviral treatments still work well against COVID-19. PIKSEL/Getty Images
  • Researchers report that COVID-19 antiviral treatments work better against the Omicron variant than antibody therapies.
  • Experts say the reason is antiviral treatments are designed to disrupt the novel coronavirus’ manufacture of important proteins.
  • They note that the availability of antiviral and antibody medications is still an issue.
  • They add that getting vaccinated is still the best way to avoid needing any treatment for COVID-19.

As the Omicron variant has become the dominant COVID-19 strain, antiviral treatments are holding up better than antibody therapies, a study published Jan. 27 suggests.

Researchers from the University of Wisconsin-Madison report that two antiviral drugs by Merck – molnupiravir and the intravenous drug remdesivir – were just as effective at treating the Omicron variant as previous variants of the novel coronavirus.

Researchers also concluded that an intravenous drug by Pfizer that’s similar to its Paxlovid pill also mounted a robust defense against the virus.

Four antibody treatments were all less effective at treating Omicron, with antibodies from Eli Lilly and Regeneron unable to treat the virus at all, researchers reported.

“The bottom line is we have countermeasures to treat the Omicron variant. That’s good news,” Yoshihiro Kawaoka, PhD, the lead study author and a professor of virology at the University of Wisconsin, said in a press release. “However, this is all in laboratory studies. Whether this translates into humans, we don’t know yet.”

Nonetheless, the findings regarding Lilly and Regeneron’s antibody therapies were conclusive enough that the Food and Drug Administration (FDA) has revoked its emergency use authorization for these two drugs, which were once the forerunners of antibody treatment against the disease.

To understand why antivirals are working where some antibody treatments have failed, you have to know how each works to fight the virus.

“Most antivirals disrupt a critical step in the virus’ ability to direct the manufacture of proteins (paxlovid) or cause errors to be introduced into the protein development, which causes inactive proteins to be made (molnupiravir),” Dr. William Lang, the medical director of WorldClinic, told Healthline.

That mechanism is unlikely to be significantly affected by mutations to the virus. Not so with antibody therapies.

“Antibodies physically are very dependent on actual cellular geometry, meaning that to work, the actual physical shape of their target on the virus cannot change much,” Lang said. “Unfortunately, with two of the three major monoclonal antibodies, the geometry changes were enough that they lost their ‘lock and key’ matching and have become less effective.”

One antibody treatment, sotrovimab, still works because it targets a more stable part of the virus that hasn’t been affected by Omicron mutations, Lang added.

On November 30, 2022, the Food and Drug Administration (FDA) deauthorized bebtelovimab for emergency use in the United States. This was the last monoclonal antibody drug authorized by the FDA to treat COVID-19. The decision was made because it is not expected to neutralize new Omicron subvariants.

Effectiveness is one thing, but if you want to receive antiviral or antibody therapy, those treatments can still be difficult to come by.

One reason is that COVID-19 vaccines were initially so effective at preventing infection that they slowed the production of antivirals and antibodies.

“Because the government elected not to resource multiple approaches in a manner similar to the ‘warp speed’ program for vaccine development, this means that the manufacturing capability for these lifesaving treatments just isn’t there, and we are just now ramping up processes that could have been in place months earlier,” Lang said.

But as production ramps up, antivirals – especially those in pill form – are likely to play an increasingly prominent role in COVID-19 treatment.

“When available, antiviral drugs are easy to take in that they are a 5-day course of pills that can be taken at home, whereas the antibodies require one or multiple IV infusions at an infusion center,” said Michael Botta, PhD, co-founder of healthcare marketplace Sesame. “By the summer, we expect millions more doses of antivirals to be available across the United States based on Pfizer and Merck’s production schedules.”

“Given short supply, these are being reserved for the highest risk Americans, but these restrictions will likely wane by the summer,” Botta told Healthline.

In the meantime, experts advise getting vaccinated and a booster shot if you haven’t already. While not as effective against the Omicron variant as previous strains, vaccines are still the surest way to keep you out of the hospital and from needing COVID-19 therapies.