SARS-CoV-2 variants already are showing mutations that may make them resistant to the antiviral COVID-19 pill Paxlovid and at least one other approved antiviral drug, according to researchers from the University of Minnesota Medical School.
Drug-resistant variants of the virus have appeared in different parts of the world, the investigators found in a study published March 29 in Science Advances. These variants have shown resistance to nirmatrelvir, the active component of Paxlovid that stops the SARS-CoV-2 virus from replicating.
Other variants currently in circulation also can resist ensitrelvir (Xocova), an antiviral that has been approved in Japan, the researchers reported.
Although researchers continue to work on new treatments for COVID-19, changes occurring in the SARS-CoV-2 virus could eventually undermine the efficacy of the only antiviral drugs now available, the researchers said. In the United States, Paxlovid is a first-line treatment choice for people aged 12 and older who have mild to moderate COVID-19 and who are at risk of developing serious illness.
There is a silver lining to the situation however, the authors of the current study noted. Although their research has uncovered the existence of SARS-CoV-2 variants that have resistance to two different drugs, “the good news is that their resistance profiles are distinct,” Reuben Harris, PhD, said in a statement. “This means that if one of these drugs fails due to emergence of resistance in viral variants, the other drug may still work.”
The researchers are encouraging the development of new antiviral drugs with different mechanisms of action and resistance profiles. This will expand the available range of treatments and give clinicians and patients alternative treatment options, they concluded.
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