Drug makers say they are confident emerging antiviral drugs will prove effective in combatting the Omicron variant even as they acknowledge that existing vaccines provide less protection against the new strain.
Pfizer CEO Albert Bourla told CNBC this week that he has a “very high level of confidence” that Pfizer’s antiviral pill “will not be affected by this [Omicron] virus.” Pfizer’s pill, called paxlovid, reduced deaths and hospitalization by 89% among COVID-19 patients in clinical trials, but the U.S. Food and Drug Administration is still reviewing Pfizer’s application to authorize the drug for emergency use.
Pharmaceutical giant Merck, which developed an antiviral pill called molnupiravir, also said Tuesday that it expects its drug, which reduced the risk of deaths and hospitalizations by 30% against other COVID-19 variants, to perform similarly against Omicron. This week, a Food and Drug Administration panel voted to recommend that the agency approve Merck’s antiviral pill for emergency use, and a final decision on its approval could come later this month.
The WHO labelled Omicron a “variant of concern” on Friday after it was first detected in South Africa, and since then over twenty countries have confirmed Omicron cases and while dozens more have imposed travel bans or other curbs to keep or delay the variant from entering their borders due to concerns that Omicron might be more transmissible and vaccine-resistant than previous variants.
“I think the result could be, which we don’t know yet, the vaccines protect less [against Omicron than the Delta variant],” he said. Pfizer’s mRNA COVID-19 vaccine, co-developed with Germany’s BioNTech, is one of the most widely deployed vaccines in the world and has proven highly effective in limiting transmission of Delta and preventing hospitalizations and deaths from the globally dominant strain. Moderna CEO Stephane Bancel also said Tuesday he expects a “material drop” in the effectiveness of Moderna’s mRNA COVID-19 vaccine against Omicron compared to Delta.
Dr. Siddharth Sridhar, a clinical virologist the Hong Kong University’s medical school, says the difference between how Pfizer’s antiviral pill and its vaccine will perform against Omicron comes down to the new variant’s unique mutations.
Most of Omicron’s mutations are concentrated on the spike protein, the part of the virus that binds cells to our bodies, he said. “The spike protein has been a big target all along for vaccine manufacturers, because, theoretically, if you can get antibodies [to protect] against the spike protein that protects you from infection,” he said. Sridhar said he expects existing vaccines to still provide a “decent” level of protection against severe disease and death from Omicron, but the “number and type of mutations” in the variant suggests that the vaccines may lose some potency.
But the process through which antiviral pills elicit an immune response is “completely independent of what goes on in the spike,” he says. Instead, antiviral pills from Merck and Pfizer target proteins that have relatively fewer mutations in Omicron, making it more likely that the antiviral pills will remain effective against the variant.
