As the COVID-19 pandemic moves into its third year, new treatment options to combat the coronavirus disease are being authorized by the U.S. Food and Drug Administration. In December, 2021, the FDA issued emergency use authorization (EUA) for two oral antiviral treatments for COVID-19, Molnupiravir and Paxlovid.(1,2)
This comes at a crucial time in the pandemic as new variants emerge and COVID-19 cases are rapidly increasing since the first U.S. Omicron case was reported on December 1, 2021.(3) Effective antivirals may decrease the impact of the current public health emergency by reducing the risk of severe illness, hospitalization, and allowing accessibility to treatment for high-risk patients. Merck’s Molnupiravir is a nucleoside analogue that inhibits SARS-CoV-2 replication by viral mutagenesis for the treatment of mild-to-moderate coronavirus disease in adults with positive results of direct SARS-CoV-2 viral testing, who are at high risk for progressing to severe COVID-19, and for whom alternative COVID-19 treatment options authorized by FDA are not accessible or clinically appropriate.(4) The study showed that Molnupiravir significantly reduced the risk of hospitalization or death from 14.1% (53/377) in the placebo group to 7.3% (28/385) in the Molnupiravir group (absolute risk reduction 6.8%; 95% CI: 2.4, 11.3; p=0.0012), for a relative risk reduction of 48%. (4)
Pfizer’s Paxlovid, includes nirmatrelvir, a SARS-CoV-2 main protease inhibitor, and ritonavir, an HIV-1 protease inhibitor and CYP3A inhibitor. (6) Nirmatrelvir blocks the activity of the SARS-CoV-2-3CL protease, an enzyme that the coronavirus needs to replicate. Administration along with a low dose of ritonavir helps slow the metabolism of nirmatrelvir, thus remaining active in the body for a longer period of time at higher concentrations to help fight the virus. In clinical trials, Paxlovid was found to reduce the risk of hospitalization or death by 89% compared to placebo in non-hospitalized high-risk adults with COVID-19.(7) Until recently, COVID-19 treatments (monoclonal antibodies and remdesivir) have been only available in hospitals because they are intravenous medications, and although the authorization of oral antivirals may seem as light at the end of the tunnel, the availability of these novel therapies is concerning.(8) While the supply is expected to increase, allocation varies by jurisdiction/ facility and is not comparable to the supply of vaccines. To place in perspective, the United States ordered 13 million courses of oral antiviral therapies, short of the 200 million vaccine doses ordered when they first launched in 2021.(9)
Nevertheless, vaccination remains the best protection against serious illness, hospitalization, and death from COVID-19, since neither Paxlovid nor Molnupiravir are authorized for pre-exposure or post-exposure prevention of COVID-19. These FDA Emergency Use Authorizations represent an important milestone in the fight against COVID-19.
By Yesenia MoralesTechnical Support,