Pillar 10
Antiviral Strategies and Antiviral Therapeutics

The study evaluated over 78,000 SARS-CoV-2 genomes, looking for the development of resistance mutations to a newly approved oral antiviral against SARS-CoV-2, called Nirmatrelvir-ritonavir. The team looked for specific mutations in the main viral protease encoded by nsp5, which confers resistance to Nirmatrelvir-ritonavir. Mutations in the nsp5 gene were found in a small number of SARS-CoV-2 isolates in Ontario (0.16%), but it was unclear if these mutations were due to antiviral pressure or random mutations because of viral replication. These findings suggest that significant resistance to Nirmatrelvir-ritonavir has not developed yet, but with increased clinical use, continued surveillance for anti-viral resistance variants is important to inform clinical practice, vaccine development and public health policy.

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Prevalence of Low-Frequency, Antiviral Resistance Variants in SARS-CoV-2 Isolates in Ontario, Canada, 2020-23. Calvin Sjaarda, Lynette Lau, Jared Simpson, Ramzi Fattouh, Mia Biondi, Finlay Maguire, Aaron Campigotto, Yujia Feng, Kyla Tozer, Henry Wong, Wilson Sung, Sean Kim, Christian Marshall, Prameet Sheth, Robert Kozak. JAMA Network Open. 2023.07.21.2807483; https://jamanetwork.com/journals/jamanetworkopen/fullarticle/2807483