What is the impact of Merck's new antiviral pill in Covid -19 management?
First of all, I want to emphasise that the oral antiviral (if approved) similar to monoclonal antibody therapies, should not be viewed as an alternative to vaccination. Primary vaccination for eligible patients is the best way to prevent infection, illness and death from Covid-19.
Oral antivirals may have a role in prevention (post exposure before infection) and therapy (early on to prevent severe illness and hospitalisation). The advantage of this therapy would be its relative ease of delivery (vs monoclonal antibodies which require intravenous infusion).
How is molnupiravir different from other drugs approved for the treatment of Covid-19?
The Merck-Ridgeback Biotherapeutics’molnupiravir is a ribonucleoside analog that targets viral polymerase. The study of 775 adult outpatients with Covid-19 at high risk for severe disease treated within five days with the drug showed significantly decreased risk of composite outcome of death/hospitalisation (7.3 per cent vs 14.1 per cent). Pfizer oral drug (PF-07321332), also in phase 3 studies, is a protease inhibitor boosted with ritonavir. Both differ from remdesivir (the only US FDA approved antiviral for Covid-19) which is an andenosine analogue that targets the RNA-dependent RNA polymerase to block viral RNA synthesis.
What is the role of vaccines in this context ?
If proven effective, oral antivirals would add to our armamentarium against Covid-19. However, the focus should continue to be on unvaccinated susceptible individuals and global distribution of vaccine as no one is safe until all are.
Dr Steven Gordon, MD, is chairman, department of infectious disease, Cleveland Clinic, United States