Merck and Pfizer are each developing a new oral antiviral drug that might prevent or treat COVID-19. The pills are very different from the antiparasitic medication ivermectin, contrary to claims online that they are “suspiciously similar” or that the companies are “repackaging” ivermectin in a ploy to increase profits.

Throughout the COVID-19 pandemic, there has not been an easy-to-take oral pill that can prevent or treat infection with SARS-CoV-2, the coronavirus that causes COVID-19. Pharmaceutical companies, however, have been working on testing novel drug candidates, and in the last few weeks both Merck and Pfizer announced developmental milestones.

On Sept. 27, Pfizer said that it was launching a late-phase clinical trial to test whether, in combination with another drug, its oral COVID-19 antiviral can prevent infection with the coronavirus. Dubbed PF-07321332, the investigational medication is a protease inhibitor that blocks a key enzyme the SARS-CoV-2 virus needs to replicate itself.