Drugmaker Merck & Co said on Friday it plans to start two large pivotal trials in September on the experimental oral antiviral COVID-19 drug it is developing with privately held Ridgeback Biotherapeutics.

Speaking on a conference call with investors, Merck's research chief Roger Perlmutter said the company has secured manufacturing capability to make "many millions of doses" of the drug before year end. The experimental drug is currently in phase 2 trials.