Pfizer and BioNTech have started a U.S. trial of COVID-19 vaccine candidates at the NYU Grossman School of Medicine and the University of Maryland School of Medicine.

The phase 1/2 study will assess the safety, immunogenicity and optimal dose of four mRNA vaccine candidates in a single, continuous trial. The first stage will enroll up to 360 healthy subjects between the ages of 18-55 and 65-85 years of age.

The drugmakers are also conducting the trial in Germany — the first COVID-19 vaccine trial in that country.