What you need to know as COVID-19 vaccination efforts continue in Arizona Published Valley doctor breaks down the difference between COVID-19 vaccines In the U.S., the FDA has granted emergency use authorization for the COVID-19 vaccines developed by Pfizer and Moderna. PHOENIX - Vaccination efforts are getting underway in Arizona and other parts of the country, after two vaccines, one by Moderna, were granted emergency use authorization by the U.S. Food and Drug Administration. 1. What's the difference between the COVID-19 vaccines? While various countries have approved various COVID-19 vaccines, only the vaccines by Pfizer/BioNTech and Moderna have received emergency use authorization in the United States.