Enlarge / A vial of COMIRNATY (Pfizer/BioNTech) and a vial of Moderna COVID-19 vaccines. (credit: Getty | Marcos del Mazo) The mRNA-based COVID-19 vaccines made by Pfizer/BioNTech and Moderna have proven highly effective at priming our immune systems to fight the pandemic coronavirus—preventing substantial amounts of infection, severe disease, and death throughout several waves of variants.