evidence: RNA vaccines rose to prominence during COVID, but we've only scratched the surface of their potential [...] Vaccines that contain messenger RNA, or mRNA, have been studied for decades, but the release of them during the COVID-19 pandemic was the first of its kind. Both Pfizer and Moderna developed mRNA vaccines that work by delivering a blueprint to the body in the form of genetic material — which the body then uses to build proteins and mount an immune defence.