I wrote this article on types of COVID-19 vaccines a couple of weeks back. The technologies used in the successful Pfizer and Moderna COVID-19 vaccines are new compared to other approaches, but scientists have been developing mRNA-based vaccines for several years now. Writing this article helped me understand the different approaches to vaccine development in terms of strengths and drawbacks. We never would have had a vaccine so quickly without utilizing these new techniques, so I’m glad people had been working on them so steadfastly even before this epidemic.