The vaccines were possible only because of efforts in three areas. The first began more than 60 years ago with the discovery of mRNA, the genetic molecule that helps cells make proteins. A few decades later, two scientists in Pennsylvania decided to pursue what seemed like a pipe dream: using the molecule to command cells to make tiny pieces of viruses that would strengthen the immune system.
The second effort took place in the private sector, as biotechnology companies in Canada in the budding field of gene therapy — the modification or repair of genes to treat diseases — searched for a way to protect fragile genetic molecules so they could be safely delivered to human cells.
The third crucial line of inquiry began in the 1990s, when the U.S. government embarked on a multibillion-dollar quest to find a vaccine to prevent AIDS.