But the COVID-19 mRNA vaccines brought a new approach to vaccine development. An mRNA drug comprises two essential components: mRNA molecules, which code for desired proteins, and the lipid molecules – such as phospholipids and cholesterol – that encapsulate them. Once inside cells, mRNA molecules instruct the cell’s machinery to produce the target protein required for a desired therapeutic effect. From a drug development perspective, mRNA drugs offer significant advantages over traditional drugs because they are easily programmable. More importantly, different mRNA drugs produced by the same set of methods will have similar properties.