For decades, vaccine researchers have been enchanted and frustrated with the promise of messenger RNA. The tiny snippets of genetic code are essential in telling cells to build proteins, a basic part of human physiology — and key to unleashing the immune system.
But they’ve been hard to tame, at least until the coronavirus spurred a global race to create a vaccine.
Now, both Pfizer and Moderna are testing their separate vaccine candidates that use messenger RNA, or mRNA, to trigger the immune system to produce protective antibodies without using actual bits of the virus. If the experimental coronavirus vaccines win approval from the Food and Drug Administration, they will be the first-ever authorized vaccines that use mRNA — a development that would not only turn the tide in this pandemic but could also unlock an entirely new line of vaccines against a variety of viruses.
The two experimental vaccines have some key differences that…