CNN  — 

Ian Haydon helped test Moderna’s coronavirus vaccine last year. Now, he’s helping test the tweaked version of that vaccine designed to fight a new, more contagious variant.

“A year ago I tried the Moderna vaccine to see if it was safe. (Spoiler: It is!) Now, on my #COVIDvaccine anniversary, I’m happy to share that I just got a 3rd dose. This booster experiment will reveal (1) if strain-adapted vaccines boost immunity & (2) whether they are safe,” Haydon, a communications specialist at the University of Washington, said via Twitter last Saturday.