Wait, why does someone need a flu shot in space?
Astronauts can indeed get sick in space, but that’s not why Scott Kelly got the seasonal vaccine. Kelly’s identical brother Michael, who is on Earth, is getting a shot, too, and NASA will take blood samples from both to compare how their systems respond to the vaccination in two extremely different environments. The data will help scientists better understand how to keep astronauts healthy in orbit, and could potentially lead to the development of treatments for arthritis, diabetes, and other immune system-related diseases.
Kudos to Scott for sticking a needle into his own arm.