Flu Shots Go Zero-Gravity for NASA Research

Astronaut Scott Kelly got his flu shot aboard the International Space Station.

— -- Flu shots are going zero-gravity -- or micro-gravity to be exact -- thanks to a new NASA project that aims to examine how a human's immune system is affected while in space.

Astronaut Scott Kelly, who is aboard the International Space Station for a year, got a flu shot today even though he's unlikely to encounter any infected people while in space. The goal is to examine how his immune system, along with the immune system of his earthbound identical twin brother astronaut Mark Kelly, respond to the shot.

The experiment is part of the "Immunome Changes in Space Investigation” led by scientists at Stanford University, according to the NASA website. The program aims to find out if an astronaut’s immune system changes due to micro-gravity or other stresses of spaceflight, including increased radiation and altered nutrition.

The experiment could shed light on how the immune system is affected by space travel.

"In space, some aspects of the immune system appear weakened, which could lead to infections. Other aspects appear overactive, which could cause allergy or hypersensitivity," NASA explained on its website.

Scott Kelly showed off his flu shot on Twitter today, saying “Got a flu shot in space today for @ISS_Research. Your turn, @ShuttleCDRKelly!”

Dr. William Schaffner, an infectious disease expert at Vanderbilt University Medical Center, told ABC News it will help to have twins involved in the research.

“It’s a very clever idea to use twins to examine this. ... Their immune systems should be identical,” he said. “Previous NASA studies have looked at some aspects of immune system and they believe that for people in space that at least some elements of the immune system as measured differ from what would be expected down here on Earth.”

In the experiment, scientists could see how well the flu vaccine spurs antibodies both here on Earth and miles into space, Schaffner said, explaining “now they’re putting theoretical issues to the test.”

“Do they both rise equivalently?” Schaffner said of the twins’ antibody levels. “There are also some more sophisticated test they could do by harvesting white blood cells from each of the two twins and see how well they function when they are exposed to influenza virus.”