Why Getting Stressed About a Shot Is Actually Good It whips up the immune system, making vaccines more effective: researcher By John Johnson, Newser Staff Posted May 26, 2013 9:45 AM CDT 0 comments Comments (Shutterstock) (Newser) – Hate the idea of getting poked by a needle at the doctor's office? Congratulations, new research suggests you're actually making the shot more effective. As Scientific American explains, a team of Stanford researchers found that mice exposed to minor stress before getting vaccinated were better able to fight off infection than their non-stressed counterparts. The idea is that the stress whips up the body's immune system and gives the inoculation an added boost. "Something similar seems to happen to people," writes Ferris Jabr. The same team found that people about to have knee surgery had more immune cells in their bloodstream in the days before surgery. The brain is telling the body to prepare to heal, in similar fashion to the way that the spleen and other organs pump out immune cells in a "fight or flight" situation. Exactly how stress interacts with the body's healing remains a complicated picture, but this generally meshes with an emerging school of thought that short-term stress can be a good thing—in contrast to debilitating, long-term stress, notes the Smithsonian.