Should I get the swine flu (H1N1) vaccine if I’ve had Guillain-Barré syndrome? —J.M., Irvington, N.Y.

That depends in part on your risk of getting swine flu and becoming seriously ill if you do. It’s true that some studies have associated flu vaccines with a slight increase (about one person per million) in the risk of developing Guillain-Barré syndrome (GBS), a neurological disorder. And some evidence suggests that a previous case of GBS increases your risk of getting it again. But the flu itself can also cause GBS as well as such complications as pneumonia and in rare cases, death. If you’re among the priority groups for H1N1 vaccination—including pregnant women, health-care workers, and people ages 25 to 64 with underlying conditions such as diabetes and heart or lung disease—the shot’s benefits probably outweigh its risks.