My wife had a bout of shingles last year and it was pretty horrible. I didn’t realize how debilitating it could be. The question is: why are so many young people getting it these days?

Chen points out that stress may also to play a role. “Shingles can happen among healthy young adults with no other underlying diseases and who are otherwise athletic, and sometimes we think it might be stress-induced,” he says.

Stress can suppress immune function and trigger outbreaks of cold sores and other herpes virus–related symptoms. “This is all speculation, but I think you could point to social media and modern culture and the emotional and physical and spiritual stress a lot of younger adults are feeling,” Chen says. “I don’t think this is driving higher rates, but it could be a factor.”

Sameer Vasta @vasta