[deodorel]

Actually there was that flu vaccine that triggered narcolepsy very rarely in young people after 12 - 24 months. But this is the only example i heard of.

[bayesian_horse]

Yes, but very rarely, and the cost/benefit analysis would still be positive, as compared to the virus that virtually everyone will eventually get.

Also that particular virus also caused narcolepsy, rarely, by a similar immunological mechanism.