Question

When should vaccines be given? Should they be given as a precaution or when there is evidence of an outbreak?

Answer 1

Among reported cases through May 17, 90% were unvaccinated or their vaccination status was unknown. Fifty-five (6%) cases were acquired outside of the U.S. (international importations) and 825 (94%) were acquired in the U.S. Most cases (94%) were related to outbreaks and 75% were related to outbreaks in New York City and New York State.