There was recently an epidemic in California that sickened thousands of people and killed eight babies. Also, smaller outbreaks have been reported in other states.
So what's happening? Pertussis outbreaks can crop up every three to five years, but no one knows exactly why it seems to be hitting harder. Some blame international travel, better detection and not getting your child vaccinated or giving them a booster.
A new study shows vaccination rates for children insured by commercial health insurance plans dropped almost 4 percentage points over a one-year period
It is believed many higher income parents are choosing to forgo kids' vaccinations for fear of side effects.