Why did so many California kids get whooping cough despite being vaccinated?

When California had its biggest pertussis outbreak in more than half a century in 2010, the kids who fell sick most were 10- and 11-year-olds. That struck public health experts as odd. Children receive five doses of the vaccine that protects against the illness — also known as whooping cough —...
Source: L.A. Times - Health - Category: Consumer Health News Authors: Source Type: news