We're halfway through 2014 and there have been more than 3400 whooping cough cases reported in California during that period of time. This is way more than in 2013, when the epidemic started. And yes, you can thank anti-vaxxers for that.
According to CBS Sacramento, the most at-risk population for whooping cough is infants, and that the best way they can get protected is if their mothers are vaccinated in the third trimester. However, vaccination rates of course are down, especially in school-age children. This is contributing to the spike in cases, even though whooping cough is a disease that peaks every 3-5 years.
Some more alarming numbers: The state health department has had over 800 cases reported to them in the last two weeks. Last year, Sacramento County saw 74 cases of whooping cough; this year the caseload has already increased to 177.