The LA Times is reporting that a ninth infant has died from pertussis -- whooping cough -- this year alone in California. This is the deadliest outbreak among infants since 2005. The cause is clearly the lack of vaccinations. At least seven of the infants who died were too young to be vaccinated, which means they rely on herd immunity, the level of immunity in the population at large. Adults can carry the bacteria, and can then spread it to infants. The root cause behind the lack of immunity in California isn't clear. It may simply be that not enough adults know they need a Tdap booster (talk to your doctor!), or it may be that there is an antivaccination streak in California. Either way, the California Department of Public Health recommends everyone over 7 years old get immunized, especially people who come in contact with infants. If you live in California -- or anywhere -- PLEASE talk to your doctor about getting vaccinated, whether it's a booster or a first time shot. The cold, hard truth is that babies are dying from a preventable disease. I would dearly love to never have to write another blog post like this one.