The Whooping Cough Report

Whooping cough (pertussis) has been quite active in the US this year. Besides the much publicized, and dangerous, outbreak in California other states have reported elevated levels of whooping cough infections. Here are the numbers for the two states affected most so far (although cases have been reported in outher states/counties, but in lower numbers):

• California - experiencing what’s being billed as “its worst outbrake in half-cenury” with 2,774 reported cases, a 7-fold increase over same period in 2009, which has already killed 7 infants, all of Hispanic descent and under 2 months of age
• Michigan - 595 cases have been reported statewide through August 2010, and 902 cases were reported last year. That compares with about 330 cases a year on average between 2003 and 2008. 1 fatality, a 3 month old boy, Collin Springborn

This may sound like scare mongering, except it isn’t. We have a vaccine for pertussis. Pertussis can spread very easily, and many times it is adults that infect their children, which highlights the importance of getting the adult booster shot, Tdap.
Steven Novella has written a nice blog entry on the current pertussis epidemic where he reminds all of us that, while it may be a natural conclusion to blame the current outbreak on low vaccination rates, the data from the current epidemic is simply not in yet to support that conclusion, and that the cyclical nature of pertussis is a possible factor to account for the current outbreak.  I find that attitude very scientific, logical, and sobering, as it is very easy to let our biases color our commentary and start making unwarranted conclusions.
So to set the record straight, we have no conclusive data yet to support the hypothesis that the current pertussis outbreak is directly correlated with, or caused by, low vaccination rates. What we can say though is that we have 4 licensed acellular pertussis vaccines whose efficacy, according to the CDC  ranges from 71% to 89%. 71-89% efficacy is way better than none at all, so please vaccinate your children and take your booster shots. It helps to keep the total incidence rates low, and gives you, or your child, much better chances to avoid it completely.