An influential panel at the CDC, called the Advisory Committee on Immunization Practices has recommended that Whooping Cough (Pertussis) vaccinations be extended to all adults as well, including those aged over 65. The recommendation is in part because it is recognized that adults get the disease and then pass it to children and infants. The current vaccine, called Tdap, actually vaccinates against pertussis, tetanus and diptheria. In fact the group already recommended that adults up to the age of 65 should be vaccinated and the update is primarily because a new Tdap formulation is now effective for those over the age of 65.
This is an interesting recommendation because the last time I wrote about Whooping Cough it was because of a study here in the Bay Area (Marin actually) that showed pretty conclusively that more frequent vaccinations were needed because the gaps between booster vaccinations were too long and the vaccine was wearing off and leaving kids unprotected. Why is this important? Well, the official line is that the Tdap vaccine is effective for ten years but the Marin study suggests that is is really effective for less than that – perhaps as little as five years.
What the panel recommendation does not address is whether or not and how often adults would need booster shots. Which still leaves a lot of questions.
But first, here are some of the reasons why the panel is making the recommendation. First it is clear that pertussis (whooping cough) is more common than thought int he adult population and often goes undiagnosed and is instead thought as some other illness that is causing coughing (a cold or the flu are likely culprits). Second, pertussis is known to be highly infectious. In the 2010 outbreak in Northern California over 9,100 people were sick and 10 infants died. In the same year there were at least 21,000 cases throughout the US and rates of infection are on the rise. Pertussis is most dangerous for babies and young children and as people get older it becomes much more an inconvenience than life threatening. But fewer than 13% of the adult population are immunized against pertussis and as a result the adult population becomes a significant transmitter to infants and young children. For some more useful information on pertussis and additional reasons why you should take this recommendation seriously, see the post I wrote during the 2010 outbreak.
So, the recommendation makes lots of sense in order to keep babies and young children safer and because of the rise in prevalence of whooping cough. But what does it mean in practice? A shot every ten years seems to be what is being suggested. But the study of the California outbreak suggests shots should be every five years. And how are we going to keep track?