Maggie Koerth-Baker, writing for Boing Boing:
So why re-up on the Tdap before the birth of our baby? It’s all about the pertussis. Also called whooping cough, pertussis is particularly hard on infants. Pre-vaccine, it killed 4000 Americans every year, and most of them were new babies — and infections are on the rise in this country, so there’s actually a reasonable risk of a newborn coming into contact with the bacteria that causes pertussis. But the larger problem is with the pertussis vaccine, itself. It doesn’t have the staying power it once did. A little over 20 years ago, we switched the formulation for pertussis vaccines. There were good reasons for doing that — the “new” formula has fewer side effects. But it also doesn’t seem to protect people as well for as long. In fact, the protection starts to wear off within a year of vaccination.
I’m a little confused: is the vaccine actually less effective? Or does it just wear off faster?