Birds on the Brain

Whooping cough’s comeback can’t be explained fully by the rising numbers of families that refuse vaccines for their children (and for parents, too), the CDC now says. It’s emerging that reformulated vaccines introduced in the 1990s aren’t as protective as older vaccines. The older, “whole cell” DTwP vaccine (it protects against diphtheria, tetanus, and pertussis) — which contained entire, dead pertussis bacteria — was phased out in 1997 due to concerns about side effects. But the new vaccine, the acellular DTaP given to babies and kids up to age 7, seems to lose effectiveness — dropping to about 70 percent protection within five years according to the Washington State Department of Health. And a booster vaccine for teens and adults, called Tdap, also seems to weaken after a few years.

As a result, whooping cough numbers are slowly rising in kids after age 7 — spiking at age 10, then dropping off for a year or two when they receive the Tdap vaccine, then rising again among 13- and 14-year-olds. Older teens who received the older vaccine as little kids seem to have better protection, the CDC says.

Family decisions to decline vaccine are contributing to the increase, the CDC says. That’s especially true in Pennsylvania and a handful of other states that allow parents to say no for personal or philosophical reasons. All states allow religious and medical exemptions. But 50% of all whooping cough in the US this year come from six states (the others are Wisconsin, Washington, Texas, Arizona and Ohio) that offer a personal or philosophical exemption.