New clue about whooping cough epidemic from CDC investigators

Jul 20, 2012

Federal health investigators say a new clue has emerged about the whooping cough epidemic in Washington.

The epidemic shows no signs of waning – and the U.S. is on track to have more whooping cough cases than any time in 53 years. Washington and Wisconsin have the biggest outbreaks this year, with 3,000 reported cases each.

The federal Centers for Disease Control and Prevention, based in Atlanta, looked into the epidemic in Washington. They found evidence that the whooping cough (or, pertussis) vaccine might be wearing off more quickly than anyone expected – within a few years of the last booster shot.

During this year’s epidemic, the highest rates of infection are among ten-year-olds and 13-to-14 year-olds.  In between, at age eleven, they typically get a booster shot, and the data shows that infections drop off, temporarily. 

"That is different than what we saw in previous waves of pertussis.  The increased number of cases among 13-to-14 year olds is a concern we are looking at in detail.  There are a number of possible causes, including how long protection from the vaccine lasts," says Dr. Anne Schuchat, director for the National Center for Immunization and Respiratory Diseases at the CDC.

A newer version of the pertussis vaccine was introduced in the late 1990’s, because it has fewer side effects. Now, the CDC is wondering if it lasts as long, and especially, if it might require a more frequent booster shot for teenagers and adults.

Health officials say the vaccine is still the best protection available and is helping limit the epidemic. They’re urging adults and teenagers to get a booster shot.

The vaccine makes symptoms less severe and protects any babies you may come in contact with.  The disease can be fatal to infants during their first year, before they're fully immunized. There haven't been any deaths this year in Washington, but nine babies have died nationally. Many more have been hospitalized.

Whooping cough tends to spread in waves across the country, every few years. The question is, why has this year been worse than in 2010 and other recent years?

Federal officials say this outbreak is not being driven by parents who refuse to vaccinate or delay vaccinating their children.