Children who don't get the shots to prevent whooping cough are 23 times more likely to get the disease than vaccinated kids, a Colorado study suggests.
The results are especially troubling because whooping cough cases have jumped in recent years, and in rare cases the bacterial infection can be deadly.
In 2007, 10,454 cases were reported nationwide, including 10 children who died, government data show.
Authorities recommend a series of five shots, including three by age 6 months, to prevent whooping cough. A booster shot is recommended for older children and teens to guard against the vaccine wearing off.
The study involved 751 children enrolled in a Kaiser Permanente of Colorado health plan between 1996 and 2007, including 156 who got whooping cough.
Results appear in the June edition of Pediatrics, being released Tuesday.
Among kids with whooping cough, 18, or 12 percent, had parents who refused the vaccine, versus less than 1 percent of children in a comparison group who didn't get sick and included kids who had at least some of the shots. Nine children, or 6 percent, had to be hospitalized, but none died.
The results dispel vaccine-refusing parents' belief "that their children are not at risk for preventable diseases," Kaiser researcher Jason Glanz and co-authors said in the study.