WASHINGTON STATE -- Washington’s whooping cough epidemic passed 3,000 reported cases this week, just as new research shows vaccine protection wears off sooner than previously thought. State Secretary of Health Mary Selecky says it's one reason why most whooping cough cases in Washington are in school-age children who are vaccinated. She says health officials want to make sure that all children are up to date on their vaccinations. Pharmacies and health providers have free whooping cough vaccinations for adults who are uninsured or cannot afford it. The disease can be deadly to infants. A report published yesterday by the centers for disease control and prevention shows more reported cases among 13 to 14-year-olds in our state. A 2010 study showed that whooping cough vaccine protection decreases to about 70 percent after five years.