For the first time, an influential U.S. government panel is recommending a vaccination specifically for smokers.

The panel decided Wednesday that adult smokers under 65 should get pneumococcal vaccine. The shot is already recommended for anyone over 65. It protects against bacteria that cause bacterial pneumonia, meningitis and other illnesses.

Federal officials usually adopt recommendations made by the Advisory Committee on Immunization Practices. The vote means more than 31 million adult smokers probably will soon be called on to get the shot.

Studies have shown that smokers are about four times more likely than nonsmokers to suffer pneumococcal disease. Also, the more cigarettes someone smokes each day, the higher the odds they'll develop the illnesses.

Why smokers are more susceptible is not known for sure, but some scientists believe it has to do with smoking-caused damage that allows the bacteria to more easily attach to the lungs and windpipe, said Dr. Pekka Nuorti, a medical epidemiologist with the Centers for Disease Control and Prevention.

Pneumococcal infections kill thousands of people in the United States each year, most of them 65 years of age or older.

The committee voted 11 to 3 to pass the recommendation, adding a call for smoking cessation counseling. Some members said it might be more cost effective to recommend the vaccine for smokers who were at least age 40, because pneumococcal disease is relatively uncommon in younger smokers.