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

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

Federal officials usually adopt recommendations made by the panel, 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 are considered the top killer among vaccine-preventable diseases. It’s a common complication of influenza, especially in the elderly, and is considered responsible for many of the 36,000 annual deaths attributed to flu.

The committee voted 11 to 3 to pass the recommendation, with one member abstaining. The panel also added 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. Others at the meeting made the same argument.

Dr. James Turner, who oversees student health programs at the University of Virginia, said about one in five college students smoke but he has never seen a case of serious pneumococcal disease in a student body.

“I wonder how many young people are truly benefiting from this” recommendation, said Turner, speaking as a representative of the American College Health Association.

The shot is less than perfect. First licensed in 1983, it is designed to protect against 23 strains of pneumococcal bacteria. But it hasn’t proved very effective against pneumonia, and hasn’t been very effective in warding off other pneumococcal illnesses in people with weakened immune systems and people age 80 or older.

It’s to be given to smokers as a one-time dose with no booster, but its protection drops off after five to 10 years.

Made by Merck & Co., it’s sold under the trade name Pneumovax and costs about $30 a dose.

A different vaccine — Wyeth’s Prevnar, which came on the market in 2000 — is recommended for children under age 2, and for kids 2 to 5 with certain chronic conditions or who are at higher risk for illness.

Prevnar protects against seven strains of bacteria that were the most common causes of pneumococcal diseases at the time the vaccine was developed. But lately, those strains have stopped being important causes of illness. Experts have become concerned about dozens of other strains, including some that have flourished and become resistant to antibiotics.

Wyeth has been developing a new vaccine. It is expected to present study data on it at a scientific meeting later this month, and to apply for government licensing approval early next year.