Federal health experts are now recommending that all boys be routinely vaccinated against human papillomavirus, or HPV.

The vaccine already has been recommended for girls and young women since 2006 largely to prevent cervical cancer. But health authorities never expressly encouraged the vaccine for young boys, saying only that they “could” receive it to protect against genital warts and certain cancers and to help prevent the spread of HPV.

In releasing a new immunization schedule on Thursday - published in The Annals of Internal Medicin - the Centers for Disease Control and Prevention used much stronger language, explicitly recommending HPV vaccination for boys 11 to 12 years old and catch-up vaccination for those 13 to 21.

The move came about because health authorities were swayed by new data in the past two years showing that the vaccine is “very effective” in preventing genital warts in men and women and some cancers, said Eileen Dunne, a C.D.C. scientist. HPV infection can increase the risk of several cancers, including cervical, anal and oropharyngeal cancers affecting the back of the tongue and the throat.

The new recommendation comes on the heels of a report last week showing that roughly 1 in 15 Americans are infected with oral HPV, and that the disease is especially common among men. HPV is typically found in the genital area, affecting up to 80 percent of men and women at some point in their lives, but can be transmitted to the mouth area by intimate contact, including oral sex.

In addition to the change in HPV vaccinations in the new schedule, health officials recommended that people with Type 1 or 2 diabetes be vaccinated against hepatitis B. The hepatitis vaccine has been recommended for a number of years for people at risk of “blood exposure,” like health care workers, injection drug users and people with end-stage renal disease, who have to undergo dialysis, said Carolyn Bridges, associate director for adult immunizations at the National Center for Immunization and Respiratory Diseases at the C.D.C.

She said that diabetics have twice the risk of getting hepatitis B as others, and that health officials had recorded hepatitis outbreaks at nursing homes among people who shared devices that test blood sugar levels.

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By ANAHAD O’CONNOR