By LAURAN NEERGAARD

WASHINGTON (AP) — A single HPV vaccination appears just as effective as two doses at preventing the viral infection that causes cervical cancer, researchers reported Wednesday.

HPV, or human papillomavirus, is very common and spread through sex. Most HPV infections clear up on their own but some linger, causing cancers that appear years later, including cervical cancer in women and rarer cancers in both women and men.

HPV vaccination has been recommended for U.S. girls since 2006 and already the nation is counting fewer cases of precancerous cervical lesions among women in their 20s —- the first age group to start getting the shots back when they were tweens or teens.

But cervical cancer kills about 340,000 women worldwide annually — and the new findings from a hu

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