As several news sources are now reporting, results from a cohort study funded by the National Cancer Institute note that 50% of a recent study’s participants tested positively for HPV at enrollment.

Okay, that’s not quite what they’re saying. But they aren’t epidemiologists, are they?

The cohort study, conducted by researchers at the H. Lee Moffitt Cancer Center and Research Institute, gathered biomedical evidence from 1159 men (aged 18 to 70) living in Brazil, Mexico, and the United States.  I’m not quite sure how they sampled this population — the Lancet article is so fresh-off-the-press (3/1/2011) that I can only access the abstract — but it does suggest a convenience sample, “recruited from the general population, universities, and organised health-care systems” and otherwise healthy.

Researchers assessed this cohort’s health every six months for multiple years, and found an incidence rate of 38.4 per 1,000 person months (CI between 34.3 and 43). Their research also describes risk factors we’ve seen before: HPV was associated with both higher number of lifetime female sexual partners and anal sex with male partners.

If these numbers are an accurate reflection of HPV at the population level — and they probably are —  well, even more reason to have your children (female and male) vaccinated. When will the American Cancer Society, ACOG, and the ACIP update their recommendations accordingly?