AFAIU, yes, but the benefits just weren't as well understood at the time of the original debate, which as I recall revolved entirely around the ethics of vaccin

AFAIU, yes, but the benefits just weren't as well understood at the time of the original debate, which as I recall revolved entirely around the ethics of vaccinating boys for the benefit of girls. It probably also helped that by the time recommendations were more generally extended to boys there was greater confidence in safety, as HPV-associated cancer in men isn't as prevalent[1] as in women. The cost-benefit tradeoffs were different. [1] This CDC page, https://www.cdc.gov/cancer/hpv/statistics/index.htm https://www.cdc.gov/cancer/hpv/statistics/index.htm, says the ratio is ~3/4 (19900/25400), which is surprising. But that might be a modern figure. I suspect this wasn't as well known or as appreciated 15 years ago. Also, it seems that throat cancer incidence has been increasing rapidly recently (see https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-q-and-a-increasing-incidence-of-throat-cancer-related-to-hpv/ https://newsnetwork.mayoclinic.org/discussion/mayo-clinic-q-...), so actual ratio may have been much smaller 15 years ago.