Since human papillomavirus (HPV) vaccines were first added to the routine U.S. childhood immunization schedule nearly two decades ago, the evidence of their effectiveness has become stronger every year. In 2019, a Medicine by the Numbers in American Family Physician summarized a Cochrane review of 26 randomized, controlled trials comparing HPV vaccines to placebo. The authors found that vaccination reduced the risk of precancerous cervical lesions (cervical intraepithelial neoplasia [CIN] grades 2 or 3 and adenocarcinoma in situ) with numbers needed to treat (NNT) ranging from 55 to 73, depending on participants’ baseline HPV status. A 2021 observational study of girls and young women in England found that vaccination at ages 16-18, 14-16, and 12-13 years was associated with reductions in cervical cancer of 34%, 62%, and 87%, respectively. Remarkably, a study published this year found that 30,000 Scottish women who received at least one dose of HPV vaccine at age 12 or 13 had de...