Clinical Pearls & Morning Reports

Posted by Carla Rothaus

Published May 10, 2023


How effective is HPV vaccination?

Human papillomavirus (HPV) infection is a common sexually transmitted infection. Most HPV infections are not noticed; more than 90% of new infections clear or become undetectable within 1 to 2 years. Persistent infection with some HPV types can progress over a period of years to cervical cancer as well as to other anogenital cancers, including cancers of the vagina, vulva, penis, and anus, and to cancer of the oropharynx. Read the NEJM Clinical Practice Article here.

Clinical Pearls

Q: Which HPV type causes most of the HPV-attributable cancers in women and men?

A: More than 200 different HPV types have been identified, including approximately 40 types that infect mucosal epithelium. Twelve types have been defined as oncogenic (or high-risk), and 8 to 12 types as probably or possibly oncogenic. Among the oncogenic HPV types, HPV16 is the most likely type to progress to cancer and causes most of the HPV-attributable cancers in women and men.

Q: How effective is HPV vaccination?

A: International, randomized, controlled trials involving female adolescents and women 15 to 26 years of age have shown vaccine efficacy of at least 96% for the prevention of cervical precancers (cervical intraepithelial neoplasia grade ≥2 or adenocarcinoma in situ) owing to vaccine-targeted HPV types in per-protocol populations ― women who had no evidence of infection with or exposure to a given HPV type at the time of vaccination and had received all three vaccine doses. Studies have shown long-lasting protection after vaccination. There is no evidence from clinical trials that vaccination can prevent the progression of preexisting infection to disease or can promote the clearance of infection or disease already present at the time of vaccination.

Morning Report Questions

Q: Have any safety concerns emerged since HPV vaccination was first implemented?

A: Safety data regarding HPV vaccines from prelicensure vaccine trials and from more than 15 years of postlicensure monitoring provide extensive reassuring evidence regarding safety. Through 2021, more than 135 million doses of HPV vaccine had been distributed in the United States. Early safety monitoring data showed that syncopal episodes can occur after HPV vaccination, as can occur after other vaccinations in adolescents; recommendations were made for adolescents to be seated when vaccinated and to be observed after the immunization. U.S. vaccine safety monitoring systems as well as special evaluations and postlicensure studies in other countries have not confirmed any other safety signals aside from rare allergic reactions. Large population-based evaluations of general safety, death, autoimmune conditions, and neurologic conditions have shown no safety concerns.

Q: What is the recommended schedule for HPV vaccination?

A: Since 2006, routine HPV vaccination has been recommended for girls 11 or 12 years of age; vaccination can be started at as young as 9 years of age. Boys were included in the vaccination program in 2011. Vaccination is also recommended through 26 years of age for previously unvaccinated persons (catch-up vaccination). Ideally, vaccination should occur before the onset of sexual activity. In 2019, shared clinical decision making was recommended for persons 27 to 45 years of age. HPV vaccination coverage has increased gradually but remains lower than the approximately 90% coverage that has been achieved for other vaccines recommended for adolescents. Coordinated efforts between health care providers and public health officials are needed to provide catch-up vaccinations to persons who missed vaccinations earlier and to address vaccine hesitancy.

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