a Division of Cancer Epidemiology, Faculty of Medicine , McGill University , Montréal , Canada.
Expert Rev Vaccines. 2018 May;17(5):395-409. doi: 10.1080/14760584.2018.1471986. Epub 2018 May 21.
Vaccine herd effects are the indirect protection that vaccinated persons provide to those who remain susceptible to infection, due to the reduced transmission of infections. Herd effects have been an important part of the discourse on how to best implement human papillomavirus (HPV) vaccines and prevent HPV-related diseases.
In this paper, we review the theory of HPV vaccine herd effects derived from mathematical models, give an account of observed HPV vaccine herd effects worldwide, and examine the implications of vaccine herd effects for future cervical cancer screening efforts.
HPV vaccine herd effects improve the cost-effectiveness of vaccinating preadolescent girls, but contribute to making gender-neutral vaccination less economically efficient. Vaccination coverage and sexual mixing patterns by age are strong determinants of herd effects. Many countries worldwide are starting to observe reductions in HPV-related outcomes likely attributable to herd effects, most notably declining anogenital warts in young men, and declining HPV-16/18 infection prevalence in young unvaccinated women. Policy makers making recommendations for cervical cancer screening will have to consider HPV vaccination coverage and herd effects, as these will affect the positive predictive value of screening and the risk of cervical cancer in unvaccinated women.
疫苗群体效应是指接种疫苗的人因感染传播减少而对仍易受感染的人提供的间接保护。群体效应一直是关于如何最好地实施人乳头瘤病毒（HPV）疫苗和预防 HPV 相关疾病的讨论的重要组成部分。
本文回顾了从数学模型中得出的 HPV 疫苗群体效应理论，描述了全球观察到的 HPV 疫苗群体效应，并研究了疫苗群体效应对未来宫颈癌筛查工作的影响。
HPV 疫苗群体效应提高了为青春期前女孩接种疫苗的成本效益，但也使得针对所有性别的疫苗接种效率降低。疫苗接种覆盖率和按年龄划分的性混合模式是群体效应的重要决定因素。全球许多国家开始观察到 HPV 相关结果的减少，这可能归因于群体效应，最明显的是年轻人中肛门生殖器疣的减少，以及年轻未接种疫苗的女性中 HPV-16/18 感染率的下降。制定宫颈癌筛查建议的政策制定者将不得不考虑 HPV 疫苗接种覆盖率和群体效应，因为这将影响筛查的阳性预测值和未接种疫苗的女性宫颈癌的风险。
