The potential benefits of vaccines are twofold: In addition to directly protecting those who get the vaccine, they also protect those who don’t. The latter, a phenomenon called herd immunity, occurs as more and more people get vaccinated, further restricting the ease with which the disease-causing germ can spread. Now a new study suggests that the human papillomavirus (HPV) vaccine may be providing men with herd immunity against HPV infections of the throat. Oral HPV infections cause over 70% of all oropharyngeal cancers in the United States, and rates of these cancers in men have skyrocketed over the past several decades. Between 2009 and 2016, rates of HPV vaccination in both males and females increased while rates of oral HPV infection among unvaccinated men dropped, the new study showed. Results of the study, which was led by Anil Chaturvedi, Ph.D., and Barry Graubard, Ph.D., of NCI’s Division of Cancer Epidemiology and Genetics, were published September 10 in JAMA. The findings “add to accumulating evidence that HPV vaccination prevents oral infection with HPV,” said Gregory Zimet, Ph.D., of Indiana University, who studies HPV vaccine uptake but was not involved in the current study. That is “really meaningful,” Dr. Zimet added, because it is difficult to catch oropharyngeal cancers at their early, most treatable stages. More than half of oral cancers have already spread to other places in the body by the time they are discovered. Prevention of oral HPV infections today can prevent oropharyngeal cancers in the future, Dr. Chaturvedi said.