HPV Vaccine Is Already Leading to ‘Herd Immunity’

A new study suggests, albeit with very tentative optimism, that the HPV vaccine Gardasil may offer benefits even to women who don’t get inoculated through a phenomenon known as “herd immunity.” (No word yet on when this herd immunity is going to start protecting that one lonely wildebeest that gets left on the wrong side of a crocodile-infested river when the rest of wildebeests decide to go somewhere else, but I’m sure some other scientists are hard at work figuring this out because it’s super stressful to watch.)

MSNBC reports that, among women who participated in the Cincinnati-based study, researchers observed an overall decrease in the percentage of women infected with the four strains of HPV (6, 11, 16, and 18) that the vaccine guards against, as compared with rates of infection in the years preceding the vaccine’s introduction. Even with relatively low rates of women getting vaccinated, the study found that the small group of observed women achieved a degree of herd immunity, which happens when unvaccinated people are protected from a disease because a critical portion of the population has been inoculated.

Dr. Jessica Kahn and her colleagues from the Cincinnati Children’s Hospital analyzed information they gathered from two different groups of women: a group of 368 unvaccinated women who visited a Cincinnati clinic from 2006 to 2007, and a later group of 409 women — 60 percent of whom had received at least one of the three shots in the HPV series — who visited the clinic from 2009 to 2010. Kahn and her team found that, overall, the percentage of women infected with one of the HPV vaccination strains decreased from 31 percent in the 2006-2007 group to 13.4 percent in the 2009-2010 group. 9.9 percent of vaccinated women in the latter group tested positive for HPV, and 15.4 percent of unvaccinated women also tested positive.

Though the study is definitely encouraging, doctors like Kahn say that herd immunity is still no reason for women to avoid getting vaccinated. The study also focused on a fairly small community of mostly African American women, so physicians caution people that further research is needed to confirm that herd immunity is really occurring in the broader population. According to Dr. William Schaffner (who must field William Shatner jokes all the time from annoying med students), the study highlights how the HPV vaccine is important not only for individuals looking to keep their private parts strong and healthy, but also for whole communities, which can fend off a disease if a growing segment of its members are inoculated against it. Still, the docs insist that everyone really ought to get vaccinated, just to be extra safe.