Limitations With Herd Immunity From Vaccine-Type Human Papillomavirus
No consistent set of modifiable risk factors was shown to be associated with vaccine-type HPV infection following vaccine introduction.
According to the results of a study published in the Journal of Pediatric & Adolescent Gynecology, no consistent set of modifiable risk factors was shown to be associated with vaccine-type human papillomavirus (HPV) infection following vaccine introduction.
Researchers evaluated vaccine-type HPV infection in 1180 young women (age 13-26 years) from a hospital-based teen health center and a community health department and determined risk factors for infection among unvaccinated women. Infection was assessed in 3 cross-sectional studies between 2006 and 2014: wave 1 (2006-2007; before vaccine introduction), wave 2 (2009-2010), and wave 3 (2013-2014).
The highest rate of unvaccinated women was in wave 1 (100%), and the lowest rate was in wave 3 (28.5%). In wave 3, vaccine-type HPV infection was reported for 18.8% of unvaccinated women compared with 3.2% of vaccinated women.
In wave 1, multivariable logistic regression revealed that vaccine-type HPV infection was associated with a history of anal intercourse (odds ratio [OR] 1.8; 95% CI, 1.1-3.0), age 18 to 21 years compared with age 13 to 17 years (OR 2.1; 95% CI, 1.2-3.6), and black or multiracial race compared with white race (OR 1.8; 95% CI, 1.1-3.0).
No risk factors were associated with HPV infection in wave 2. In wave 3, HPV infection was associated with a history of sexually transmitted infection (OR 3.6; 95% CI, 1.3-9.7).
The study authors concluded that the results, “underscore the urgency of public health efforts to promote vaccination for primary HPV prevention and the limitations of relying on herd protection.”
Smith C, Ding L, Gorbach PM, Franco EL, Kahn JA. Who's not protected in the herd? Factors associated with vaccine-type HPV in unvaccinated women [published online September 21, 2017]. J Pediatr Adolesc Gynecol. doi: 10.1016/j.jpag.2017.09.008