HPV Vaccination: Three doses may not be needed
Thursday, October 15, 2015
Data from two large clinical trials provide additional evidence that one or two rounds of commercially available human papillomavirus (HPV) vaccines induce protection comparable to that of the recommended three-dose regimen. Kevin Holcomb, M.D., associate professor of clinical obstetrics and gynecology, was invited by Clinical Oncology News to comment on a recent Lancet Oncology study. Read the full article here.
Cervical cancer remains the second most common cause of cancer-related death in women worldwide, with the majority of these deaths occurring in developing nations. Persistent infection with oncogenic HPV is the etiologic agent for cervical cancer, with 70% of cases attributed to HPV types 16 and 18. The proven efficacy of prophylactic vaccination of young women with HPV virus–like particles (VLP) to prevent primary HPV infection has offered a paradigm shift from early detection with screening to cancer prevention through vaccination. The potential effect of this breakthrough, however, is limited in low-resource settings due to cost constraints.
The current study combined data from two randomized controlled trials of prophylactic vaccination with a bivalent HPV-16/18 VLP vaccine to determine the efficacy of fewer than the three recommended doses of vaccine. The results suggest that the prevention of HPV-16/18 infection was similar in women and girls who received three, two and one dose(s) of the vaccine. Cross-protection against closely related HPV types was also seen in a subset of participants receiving two doses of vaccine at a six-month interval. The main limitation of the study is its nonrandomized design, which introduces the potential for bias. The primary end point of one-time infection with HPV-16/18 also is not accepted as a surrogate for HPV-related disease. Nonetheless, the results suggest that the bivalent HPV vaccine may be effectively used with fewer doses and significantly reduced cost. Hopefully, this study brings us one step closer to worldwide introduction of HPV vaccination for the prevention of cervical cancer.