Just 2 doses of a vaccine against human papillomavirus (HPV) strains that can cause cervical cancer may provide protection similar to that of the recommended 3-dose regimen, suggest results of a clinical trial in Costa Rica.
The investigators analyzed data from 5967 women who received 3 doses of Cervarix (which protects against HPV types 16 and 18) or a control vaccine, 802 who received 2 doses of either vaccine, and 384 women who received only 1 dose of either vaccine (Kreimer AR, et al. J Natl Cancer Inst. 2011;103:1-8). When they compared the 4-year incidence of HPV 16 or 18 infections in each group, they found similar levels of protection against infection with HPV 16 or 18 in the women receiving either 2 (84.1% efficacy) or 3 (80.9% efficacy) doses of the HPV vaccine. No infections were detected among women in the 1-dose group, but the authors acknowledge that this may be a consequence of the small number of women in this group.
Kuehn BM. Two Doses of HPV Vaccine May Be Sufficient. JAMA. 2011;306(15):1643. doi:10.1001/jama.2011.1480