Data from a clinical trial of Gardasil® in male subjects revealed that Gardasil® is effective at preventing changes in anal cells as a result of chronic human papillomavirus (HPV) infection.5 Data from clinical trials on Gardasil®9 showed close to 100% efficacy in preventing infections of the cervix, vulvar, and vaginal tract in addition to preventing pre-cancerous conditions. The types of HPV infections prevented by Gardasil®9 include seven types of HPV genotypes, including HPV 16, 18, 31, 33, 45, 52, and 58.
A reasonable question raised here concerns the efficacy of the 2cHPV and 4vHPV vaccines that cover only a fraction of HPV targets. It turns out that a unique immune response phenomenon called cross-protection plays an important role in generating a wider range of protection. Specifically, female subjects who received three doses of the 2vHPV vaccination that covers HPV 16 and 18 only were found to have mounted immune protection against new infections caused by three genotypes of HPV 31, 33, and 45.
Based on data collected so far, Cervarix confers protection for up to 11 years, Gardasil® for 10 years, and Gardasil®9 for at least 6 years. These long-term studies are ongoing, and updated data are still unfolding.
