Diana mentioned in her last post that the HPV vaccine is now recommended as a routine vaccine for males and females. In addition, the findings of a four-year study have shown the effectiveness of the HPV vaccine, demonstrating that it prevented 90% of genital warts in males who had no prior exposure to the HPV strains present in the tetravalent vaccine, and that it prevented 66% of genital warts in males who had prior exposure to the strains in the vaccine. In addition, in males with no previous exposure, the vaccine prevented persistent infection in 86%. The findings of this study are the first to show that the HPV vaccine is effective in males.
The study took place in the United States, Australia, Canada, Brazil, Mexico, Taiwan, Norway, and Peru. A total of 18 countries and 71 sites were concluded. 4,065 men participated and all had no prior incidence of warts or lesions in the genital or anal areas. Males ages 16-26 participated, 85% of which had only female sexual partners and 15% of which had male sexual partners. The study was randomized so that men would either be part of the control group, which received a placebo, or the experimental group, which received the HPV vaccine with strains 6, 11, 16, and 18. After receiving either the placebo or vaccine, men underwent six examinations over a time period of three years to see whether or not the vaccine had been effective.
The findings are important because they demonstrate that the tetravalent HPV vaccine can be used to prevent genital warts in men, a disease that, according to the article, can cause "depression, social stigma, and loss of self-esteem". In addition, reducing male risk of HIV also prevents the chance of passing HPV to other males and to females during sexual activity. Further research needs to be done to determine if the vaccine can also have prophylactic benefits on males' risk of anal, throat, and genital cancers.
It is interesting to note that Merck, the producers of the vaccine, sponsored the study. However, because it was double-blinded and results were published in NEJM, this conflict of interests doesn't look too suspicious.