Tuesday, May 26, 2009

New and Hot: HPV Vaccination in Men?

Merck, the maker of the HPV vaccine Gardisil, is pushing for vaccination of young men. In December Merck asked the FDA to approve the vaccine for males ages 9 to 26, and last February the company presented the results of a male vaccination study to the CDC's Advisory Committee on Immunization Practices in the hopes that the CDC will endorse male vaccination in June. The study tested the vaccine in 4,000 men ages 16-23, and according to Merck, shows that the vaccine is about 90% effective in preventing infection from four types of HPV.

According to the CDC's HPV vaccine work group, the issue is cost-effectiveness. In women, the vaccine helps prevent cervical cancer, which threatens 10,000 Americans a year. For men, the vaccine would help prevent rarer diseases: penile and anal cancer. Because there is less of a direct benefit for males, at least part of the motivation for vaccination would have to be altruistic—vaccinating males could help prevent the spread of the virus to their sexual partners. As such, individual male patients might be unmotivated to shell out $300 for a vaccine that doesn't provide direct benefit.

It will be difficult to make a thorough cost-benefit analysis, as the prevalence of HPV infection in men is fairly uncertain. A literature review in The Journal of Infectious Diseases showed that various studies found a range of HPV prevalence between 1.3% and 72.9% (depending on kind of test, DNA and antibodies, and which part of the body samples were taken from). The chart below shows prevalence of HPV in men of various populations. It seems as if this range is so broad that it is practically useless. Furthermore, little is known about the rate of transmission.

-Elaine C

Journal of Natl Cancer Institute News Article
Washington Post Article
Literature Review

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