Merck's Gardasil protects against strains not in vax

Two new studies to be published in the April 1 issue of Journal of Infectious Diseases say Merck's quadrivalent human papillomavirus vaccine, Gardasil, appears to protect against viral strains not included in the vax. This is especially the case for women not exposed to the virus before vaccination, American Medical News reports.

The analysis were based on data on 17,622 women, aged 16 to 26, taking part in Phase III studies for Gardasil. One study showed that Gardasil reduced the risk of precancerous changes in cervical cell growth caused by 10 strains not included in the vaccine in women unexposed to the virus. The second paper reports that when both the exposed and unexposed groups were analyzed together, the risk was cut by 15.1 percent.

Study authors say it's not completely clear why Gardasil protects against strains not included in the vaccine and questions still remain about the duration of immunity. "There are families of related HPV types, and we think the antibodies made when women are vaccinated have an effect against other closely related viral types," said Dr. Brown, the lead author on the first paper and a co-author on the second.

- check out the AMNews article for more