1 Dose of HPV Vaccine May Offer Protection: Study

Two large international trials suggest single immunization may be as good as two or three

By Robert Preidt

Wednesday, June 10, 2015

WEDNESDAY, June 10, 2015 (HealthDay News) -- One dose of the human papillomavirus (HPV) vaccine Cervarix could prevent as many cases of cervical cancer as the current two- and three-dose schedules, a new study contends.

The vaccine protects against HPV types 16 and 18, which are believed to cause about 70 percent of cervical cancers. The vaccine was originally approved to be given in three doses over six months, but many countries are switching to a two-dose schedule in teenagers. The U.S. Centers for Disease Control and Prevention still recommends three doses for young Americans.

Researchers conducted two large phase 3 clinical trials that included more than 26,000 women between the ages of 15 and 25. They lived in North America, Latin America, Europe and Asia.

The researchers found that one dose of Cervarix offered similar levels of protection over four years when compared to two and three doses.

The findings were published online June 9 in The Lancet Oncology. Cervarix maker GlaxoSmithKline provided funding for one of the studies.

"Our findings question the number of HPV vaccine doses truly needed to protect the majority of women against cervical cancer, and suggest that a one-dose schedule should be further evaluated," co-study author Aimee Kreimer, of the U.S. National Cancer Institute, said in a journal news release.

"If one dose is sufficient, it could reduce vaccination and administration costs, as well as improve uptake. This is especially important in less developed regions of the world where more than 80 percent of cervical cancer cases occur," she explained.

However, further research is needed before vaccination guidelines can be changed, according to co-lead study author Cosette Wheeler, of the University of New Mexico Health Sciences Center in Albuquerque. She said researchers need to conduct trials lasting longer than four years to see how long the protection from one dose lasts.

But the idea of a one-dose vaccine is certainly a welcome one, experts said.

"If HPV vaccines could be delivered as one dose, while retaining their efficacy [effectiveness] against the most oncogenic HPV types 16 and 18, the global burden of cervical cancer would substantially decrease," Dr. Julia Brotherton, of the Victorian Cytology Service Registries in Melbourne, Australia, said in the news release.

Cervical cancer is the fourth most common cancer in women worldwide, according to the researchers.

SOURCE: The Lancet Oncology, news release, June 9, 2015

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