Ladies First - and Only - For HPV Shot?

HPV prevention most effective through vaccination of one sex in mathematical models

(RxWiki News) Parents and policymakers confounded by the best practices for reducing HPV transmission could look to mathematical models to determine a good vaccination strategy for the sexually transmitted infection.

A study this week determined that a vaccination campaign that focuses primarily on immunizing females is most effective at preventing the HPV, or human papillomavirus, an infection that can lead to cervical cancer when undetected and untreated.

"Be sure all family members are up to date on their recommended immunizations."

Johannes Bogaards of VU University Medical Centre in Amsterdam led a team of researchers in developing mathematical models to determine the best methods for reducing HPV transmission rates.

They developed a variety of simple scenarios in which HPV was transmitted among both sexes, made predictions from that data, and then ran more complex models to test those predictions.

They found that in nearly every plausible circumstance, the best strategy for reducing HPV infections is to vaccinate just females, the sex with the highest rate of infections.

According to the study, "Once routine vaccination of one sex is in place, increasing the coverage in that sex is much more effective in bolstering herd immunity than switching to a policy that includes both sexes."

Herd immunity is a term used in public health to mean that passing along an infection becomes less likely when enough people are vaccinated that the infection cannot travel within or throughout the population.

Not all experts in vaccines, however, are convinced that this study should impact policy. Speaking with dailyRx, Dr. Paul Offit, chief of the Division of Infectious Diseases and director of the Vaccine Education Center at the Children's Hospital of Philadelphia, said the study ignores one major population and does not consider other reasons for vaccinating both sexes.

"You are ignoring one of the biggest risk groups, men who have sex with men," said Offit, who invented the rotavirus vaccine and has authored several books about vaccines.

"They are at especially at high risk of having genital and anal cancers associated with HPV." He said people may not realize that cervical cancer is not the only kind of cancer caused by HPV.

Offit said there are three "compelling reasons" to give boys the HPV vaccination in addition to girls. First, each year 2,000 to 3,000 males get anal, genital and head and neck cancer caused by HPV, he said.

"Second, boys get anal and genital warts from HPV, which is disfiguring and emotionally crippling," he said. "And third, girls still get HPV from boys."

He points out that a previous vaccination effort with hepatitis B that targeted only the high risk populations was not successful in significantly reducing hepatitis B cases until the vaccination campaign was expanded to include all newborn babies in 1991.

Parents should continue to follow the recommendations of the Center for Disease Control in determining which immunizations to give their children. The findings from this study may be taken into consideration for public health officials and policymakers trying to design vaccination campaigns to reduce HPV infections.

The article appears in this week's Public Library of Science Medicine journal. The study was funded by the Health Research and Development Council of the Netherlands Organization for Scientific Research.

Two researchers have received unrestricted research grants from the pharmaceutical company Glaxo Smith Kline (GSK), one acted as a research consultant for Sanofi Pasteur MSD (Merck), and one acted as a research consultant for Sanofi Pasteur MSD and GSK.

Review Date: 
December 20, 2011