The cost of giving boys the human papillomavirus (HPV) vaccine would outweigh any health benefit, researchers say.
A US Food and Drug Administration panel has recommended expanding use of the Gardasil vaccine to males aged nine to 26 to protect them from genital warts, but the cost effectiveness of such a programme was unclear at the time.
But researchers from the Harvard School of Public Health conducted such an analysis comparing a girls-only vaccination programme with a co-ed vaccination programme. Currently, Gardasil is approved for girls aged nine and over to protect them from cervical cancer.
"This study found that while vaccine coverage and efficacy are high in girls, including boys in an HPV vaccination programme generally exceeds what the US typically considers good value for money," said lead researcher Jane Kim, an assistant professor of health decision science.
The report is published in the British Medical Journal. Vaccination was considered a good value if cost-effectiveness ratios ranged from $50 000 to $100 000 per quality-adjusted life year, meaning the cost of the vaccine vs. the number of added years someone would gain by getting the vaccine.
Assuming 75% coverage and lifelong protection, the researchers found routine vaccination of 12-year-old girls was a good value at less than $50 000 per quality-adjusted life year. However, adding pre-adolescent boys increased the cost-effectiveness ratio to more than $100 000 per quality-adjusted life year.
The researchers considered treatment for conditions caused by HPV, including anogenital and oral cancers, genital warts, and juvenile-onset recurrent respiratory papillomatosis.
"Only under optimistic assumptions of high, lifelong vaccine efficacy against all HPV-related health conditions, or lower vaccine efficacy accompanied by lower coverage or vaccine costs, did vaccinating both girls and boys fall below $100 000 per quality-adjusted life year," Kim said.
Philip E. Castle, an investigator in the division of cancer epidemiology and genetics at the US National Cancer Institute and co-author of an accompanying journal editorial, agreed it is more cost effective to vaccinate just girls, rather than girls and boys.
Scientific reasons do exist to vaccinate boys, Castle said. "And from a social standpoint, people want gender equality, and those are fine things, but it is not a great investment to do that."
Debbie Saslow, director of breast and gynaecologic cancer at the American Cancer Society, also agreed with the findings.
"If we can vaccinate a high enough proportion of young girls, then vaccinating boys is not cost-effective," she said.
Other experts disagreed.
More date needed before a decision can be made
Anna R. Giuliano, chair of the department of cancer epidemiology and genetics at the H. Lee Moffitt Cancer Centre and Research Institute in Tampa, Fla., said more data is needed to decide the issue appropriately.
"Some of the assumptions in the study, such as low HPV attributable risk for male cancers, and the very optimistic scenario of 75% vaccine dissemination in both females and males in the US may have led to the relatively unfavourable cost estimates provided for male vaccination in this publication," she said.
She said the study also failed to consider the reduction in the burden of male diseases if boys were vaccinated. "This is an important public health estimate, and one that is meaningful for making public policy and clinical recommendations," she said.
Dr Erich M. Sturgis, an associate professor of head and neck surgery at the University of Texas MD Anderson Cancer Centre in Houston, thinks Kim's group has underestimated the number of head and neck cancers attributable to HPV infection.
"We see these patients suffering every day with the treatment, and patients dying of this disease," Sturgis said. "I think the proportion of oropharyngeal cancers that are attributable to HPV is a clear underestimate in the study."
’Data at odds with study numbers’
The Harvard team attributes about 30% of these cancers to HPV, but the latest data shows it's really 60% to 70%, he said.
"If it's cost effective to vaccinate girls against cervical cancer in the United States, I think it would be cost-effective to vaccinate boys to prevent oropharyngeal, pineal and anal cancer," he said.
Merck & Co., maker of Gardasil, has petitioned the FDA to approve the vaccine for boys to prevent genital warts. Jennifer Allen, a Merck spokeswoman, said the company's data is at odds with the study numbers.
"The Merck health economic analysis shows that vaccinating males with Gardasil is cost effective at a per quality-adjusted life year of less than $25 000," Allen said.
"Our model is based on data from our clinical trials, as well as data we gathered after the approval of Gardasil," she said.
Gardasil, approved for girls in 2006, covers four types of HPV, two of which cause about 70% of cervical cancers worldwide.
Since Gardasil's approval, studies have found it safe and nearly 100% effective in preventing precancerous cervical lesions from the four HPV strains targeted by the vaccine.
Studies have also found that Gardasil far more effective when given to girls or young women before they become sexually active. – (HealthDay News, October 2009)
HPV vaccine for boys?