Should boys receive the human papillomavirus vaccine? Yes

Benefits of HPV vaccination

Two HPV vaccines are available: Gardasil targets HPV types 6, 11, 16, and 18 and Cervarix targets HPV types 16 and 18. Gardasil has US Food and Drug Administration approval for use in males (9-26 years), and HPV vaccines induce an equivalent immune response in boys and girls. Preliminary studies of Gardasil and Cervarix in boys reported ≥99% and 100% seroconversion respectively at seven months, and both vaccines were well tolerated.1 2 Comprehensive efficacy data are expected to confirm that the vaccine can prevent HPV infection and associated disease in boys.

HPV vaccines are designed to target HPV specific infections. HPV types 6, 11, 16, and 18 are prevalent in both cervical3 4 and non-cervical diseases,5 6 and the vaccines can prevent a range of HPV associated diseases. HPV types 16 and 18 contribute to 30% of vaginal, vulval, and oropharyngeal cancers, 20% of oral cancers, and 80% of anal cancers,5 6 and the incidence of these cancers is steadily increasing. A US study to assess the burden of HPV associated cancers in men and women found an average annual incidence of 24 918 cases, with most (56.5%) being non-cervical: 2.4% were vaginal, 9.1% vulval, 12.1% anal or rectal, and 29.5% oropharyngeal or oral cavity tumours.6 In addition, HPV types 6 and 11 cause genital warts, which are a common sexually transmitted disease with an estimated prevalence of 0.07-6.20/1000 women and 0.13-5.01/1000 men in the US.7 The primary objective of HPV vaccination should be to eradicate HPV infection, and this will be achieved only by a vaccination programme for both sexes.

Cost effectiveness

A US study evaluating the economic burden of non-cervical HPV disease calculated the overall medical costs to be about $418m (£248m; €280m), range $160m to $1.6bn.8 More than 60% of this financial burden was attributable to treating genital warts, with non-cervical malignancies accounting for $164.7m. Kim et al assessed the cost effectiveness of including boys in a routine HPV vaccination programme.9 Assuming 90% vaccine efficacy in males for HPV types 6, 11, 16, and 18 against all disease outcomes (cervical cancer, non-cervical malignancies, and genital warts) the ratio for a strategy including boys was $90 870 per quality adjusted life year (QALY), which is below $100 000 per QALY, the threshold for which an intervention is deemed a good economic investment in the US. If there was only 50% coverage in both sexes and lifelong vaccine efficacy against all disease outcomes, this ratio decreased to $62 070 per QALY.9

One evaluation in the UK identified that if HPV vaccine induced immunity is short lived (10 years), a vaccination schedule that targets only 12 year old girls would not be cost effective unless high coverage was achieved.10 Other studies have shown that vaccinating the whole sexually active population would be more cost effective even when prevention of cervical disease is the only disease outcome.11

Social inequity and psychological burden

Most cases of cervical cancer occur in low resource settings, and Castle and colleagues speculated that “targeting young women in these populations for HPV vaccination and screening older women would have a bigger effect on reducing the burden of cervical cancer than widespread HPV vaccination of young men from resource rich areas.”12 However, this assumes that funding for HPV vaccination and decisions about implementation come from a central source. In reality, although policies and strategies for vaccine implementation in low resource countries are influenced by the World Health Organization Expanded Programme of Immunisation, local governments hold the final decision, which is driven by economic realities.

Herd immunity obtained by vaccinating only women is likely to be insufficient to eradicate the targeted HPV types. In situations where vaccine uptake in females is expected to be low, it is more cost effective to vaccinate males than vaccinate hard to reach females.13 A single sex HPV vaccination programme may also increase the psychological burden on women,14 and this sex inequality could amount to an additional healthcare burden that could be avoided if the vaccine was administered to both sexes.

Lessons from history

In 1996, the rubella vaccine programme for women was extended to cover men after the disease reappeared in men.15 Rubella and HPV differ in many ways, including mode of transmission. However, the rubella scenario shows the potential pitfalls of a single sex vaccine programme. I advocate making HPV vaccination available to boys and girls in order to eradicate HPV infection and associated diseases in the population.