Should HPV vaccination programs be expanded to boys?
Vaccination programs are based on the old adage that an ounce of prevention is worth a pound of cure. Since 2007 Canada has had a vaccination program for the Human Papillomavirus (HPV) administered to girls, although the age of vaccination varies by province: Grade 5 in Alberta and Grade 8 (with catch up until Grade 12 for those not previously vaccinated) in Ontario.
Now many provinces are wrestling with the decision about whether to expand the program to also vaccinate boys.
HPV and cancer
HPV is one of the most common sexually transmitted infections, according to the Public Health Agency of Canada. It is estimated that more than 75% of Canadians will have at least one HPV infection in their lifetime. HPV causes non-genital and genital warts as well as cancers of the cervix, oropharynx (mouth and throat), anus, penis and vulva.
The strongest association between HPV infection and cancer exists for cervical cancer. Two types of HPV (16 and 18) are responsible for approximately 70% of cervical cancers. Every year in Ontario more than 600 women are diagnosed with cervical cancer and 150 women die from the disease.
There are now vaccines for HPV that reduce the rates of persistent infection leading to cervical cancer, and it is this benefit that led to the 2007 roll out of vaccination programs across Canada.
Why immunize boys?
Recently, pressure has begun to mount for governments to cover the HPV vaccine for boys. This move is supported by a statement from the National Advisory Committee on Immunization (NACI), recommending that there is good evidence for the use of the vaccine for boys and men age 9 to 26 years. NACI goes on to say that governments should consider a range of factors when deciding whether to add males to the female-only vaccination programs.
There are two primary reasons to consider expansion of the program.
The first is that herd immunity (the level of immunization reached that results in overall population protection even for those who are not immunized) is dependent on achieving a certain rate of vaccination of girls. The programs are designed with a 90% target for vaccinations, and while rising, the current rates are around 70% in Ontario and 61% in Alberta. Since these rates do not reach the target needed to achieve herd immunity, vaccinating boys could have additional benefit.
Dr. Shelley Deeks, Medical Director, Immunization and Vaccine-Preventable Diseases at Public Health Ontario, points out that while 90% is the target, the programs are still effective at lower rates. “There is emerging evidence that with 70% immunizations rates for girls, the programs in the US and Australia are already achieving herd immunity as shown by a dramatic decline in genital warts” she says.
The second is the concern that a high-risk subgroup, men who have sex with men, receive limited benefit from the current program. This population is at risk for less common cancers, including throat, anal and penile cancers that may be related to HPV infection.
“They are mostly excluded from the benefit of herd immunity created by the female based vaccination programs” says Deeks. Since the vaccine’s potential is expected to be greatest when administered before an adolescent becomes sexually active, “it difficult to protect this population without a policy of broad vaccination of all male adolescents since young men are unlikely to self-identify prior to sexual onset”.
Not an inexpensive decision
Despite the above two reasons and the NACI recommendations, covering boys with HPV vaccine is not a straightforward decision. A full course of the vaccine costs between $450 and $500 in Canada. This cost was initially offset by a one time, five-year federal government investment of $300 million dollars to get the initiative underway.
Models developed using demographic and disease prevalence data showed it is far more cost effective to reduce the incidence of cervical cancer through a mass vaccination program that targets girls. The models look at the impact of immunization on the rates of cervical cancer. The models shows that while immunizing girls has a significant impact on cervical cancer rates, with a 63% reduction, doubling costs by immunizing boys only achieves a further reduction of 4% in cancer rates.
However, the models are based on the assumption that 90% of girls are immunized, lower than Ontario’s vaccination rate of 71%. Deeks argues that since the cost effectiveness of vaccinating boys isn’t as well established as it is for girls, perhaps programs should focus on trying to “increase the vaccination rates of girls before adding boys.”
The findings of a cost effectiveness analysis published in the British Medical Journal in 2009 show that the estimated cost-effectiveness of vaccine programs targeting girls to reduce cervical cancer rates is around $50,000 per quality-adjusted life-year gained (QALY). In contrast, conservative estimates of adding boys to the mix is said to cost approximately $300,000 per QALY gained.
Such variation in the cost-benefit of preventive measures is not unique to this vaccination program. A landmark American study published in 1995 reviewed 500 different ‘life-saving’ interventions and found major differences in cost effectiveness, ranging from $40 for an exercise stress test to detect heart disease to $34 billion for screening newborns for sickle cell disease.
The ethics of considering cost
All health care systems ration services. Some ration by income, some ration by need. Some jurisdictions have chosen to set thresholds for funding new treatments. For example, the UK has set a ceiling price that marks the top price that they are willing to pay, and it is measured by the cost to buy one quality-adjusted life-year. These thresholds for cost effectiveness alone predict the nature of 82% of the funding recommendations made by the National Institute for Health and Care Excellence in the UK.
Thresholds provide more clarity and transparency about what governments will fund since they are upfront about limits on one hand, but at the same time, they do allow limited flexibility in buying some very expensive interventions. Some argue that pricing strategies for pharmaceutical companies respond to thresholds, therefore helping to keep costs lower. However, others argue that thresholds can drive the costs of certain cheaper drugs higher because companies price their treatment to meet the ceiling for payment.
In Canada, we don’t set explicit thresholds, “Thresholds dichotomize a scale into cost-effective versus not,” says Dr. Murray Krahn the Director of the Toronto Health Economics and Technology Assessment Collaborative. “You must have a scale that has some meaning to it, but refusing to commit to an explicit threshold means that we are implicitly adopting a kind of continuous cost-effectiveness scale.”
Krahn explains that cost effectiveness is one attribute among others being considered in a decision-making framework. “Cost effectiveness tells you whether or not you are getting a good deal, or perhaps spending too much, but that is just one dimension” he says.
Decision making… beyond cost
While considerations of cost and the related ethical issues are certainly important, Krahn says there is also broad agreement that health policy decision making in Canada’s publicly-funded health care system are as much driven by other considerations as by economic estimations of value for money.
Other societal factors that might be weighed include: “vaccine fear”; feminist concerns (such as whether or not it is equitable for women to bear the full responsibility for the consequences of sex); the health needs of the gay community; the policy principle of gender neutrality and perceptions about the role of the pharmaceutical industry.
Krahn maintains that cost should be just one of three considerations when making resource allocation decisions in health care. He says “first, there is consideration of the evidence that vaccinating boys improves health outcomes for anyone, and whether it is safe. The second question is, whether it’s cost effective. If you are spending some money, the denominator will be how much benefit will that additional spend provide? The third consideration is how does society feel about this decision?”
Prospects for expanding the HPV vaccine to boys
It is perhaps due to these many other factors that, despite the hefty cost of adding boys to the program, Alberta and PEI have chosen to expand their coverage of HPV vaccination to boys and most other provinces are finding themselves under pressure to consider it.
HPV vaccination illustrates the complexity of decision making regarding the public coverage of interventions in health care. Decisions regarding the type of vaccination program to offer are value laden, heavy with controversy and require complicated choices. This debate helps to demonstrate the need for discussion that brings greater transparency to the conflicts that arise between the concepts of individual patient rights, public and political views, and evidence-based decisions on where to best spend public dollars.