OPINION: Vaccination is one of the greatest public health success stories in history, shifting infectious diseases from the leading cause of childhood death and disease to a relatively rare cause of death in developed countries. Even globally, heart disease overtook infectious diseases as the leading cause of death in 2008.
But unless an infectious disease can be eradicated, high vaccination rates need to be maintained to control the disease. There are many historical examples of epidemics of previously rare diseases that have occurred when immunisation programs wane.
Australia, the United States and United Kingdom have different approaches to boost vaccination rates, with much overlap and similar success. But Australia is unique in using parental financial incentives for immunisation. From January, vaccine “conscientious objectors” will lose their childcare and family tax benefits, worth up to A$15,000 a year.
So, how do parents decide whether or not to vaccinate their children – and what works to increase vaccination rates?
How do parents decide?
Mass immunisation programs have developed in different ways around the world, and a range of factors are important to maintaining high levels of immunisation:
No vaccine is 100% safe nor 100% effective, so public health decisions about which vaccines to recommend and fund are made by weighing disease burden and cost against vaccine effectiveness, cost and safety.
Where consumers perceive a risk of infection to be high, the acceptance and demand tends to be high. Conversely, for rare diseases (often because of effective vaccine programs) or diseases perceived as less serious, consumers tend to focus more on risks of vaccination.
Delivery of vaccine programs, therefore, is a delicate partnership between immunisation providers and parents. Trust is critical to maintaining such programs.
The anti-vaccination lobby is a small but vocal group that has been around as long as vaccines have. They believe vaccines are unsafe and tend to associate compulsory vaccination with totalitarianism.
There is, however, a larger group of parents who delay or are hesitant about vaccination. This group is somewhat like swing voters – they are likely to be receptive to health promotion messages about immunisation, particularly from their doctor, but can equally be influenced by misinformation on the internet or false equivalence in the media.
Parental vaccine concerns are also influenced by vaccine side-effects or medical problems that coincidentally occur around the time of vaccines, and a host of factors that influence perceptions about the risks and benefits of vaccines.
A loss of confidence and trust by consumers can result in falling vaccination rates and epidemics. This was illustrated in the UK with measles outbreaks following the falsely attributed risk of autism following MMR vaccine.
How do you boost vaccination rates?
First, vaccines must be readily accessible to the public. This requires reducing or eliminating cost as a barrier and making the vaccine conveniently available. Strong support from health-care providers is central to gaining parental acceptance of vaccines.
Other strategies include financial incentives to physicians for achieving high vaccination rates among their patients (historically in Australia and the UK) and requiring vaccination to attend school (US and Australia) or to receive social benefits (Australia).
Australia has school entry legislation in most states except Western Australia and Queensland, which has “guidelines” for managing student immunisation data.
In the US, all states have school entry requirements that mandate immunisation prior to school entry. All states allow medical exemptions and 48 allow non-medical exemptions. West Virginia and Mississippi allow only medical exemptions.
Amid tremendous national attention surrounding a measles outbreak that originated in Disneyland, California, several states have proposed legislation to ban all non-medical exemptions.
There is certainly evidence that school-entry legislation raises vaccination rates. These are often accompanied by school exclusion policies for unvaccinated children during outbreaks. However, removal of vaccine legislation does not necessarily reduce vaccination rates, as seen in a region of Italy.
It has also been shown that ease of applying for conscientious objection to vaccination predicts lower vaccination rates, particularly if it is easier to gain an objection than to get immunised. The greater the administrative hurdles to applying for objection, the higher the vaccination rates.
Following major outbreaks of pertussis, four states (California, Oregon, Vermont and Washington) that had comparatively high rates of exemptions recently made their exemptions more difficult to obtain.
Addressing parental concerns
Recent suggestions to eliminate non-medical exemptions in the US and Australia are rooted in an understandable desire to reduce the risks of diseases and to equitably distribute the benefits and burdens of vaccination. But doing so may backfire.
Parents who feel they are being unduly coerced or punished to vaccinate their children are likely to become anti-vaccination. This coercion may push the hesitant parent in the exact opposite direction to what it is intended to achieve. Other members of the public may also feel sympathy for these parents.
Rarely, vaccination programs do go wrong, such as the first rotavirus vaccine rolled out in the US, which had to be withdrawn due to serious side effects. In a coercive environment, such incidents can derail vaccination programs.
But while a small proportion of Australians (<2%) are ideologically opposed to vaccines and are unlikely to change their minds, a larger proportion of vaccine-hesitant parents (about 4-5 %) may be responsive to efforts to boost vaccination.
If vaccination rates are falling, we need to understand why. We need to listen to and evaluate the concerns of parents and inform policy decisions with what we learn.
Health-care providers need tools and resources to talk with vaccine-hesitant parents. This ensures the credibility of the science as well as how it is communicated to and received by parents. Many such tools have been rigorously evaluated for effectiveness and have been used successfully.
Health-care providers also need to be adequately reimbursed for the time it takes to communicate with vaccine-hesitant parents.
Government systems that monitor the safety and effectiveness of vaccines and communicate the risks and benefits of vaccines can also be helpful. The US and some European countries (but not Australia) have no-fault vaccine compensation schemes to support their mandatory vaccination policies.
It may also be prudent to fund vaccine safety research if many parents are concerned about a particular issue, even if that level of concern is not shared by the scientific community.
There is evidence to support the effectiveness of mandatory vaccination strategies, but penalising parents who object on philosophical grounds may erode public confidence. Australia’s unique policy of linking financial benefits to vaccination poses an additional risk of backlash if these benefits are withdrawn from tax-paying vaccine refusers.
A more effective approach to boost vaccination rates is to increase the administrative hurdles to objection, but still allow it without penalty.
Raina MacIntyre is Professor of Infectious Diseases Epidemiology, Head of the School of Public Health and Community Medicine at UNSW.
Daniel Salmon is Associate Professor, School of Public Health, Global Disease Epidemiology and Control at Johns Hopkins University.
This opinion piece was first published in The Conversation.