Immunity is a “game of numbers,” said Dr. Tim Lahey, a professor at the Dartmouth Institute for Health Policy and Clinical Practice, in which the “way to win is to get as many people as possible immunized so that it just disappears from the population.”
So how do governments encourage people to win the numbers game?
Human motivation is a tricky business. No one ever wants to be frightened into action, and even less do we want to be muscled into doing something — even if that something is the “right thing to do.”
Why governments encourage vaccination
Immunity from disease develops as a result of sickness or vaccines, which are killed or weakened versions of the disease that spur our immune systems to produce a defense against the real thing.
Yet there’s a hitch when it comes to vaccines.
“Most vaccines are partially protective but not fully protective,” Lahey said.
For this reason, if you look at some of US outbreaks of measles or mumps — which at least 90% of the population has been vaccinated against since 2000 — the people who get sick are usually those who have not been immunized. Still, even some people who have been vaccinated have become sick during an outbreak.
So if measles “immunization rates fall to, say, 50% to 60%, and we might say, ‘Heck, that’s not so bad,’ ” Lahey said, that still would mean that “probably 60% to 70% of people are vulnerable” to a life-threatening illness.
Medical experts say that between 92% and 95% of children should receive two doses of the measles, mumps and rubella (MMR) vaccine to maintain herd immunity, in which the entire group is protected because most individuals are. Even a highly infectious disease like measles simply cannot spread when herd immunity has been achieved.
But how do nations attain that high level? Naturally, the answers vary around the globe.
By far, though, the nations hardest-hit by measles infections in Europe are Italy and Romania.
As of May 30, Italy has reported 2,719 cases in 18 regions since the beginning of 2017, according to a report from the European Centre for Disease Prevention and Control. The majority of measles cases, 89%, were among people who were not vaccinated, while 6% of measles infections affected people who received only one dose of vaccine. The same report indicates that 6,434 cases, including at least 26 deaths, occurred in Romania between January 1, 2016, and May 26, 2017.
Italy, then, is essentially following the lead of the United States, which requires vaccination for school attendance. The Italian requirements, though, incorporate a few twists. Going forward, parents will provide proof of vaccination when enrolling their children in government-run nurseries or preschools, just as is done in the United States. But in Italy, the parents of children who have not been vaccinated will be fined. Conscientious objection, unlike in the United States, will not be allowed.
“Every European country is different,” Larson said. “Each have their own immunization schedule, which can differ between countries.”
Generally, though, European nations tend to prefer voluntary vaccination to mandates, Larson said.
Though overall sentiment toward vaccinations is positive, the research team found wide variability between countries and across regions.
“Vaccine-safety related sentiment is particularly negative in the European region,” Larson and her colleagues noted in their report. “Countries with high levels of schooling and good access to health services are associated with lower rates of positive sentiment, pointing to an emerging inverse relationship between vaccine sentiments and socio-economic status.”
“I think the main point is that while there is overall good vaccine acceptance in Europe, there are clear trends reflecting more questioning about vaccines,” Larson said.
Typically, this school mandate “does increase the likelihood that children get immunized,” said Lahey, who sees the requirement not as a punishment but “as a carrot encouraging a carrot,” since both vaccination and school are positives people want for their children.
Yet some parents feel that their children ought to have the right to attend school “without accepting responsibility for the implications of doing that,” he said. Part of that responsibility is making sure school is a safe place. “And one way to make sure you’re safe is to not be contagious, and vaccines really help that,” Lahey said.
Still, he acknowledges that “sometimes in the conversation around vaccines, people can react against the incentive” and “develop resentments.” “They can feel like being encouraged to get immunizations gives them a loss of control,” he said. So while some parents opt out of vaccinating their kids, other people simply slip through the cracks.
Ultimately, then, there’s always a minority group that may not be vaccinated for one reason or another, Lahey said.
If this unvaccinated minority remains small, herd immunity can still be effective. A problem arises when the minority begins to grow.
Noel T. Brewer, a professor of health behavior at the Gillings School of Global Public Health at the University of North Carolina, sees people as falling into three camps.
There are those who understand and want vaccines and will go out of their way to get them, while in the opposite camp are those who do not want vaccines and “may even be activists,” he said. And then there’s the “great middle: that large number of parents who are not likely to take action one way or another unless someone prompts them to.”
Reaching those folks in the middle is key. So to increase vaccination rates, Brewer sees three possible approaches. “There are parents, there are providers, and then there are the systems, and we can try to address each of these in different ways.”
Yet directly reaching out to parents has not been “all that effective. So promotional campaigns don’t seem to do a lot,” Brewer said. Although social media seems to have a “fairly large influence” on what people talk about these days, “it’s unclear whether interventions through social media have much of an effect.”
According to Lahey, emerging data indicate that if someone in your social circle — whether that’s a person at your tennis club or your minister — puts vaccination forward as “a social norm, that does seem to encourage people to be more likely to get vaccination.”
Meanwhile, health care providers — whether doctors, nurses or physician assistants — are spending more time than in the past talking about this issue with patients, Brewer said.
“We don’t have evidence of that, but that’s what we hear,” he said. “The question is, how do we help physicians solve that?” From his research, the first step is clear.
“Most parents just want to know that (vaccination) is something a provider recommends,” Brewer said, explaining how he and his colleagues created “the announce approach, where physicians start off with just announcing a child is due — a presumptive announcement.”
Another piece is “a systems piece, and that could be everything from how the provider sets up appointments all the way up to the laws that govern vaccination,” Brewer said. In between are immunization information systems in every state that share information across providers.
At the systems level, though, there are problems, he said.
State immunization registries are often incomplete or have very out-of-date information, he said. So while it’s been shown effective to send reminder notices to parents based on data in the state registries, the record-keeping issues make this difficult. Also, some vaccines require parents to come back after six to 12 month, bur appointment systems don’t go out that far.
With a variety of technology systems across doctors’ offices, schools and governments, “interoperability” — whether one system can talk to another — “is not that well-established yet,” Brewer said.
In addition, providers often must write something down to go home with the parent and then enter the same information into a patient’s electronic record and send a notice to both the state immunization registry and a school.
“The keeping track of who’s got what vaccines is really burdensome,” Brewer said. Although large clinics have the ability to build in additional administrative layers to handle or even automate this, smaller ones do not.
Meanwhile, in the zone between providers and systems are health insurance companies, which also have an interest in maintaining high vaccination rates and herd immunity.
“Immunization among all populations in the United States is one of the most cost-effective means of preventing disease,” said Cathryn Donaldson, director of communications and public affairs for America’s Health Insurance Plans, an industry organization for health insurance companies.
To boost vaccination rates, some health insurance companies offer financial incentives to doctors and other providers. While some research studies show positive effects in increasing vaccination rates, others show “not much of an effect,” according to Brewer. “It’s almost surprising. It should have an effect.”
“Firstly, patients in lower earning scales get some additional family tax rebates if they have kept their child up-to-date with their various vaccinations,” said Dr. Tony Bartone, vice president of the Australian Medical Association. Since No Jab, No Pay began in January 2016, more than 210,000 families have taken action to ensure that they meet the immunization requirements, according to Australia’s Department of Social Services.
Like the United States, Australia mandates that child-care centers and preschool facilities can permit only children with up-to-date immunizations to attend, Bartone said.
“Doctors many years ago were incentivised through a grant based loosely on pay for performance. This was very successful in that previously very good levels were almost converted to exceptionally high levels ( >95%),” Bartone wrote in an email. The grants also led to “upskilling” for nurses, allowing them to learn how to administer vaccines.
While the program eventually “fell victim to budgetary cuts,” Bartone noted, these human resource improvements have remained and continue to benefit the Australian population.
“However there is a small proportion, roughly 1-2%, which refuse still to vaccinate, often misled by information on websites or various active lobby groups,” he said. The problem occurs because unvaccinated people tend to cluster in certain locations. This can decrease vaccination rates in some locations to below the necessary herd immunity percentage.
“This will/could allow pockets where the infection can grab a foot hold and even lead to small regional epidemics,” Bartone said. With global movements and transportation, even larger-scale outbreaks may occur.
Some, including Julie Leask, an associate professor in the School of Public Health at University of Sydney, suggest that the “No Jab, No Pay” policy has some unintended consequences.
By “shutting out the children of vaccine objectors,” a low-quality child-care market may be growing in support of the families who forfeit benefits to uphold their anti-vaccination beliefs, Leask said.
In Canada, about 85% of children are completely vaccinated, while fewer than 2% of parents are strongly opposed to vaccination, wrote Ève Dubé of the public health institute in Quebec in an email. “The remaining proportion are children who are missing 1-2 doses or 1-2 vaccines.” Canada lacks a national immunization registry and wide variation exists across provinces, so Dubé noted the nation’s vaccination rates may be underestimates.
“Not all missing doses are due to parents’ vaccine hesitancy — some can be related to lack of access to vaccination services,” Dubé wrote. “Traditionally, most of the interventions to increase vaccination rates were aimed at enhancing access to vaccination services (reducing distance to vaccination clinics, offering vaccination during home visit, sending reminders, etc.).”
Other interventions — such as offering vaccines during routine well-baby clinics instead of requiring an extra appointment — are pretty effective as well, Dubé said.
“The effectiveness of education/information campaigns are much lower,” she said. Although these campaigns do support the pro-vaccine decisions made by most parents, they are “not sufficient to sway vaccine-hesitant views.”
Imposing financial penalties for vaccine refusal, such as Australia’s “No Jab, No Pay” policy, do not exist in Canada and would be legislatively complicated to put in place, according to Dubé.
Yet Dubé is skeptical when it comes to using similar methods to change the behavior of those who oppose vaccines. Such policies “could certainly be effective” in moving parents who simply forgot to make an appointment to vaccinate their children, but “no sanction or policies will change the mind of those strongly opposed to vaccination.” And this is a problem.
Even though herd immunity will protect the 2% to 3% of unvaccinated people if they remain within the broader community, “the problem is that these under-vaccinated people tend to cluster together,” Dubé said, echoing Bartone’s thoughts.
“It has taken massive investments over many generations to achieve herd immunity to vaccine-preventable diseases. Its loss threatens the cumulative value of all those efforts,” Dubé said. “Childhood vaccination is a thorny issue. … While scientific consensus on the public health benefits of vaccination is unequivocal, there is no such agreement on how best to respond to vaccine hesitancy and refusal.”
Despite spots of bad news, the overall picture is positive, Brewer inssisted. “Let’s think about the commonness of it. Vaccination uptake is very high. For childhood vaccines, it could be over 90%. There are very few other health behaviors we can point to where we have such success,” he said.
“We don’t see measles, mumps, rubella, polio so much anymore, so we don’t feel like we’re at risk and therefore the inconvenience, the cost, the very small risk of immunizations can feel like the bigger problem,” he said. If you were to talk to people in places where these diseases are endemic, “They just would look at some of the people engaged in our debates and shake their heads like, ‘What are you thinking?’ “