Science

Why (some) parents don’t vaccinate

Jun 14, 2016 /
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The many-headed dragon of public anger has a mouthful of fire for parents who don’t vaccinate. But such scolding misses the mark, alienating caring parents who just want their kids to be safe.

When measles broke out at California’s Disneyland in 2015, sickening nearly 150 people across seven states and spreading to Mexico and Canada, the online backlash against non-vaccinating parents was swift and unforgiving. Parents were accused of neglect, and some went as far as to say they should be prosecuted. Elsewhere they were denounced as “selfish” and “stupid.” Tara Haelle says those characterizations are not only wrong, they are damaging.

Haelle [TEDx Talk: Why Parents Fear Vaccines] knows firsthand how it feels to be too afraid to vaccinate your child. When her first son was born, she, too, turned down a vaccine. Unsure what the risks might be for a newborn, and feeling that she hadn’t done enough research, she declined to vaccinate for hepatitis B until reluctantly agreeing to the shot two months later. “I wasn’t dumb or stupid — I was actually in grad school,” she recalls. “But I was scared, just like hundreds of other parents I’d spoken to in the six years I’ve been reporting on this issue.”

Now a science and health journalist, and the co-author of The Informed Parent: A Science-Based Resource to Your Child’s First Four Years (along with Dr. Emily Willingham), Haelle says it’s important that we change the way we communicate about vaccine hesitancy, and start responding with empathy to those parents who are “utterly terrified of doing the wrong thing — of harming their child when all they want to do is protect them.” Vitriolic and accusatory attacks are counterproductive, widening the divide between those who vaccinate confidently, and those with concerns, she says. “If we’re going to address vaccine hesitancy, we have to address the underlying processes that lead people to believe in fears lacking any scientific basis.”

The problem with success. Vaccination is overwhelmingly the norm. The national median for the measles-mumps-rubella vaccine (MMR) is around 94 percent in kindergartners, and most parents wouldn’t hesitate to get their kids vaccinated. Nationally, less than 2 percent of children entering kindergarten were exempt from vaccinations in 2014. But the Disneyland outbreak highlighted a critical problem that’s occurring across the US: pockets in the overall population where parents are choosing not to vaccinate their children, where vaccination rates have dropped to worrying levels.

“We now find ourselves in a century when we can beat back more than two dozen diseases that once killed millions, and one of the biggest threats to public health is not the diseases themselves, but vaccine hesitancy — the fear that holds parent back from vaccinating their children,” says Haelle.

While small, these pockets create points of weakness in an otherwise powerful nationwide armor against preventable disease.

“Vaccines work in two ways,” Haelle explains. The first is inside the body, the second is outside. “In an individual, the body makes antibodies in response to the vaccine against the disease. That standing army of antibodies then waits. If the pathogen they’re trained to fight arrives, they attack it before an infection takes hold. But the ‘outside’ mechanism is just as important — widespread vaccination reduces the ability of a disease to circulate. With fewer infected people walking around, fewer infected people are passing the disease along.”

Known as “herd immunity,” it doesn’t only protect the individual, it protects the community, too, particularly the most vulnerable — those who who cannot be immunized because they’re too young or too sick, or have a weakened immune system. For measles, herd immunity must be at least 90 to 95 percent in a population, although there are arguments for aiming higher.

It comes down to what epidemiologists call the “basic reproduction number” (R0) — that is, the number of people who would contract the disease from one infected person if everyone is susceptible and no one is protected against the disease. If the R0 is less than 1, the infection dies out. But the higher the R0, the faster the disease will spread in a population. Measles, for example, is highly contagious. Its basic reproduction number is in the region of 12 to 18, meaning that every person with measles could infect a further 12 to 18 people. In comparison, last year’s devastating Ebola outbreak in West Africa had an estimated basic reproduction number between 1.71 and 2.02. The risk of contracting a disease also has to take other factors into account, such as how the disease is transmitted and how long it remains infectious. The measles virus is spread through the air by coughing and sneezing and can survive in the air for up to two hours. An infected person can spread the virus for four days before and after a rash appears. The more contagious a disease, the higher the vaccination rate must be to protect the herd.

One of the biggest public health threats is not the diseases themselves but the vaccine hesitancy that keeps parents from vaccinating their children.

So even though national MMR immunization rates are as high as 94 percent, those pockets where herd immunity falls below 90 percent — in Colorado the state average is 86.9 percent — are risking an outbreak. In Syria, for example, where vaccination rates have fallen to 45 percent from a pre-conflict high of 95 percent, a resurgence of polio paralyzed 35 children in 2013. Measles and whooping cough followed in 2014.

Out of sight is out of mind. Vaccines have been so successful at reducing disease that we are rarely confronted with their devastating effects. Before the US measles vaccine was licensed in 1963, 3 to 4 million people a year contracted the disease, and 400 to 500 of them died . This year, there have been 19 cases in the US. Very few people fear smallpox or polio anymore, says Haelle, and in a sense, fear of the vaccine has replaced the fear of the disease. “The information that’s most accessible to us stays at the front of our minds,” she says — and we have access to more information than we ever had in the past. We tend to hear more about vaccine injury – whether true or not – than about the effects of the diseases we’ve eradicated. That influences how we think about risk, a process called availability bias – our natural tendency to fixate on whatever’s obvious, rather than whatever is relevant.

Opportunities for seeding doubt are plentiful, says Dr. Sharon Kaufman, chair of the Department of Anthropology, History and Social Medicine at the University of California San Francisco. Websites and discussion groups, state’s personal-belief exemptions, class-action lawsuits and books such as What Your Doctor Doesn’t Tell You About Children’s Vaccination all foster doubt and skepticism of experts and scientific evidence, Kaufman says.

But the bare facts are pretty clear. Oceans of research have shown that the risk of a very serious reaction to a vaccine is extremely rare — 1 in 1 million doses, according to the CDC. Seizures after vaccines, while terrifying for parents, are also very rare, a new study has concluded.

Meanwhile, the risk of a child with measles contracting pneumonia is 1 in 20. Around 1 in every 1000 children with measles may develop encephalitis, a swelling of the brain that can cause deafness or intellectual disability, and for around 1 or 2 of every 1000 children, measles is even fatal.

A lingering legacy. It’s not just allergic reactions that parents fear. In 1998, a now-discredited study by Andrew Wakefield and colleagues suggested there was a link between the MMR vaccine and autism, causing panic among parents across the world. The paper was retracted, and Wakefield’s medical license was revoked, but the paper caused lasting damage. In the US, it left a lingering feeling of uncertainty, a sense among parents that they should be afraid of vaccines, even if they’re not sure why, says Dr. Elizabeth Rosenblum, a family medicine physician at UC San Diego.

Among her patients, Rosenblum sees parents who either refuse vaccines or who want to vaccinate on their own schedule. Some parents fear that giving their baby multiple vaccines will overwhelm their immune system, although all the evidence shows there’s no truth to this claim.

Newborn babies are confronted by millions of microbes before they even leave the hospital, Rosenblum tells new parents, far more than the immunological components in three or four vaccines. She likens choosing a delayed vaccination schedule to a decision to drive with your baby on your lap, waiting until the next block to put them in their car seat. “That baby is unprotected during that time,” she says.

Inaction feels safer than action. The tendency to avoid an action with a tiny risk of harm in favor of inaction that carries a greater risk is also at play here, says Haelle. It’s known as “omission bias.” In this case, parents are choosing between the perception of immediate danger – the apparent threat of a needle entering their infant’s arm or leg, or the tiny risk that their child will experience a reaction to the vaccine – and the future chance that their child will contract a disease, which may seem remote and abstract.

Facts and education don’t help. Those firmly held biases and beliefs can be much stronger than our intellectual reasoning, so “giving parents the facts doesn’t necessarily change their minds,” says Haelle. In fact, a recent study by Brendan Nyhan, a political scientist at Dartmouth College focusing on politics and health, showed that countering a parent’s concerns with information and images about the dangers of preventable disease and the safety of the MMR vaccine did not make parents more likely to vaccinate their children.

Some of the twenty states that currently permit unvaccinated children to attend school based on personal-belief exemptions are trying to make those exemptions less convenient, and in some cases using the opportunity to educate parents. Nyhan’s recent study suggests the approach could backfire. Having parents consult with their doctor, who they report is their most trusted source of vaccine information, would be a more promising approach, he says.

Solution: Less vitriol, more empathy. So what’s the solution? “More than anything, confronting vaccine hesitancy requires engagement,” she says. “A person who feels that they’ve been heard will relax, let their guard down. Their cognitive biases are less engaged when the threat of being attacked goes away.” For Haelle, everybody has a role to play, from the individual parent reassuring their peers who are hesitant to vaccinate, to insurance companies increasing coverage for well-child visits so parents can discuss concerns with their doctor. The media can also help by portraying vaccination more accurately -– those images of screaming babies aren’t helpful, and they’re not even accurate (most babies don’t actually scream when getting shots).

We’ll never reach 100 percent of people, says Haelle, but that’s okay. So long as we keep up our herd immunity, with thoughtful communication and empathy, we can at least get close.