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The many faces of vaccine hesitancy

Sunday, April 21, 2019
By Susan Gallagher
Lavanya Vasudevan, Chip Walter, Jeffrey Baker

Parents across the world can agree on at least one thing: they want the best for their children. And for most, “the best” includes good health and well-being. So why do some parents put their children at risk of dangerous, potentially deadly infectious diseases by not getting vaccines according to the schedule prescribed by the Centers for Disease Control and the World Health Organization? 

The answer to that question is extremely complicated, which is part of why vaccine hesitancy—a reluctance or refusal to vaccinate despite availability of vaccines—remains such a vexing problem for the international public health community. In fact, it’s been named one of the top 10 global health threats in 2019.

The reasons behind vaccine skeptics’ hesitancy vary widely, and their reluctance to vaccinate their children also takes different forms. Some parents refuse all vaccines for their children, while others reject only certain ones or just don’t follow the recommended schedule, spacing vaccinations out over longer periods of time. And because of this wide variance, increasing vaccine acceptance requires highly tailored strategies to respond to specific concerns. 

Several Duke researchers, including Duke Global Health Institute faculty member Lavanya Vasudevan and pediatricians Jeffrey Baker and Chip Walter, are among those trying to better understand the complex reasons behind vaccine hesitancy and identify more effective ways of allaying vaccine concerns.

It's not just about your child

Deciding whether or not to subject your child to vaccine shots may feel like an intensely personal decision, but it’s actually a choice that can affect the health of others within the community and beyond.

“To many parents, it just doesn’t seem right that they have to yield to the community. They feel it should be a decision they’re making for just their kids,” says Jeffrey Baker, a professor of pediatrics at Duke.

Vaccine hesitancy has contributed to countless outbreaks throughout history. In recent years, for example, a rise in anti-vaccine sentiment has contributed to a resurgence of measles in the United States: as of April 19, 626 individual cases of measles have been confirmed in 22 states, the second-highest number of cases reported in the U.S. since measles was eliminated in 2000. But diseases like measles don’t only affect children of parents who opt out of vaccinations.

To many parents, it just doesn’t seem right that they have to yield to the community. They feel it should be a decision they’re making for just their kids. --Jeffrey Baker, MD, professor of pediatrics

The more people in a community who are immune to diseases through vaccinations, the less likely that those who haven’t been vaccinated will come into contact with an infectious individual. This “herd immunity” protects those who cannot be vaccinated—for example, children with compromised immune systems or cancer—from vaccine-preventable diseases.

“Some people lose sight of the fact that there’s a whole population of kids that are so sick that they can’t benefit from vaccines,” says Lavanya Vasudevan, an assistant professor of family medicine and community health and global health. “From a social perspective, we need to protect those kids, which is one of the reasons parents should vaccinate their children.”

Context matters

History shows that one strategy that has never worked well is to force vaccinations onto an unwilling public. At the turn of the 20th century in the U.S., for example, libertarian concerns against government interference and a strong belief in individual liberties fueled a movement against the smallpox vaccination, says Baker, a medical historian who studies vaccine history and controversies.

“Enforcers would go door to door and ask people to agree to be vaccinated, show evidence of vaccination or be given a fine,” he says. “It was a fairly intrusive kind of enforcement at a time when government involvement in people’s lives on this level was not commonplace, and it provoked a pretty widespread reaction.”

Similarly, today’s culture of individualism and consumerism in the U.S. also affects parents’ decisions about vaccinations. “A lot of Americans think about medicine from an individual consumer point of view,” Baker says. For decades now, he notes, patients tend to want to make their own health decisions, rather than a doctor or government telling them what to do. This mindset also applies to parents considering vaccinations for their children.

Resistance to compulsory vaccinations is one of the main factors of vaccine hesitancy identified by a World Health Organization working group in a 2015 report. The group offered a model that outlines three categories of factors contributing to vaccine hesitancy: contextual influences, individual and group influences, and vaccine-specific issues. Vasudevan, Baker and Walter have seen these influences at play in their research and, for Baker and Walter, in their clinical practice as well.

Baker points to a mistrust of the pharmaceutical industry—an issue parents raise during vaccine discussions in his pediatric practice—as another contextual influence. Some parents, he says, suggest that pediatricians are motivated to heavily promote vaccines because of their connections or presumed ties to the industry that develops them.

Vasudevan, who has conducted vaccine hesitancy research in Tanzania, Honduras and the United States, cites another contextual influence in rural Tanzania: while a community may have access to recommended vaccinations, a host of unpredictable circumstances can complicate their ability to take advantage of them. Women in one study, for example, expressed frustration about the cost of traveling to the clinic, long wait times at the clinic and unreliable electricity sources to keep vaccines refrigerated, which sometimes means their children aren’t vaccinated despite their diligence in getting to the clinic. These hassles can lead to ambivalence about pursuing future vaccinations for their children.  

News stories and especially the opinions of high-profile celebrities also can heavily influence the context around parents’ decisions. Other contextual factors include religious beliefs and a country’s past experiences with vaccines. 

My friends, my family and me

Personal experiences with vaccines—or those of friends and family members—can also influence our attitudes about vaccines. Take the flu, for example: “Many people believe that the flu vaccine gives you the flu, and they will tell you stories about how that happened to them or to a friend,” Baker says. “But that can’t be true, because it’s an inactivated vaccine.” Rather, contracting the flu after receiving a vaccination for it typically happens because the vaccines are given during winter, a time of year when many viruses and bacteria are circulating. People also tend to conflate the flu with any viral infection. 

Parents’ knowledge about vaccines is another factor in their decision-making. For instance, most people Vasudevan has encountered through her research in the Mtwara region in southeastern Tanzania know that vaccines are important, but they may not understand the details of how they work or why they’re beneficial. In these communities, people rely primarily on healthcare providers for vaccine information, but often the provider doesn’t have the bandwidth to counsel parents and respond to their questions. “At one health facility I visited, a group of 40 or so mothers were waiting to get services for their children from one provider,” she recalls. “There’s just not enough time.” Lack of understanding about vaccines may influence a parent’s commitment to the prescribed vaccine schedule. 

Some parents may refuse or delay a vaccine because they perceive the risk of catching the targeted disease as too remote or too far into the future to take action. Duke pediatrician and researcher Chip Walter sees this mindset play out with the vaccine for human papilloma virus (HPV), a sexually-transmitted virus that can cause cervical cancer. The vaccine is typically administered to pre-teen boys and girls. In this age range, children are at varying stages of maturity, and sometimes it’s difficult for parents to appreciate or acknowledge that their child will eventually be sexually active, he says. 

“Vaccines are prevention for future possible diseases,” he says. “The risk of getting cervical cancer isn’t immediate, whereas acquiring an illness like meningitis is potentially immediate.”

Beliefs about health prevention, trust or distrust in authorities involved in vaccinations and peer group norms are examples of other individual and group influences.

Taking aim at vaccines

One of the biggest drivers of vaccine hesitancy revolves around perceptions of safety. Fears of risks and side effects—many unwarranted—are a prime reason parents refuse vaccines. In the 1970s, for example, the Diphtheria, Tetanus and Pertussis (DTP) vaccine was alleged to cause high fevers, seizures and even permanent brain damage, causing some parents to reject the vaccine for their children. Although large epidemiological studies eventually proved the safety of the vaccine, many people remained skeptical. Similarly, concerns about the Measles, Mumps and Rubella (MMR) vaccine leading to autism surfaced in the 1990s and still linger among some groups despite strong scientific evidence to the contrary.

Other parents may not question the safety of a vaccine or set of vaccines but are wary of multiple vaccines administered simultaneously, either as several shots or as a few vaccines given with one shot. As a result, they opt to delay some vaccines. “Some parents feel that giving so many antigens in the same visit is not healthy for the child,” says Vasudevan. “The perception is that we’re over-burdening the child’s immune system, but we’re actually constantly exposed to pathogens and antigens that stimulate our immune system in our daily lives.”

Baker notes that spacing out vaccines feels like a compromise to many parents who struggle to navigate the complex web of vaccine information they read and hear from various sources. “You’re trying decide what’s right for your child. You go onto the Internet. You read different things. You try to decide whom to trust, but the sides of the argument can get pretty complicated,” he says. “One response is to pick what seems like an in-between, middle-of-the-road approach.”

But this approach is problematic, Baker notes, not just because it puts children at risk of getting vaccine-preventable diseases during the delay, but also because it’s difficult for physicians and parents to keep track of alternate vaccine schedules.

Other vaccine-specific concerns that can lead to vaccine hesitancy include cost, how the vaccine is administered, and the extent to which a person’s health care provider expresses confidence in the vaccine.

Read the entire article on DGHI