From a public health perspective, the story of the twentieth century was, in many
ways, the story of the success of vaccines. Smallpox, once a horrific scourge, was
targeted by a global campaign that culminated in eradicating the disease in 1977.
Today, the endgame of polio eradication is playing out in a small handful of nations
where the disease remains endemic. In the United States, mandatory school vaccination
laws have led to the virtual elimination of many deadly infectious diseases, including
diphtheria, measles, mumps, polio, rubella, and Haemophilus influenza type
Looked at in one light, the country seems well positioned to continue these successes:
The vast majority of parents in the United States immunize their children in accord
with the recommended vaccine schedule. What’s more, national surveys indicate that
a majority of parents whose children are not fully vaccinated support immunization
but are poorly served by the health care system due to factors including lack of
access to primary care, lack of insurance coverage, inadequate medical treatment
and follow-up, and failure to enforce school-entry immunization requirements.7 (Addressing these issues
will require fundamental changes in health care practices in this country and were
therefore outside the scope of the Academy workshop.)
That leaves us with parents who are deliberately deferring or declining vaccines.
Any clear-eyed assessment of the situation needs to acknowledge that their numbers
are going up, not down. The results of this disturbing reality can be seen in costly
outbreaks in communities with high numbers of deliberately unvaccinated children.
In 2011, the nation experienced its largest number of individual measles cases (222
individuals) and outbreaks (17) since 1996; this is especially notable because the
World Health Organization (WHO) declared measles eliminated from the United States
in 2000. The index case in virtually every one of those recent outbreaks was an
individual who was either deliberately unvaccinated—often a U.S. resident
travelling abroad—or of unknown vaccine status.8 We need only look to France to see how quickly
a seemingly contained disease can spiral out of control: In 2007, there were 40
reported cases of measles infections in that country. That figure jumped to 600
in 2008—and rose to more than 15,000 in 2011.9 Six of those cases resulted in death. Translating
that rise to a population the size of the United States’ gives you more than 70,000
measles infections—and an estimated public sector cost of hundreds of millions
The recent measles outbreaks in the United States and Western Europe are especially
tragic because the MMR vaccine is overwhelmingly effective, which means virtually
every single one of those cases could have been prevented. (Measles continues to
claim some 158,000 lives annually, or about 430 lives every day, with most victims
under the age of five. More than 95 percent of deaths occur in low-income countries
with weak public health infrastructures.10)
And it is not just measles that is on the rise: In 2012, 48,277 cases of pertussis
(whooping cough) were reported to the federal Centers for Disease Control and Prevention
largest number in more than half a century, up from a modern low of about 1,000
cases in 1976.12
In developing countries, hard-won advances can vanish in a blink of an eye: After
one state in Nigeria ceased universal polio immunization in 2003 because of spurious
fears that the vaccine was being used to sterilize Muslims, the disease was reintroduced
to twenty previously polio-free countries within three years.13
Research has clearly shown that parental attitudes toward vaccines fall along a
continuum ranging from total acceptance to total refusal. When we define vaccine-hesitant
parents not only as those who selectively vaccinate or delay some vaccines but also
as those who have some misgivings about vaccines, a substantial number—between
20 and 30 percent—end up in this category.14
Today, the term “vaccine hesitancy” has gained acceptance, a shift in terminology
that reflects not only this more nuanced understanding of parents’ positions, but
also the importance of engaging and supporting those whose attitudes are not on
one end of the spectrum or the other. Constructive dialogue between providers and
parents can promote informed decision-making and help public health professionals
better understand the concerns underlying vaccine hesitancy.15
WHY DO PARENTS SAY NO?
Recent history shows the devastating effects of inaccurate information about vaccines.
In 1998, press coverage of British physician Andrew Wakefield’s specious claims
linking the MMR vaccine to bowel disease and autism caused public confidence in
the vaccine to plummet. In England, MMR coverage rates dropped from nearly 93 percent
in 1997 to 79.9 percent in 2003–2004.
And once doubt is planted, it is hard to uproot. In a 2011 survey taken immediately
after the Wakefield study was retracted and Wakefield was accused of fraud, 27.9
percent of respondents said they still believed there was a link between vaccines
and autism. In a stark illustration of the fact that simply restating a discredited
fear can cause people to believe it is true, 5.6 percent of respondents said they
were convinced that there was a link between vaccines and autism only after
the news reports discrediting Wakefield’s study as fraudulent were aired.16
What else drives the vaccine confidence gap? Surveys and studies point to a myriad
of reasons that parents request non-medical exemptions. Some are so unfamiliar with
the diseases vaccines protect against that they conclude the vaccines themselves
are unnecessary. Others cite concerns with vaccine safety broadly or rare vaccine
side effects specifically, while questioning the efficacy of giving vaccines to
healthy people in the first place. Some believe that vaccines overload children’s
immune systems, or that “natural immunity” is preferable to vaccine-induced immunity;
others believe that their children can avoid vaccination because a high enough percentage
of the population is vaccinated to keep a given disease at bay. (Choosing not to
vaccinate for that reason was described by one popular anti-vaccine doctor as “hiding
in the herd.”17)
Some parents cite their belief in alternative medicines; others are distrustful
of the medical system, science, or anything recommended by government in general.18
On a more individual level, social science has shown that individuals have different
styles of decision-making. Some parents accept social norms; others are more apt
to rely on doctors, parents, or friends for advice. There are also those who scour
the primary academic literature in an attempt to understand the science behind vaccines.19
It is also important to remember that decisions about vaccination are not made at
a single point in time. Many parents have indicated that they began mulling the
issue even before deciding to have a child. Pregnancy—a time of active information
seeking—appears to be an especially formative time for thinking about vaccination.
THE SOCIAL GOOD
As experts focus on the reasons why parents are reluctant to immunize their children,
it is important to note the reasons they do opt for vaccination. While
the main reason parents endorse vaccination is to protect their own children, protecting
the community is also a salient rationale. A 2012 review article found that while
only 1–6 percent of parents spontaneously name benefits to others as a primary reason
to vaccinate, some 30–60 percent agreed with that assessment when asked if it is
an important reason to vaccinate.20
In other words, the altruistic motive to vaccinate may be stronger than is widely
assumed—an untapped area of research that could yield new approaches to public
THE CLINICAL CONVERSATION
One of the liveliest workshop discussions focused on the importance of the vaccine
conversations that doctors, nurses, pharmacists, and other providers have with parents—both
because it is a time when parents can receive accurate information and because it
is a chance for providers to gain insight into parents’ vaccine knowledge, attitudes,
Workshop participants discussed the types of research that would help physicians
best prepare for this conversation. Is one type of vaccine-hesitant parent more
likely to respond to an argument about societal obligations while another type responds
most strongly to a discussion of the diseases themselves? Is there any way to identify
vaccine-rejecting parents whose minds will never be changed?
Workshop attendees also discussed a finding that has emerged from recently published
research: Parents who are told by providers what vaccines their children will get
are less likely to resist those recommendations than parents whose providers ask
them for their input on vaccines.21
7 Philip J.
Smith et al., “Parental Delay or Refusal of Vaccine Doses, Childhood Vaccination
Coverage at 24 Months of Age, and the Health Belief Model,” Public Health Reports
126 (supplement 2) (2011): 135–146.
for Disease Control and Prevention, “Measles—United States, 2011,” Morbidity
and Mortality Weekly Report (MMWR) 61 (15) (April 20, 2012): 253–257, http://www.cdc.gov/mmwr/preview/mmwrhtml/mm6115a1.htm?s_cid=mm6115a1_w;
Centers for Disease Control and Prevention, “Measles Press Conference: 50th Anniversary
of Measles Vaccine,” Press Briefing Transcript, December 5, 2013, http://www.cdc.gov/media/releases/2013/t1205-measles-threat.html.
9 WHO Regional
Office of Europe, Immunization Highlights, 2011–2012 (Copenhagen, Denmark:
WHO Regional Office for Europe, December 2, 2011), 9.
Health Organization, “Measles, Fact sheet N°286,” updated February 2014, http://www.who.int/mediacentre/factsheets/fs286/en/.
for Disease Control and Prevention, “Pertussis Outbreak Trends,” updated September
Institutes of Health, “How To Whip Whooping Cough,” News in Health, June
Health Organization, “Poliomyelitis in Nigeria and West/Central Africa,” World Health
Organization Global Alert and Response, June 18, 2008, http://www.who.int/csr/don/2008_06_18/en/.
J. Opel et al., “Development of a Survey to Identify Vaccine-Hesitant Parents,”
Human Vaccines and Immunotherapeutics 7 (4) (April 2011): 419–425, doi:
J. Larson, “Negotiating Vaccine Acceptance in an Era of Reluctance,” Human Vaccines
and Immunotherapeutics 9 (8) (July 29, 2013): 1779–1781.
J. DeNoon, “WebMD Survey: Safety Biggest Vaccine Worry for Parents,” WebMD,
March 31, 2011, http://children.webmd.com/vaccines/news/20110329/webmd-survey-safety-biggest-vaccine-worry-parents?page=2.
Sears, The Vaccine Book (New York: Little, Brown, 2007), 96–97.
18 J. S.
Rota et al., “Processes for obtaining non-medical exemptions to state immunization
laws,” American Journal of Public Health 91 (2001): 645–648; Heidi J. Larson,
“Public Trust in Vaccines: A Global Perspective,” The Vaccine Confidence Project,
London School of Hygiene & Tropical Medicine, presented at Public Trust in Vaccines:
Defining a Research Agenda, September 26, 2013.
K. Brunson, “How Parents Make Decisions about their Children’s Vaccinations,” Vaccine
31 (46) (November 2013): 5466–5470.
Quadri-Sheriff et al., “The Role of Herd Immunity in Parents’ Decision to Vaccinate
Children: A Systematic Review,” Pediatrics 130 (3) (September 1, 2012):
522; originally published online August 27, 2012, doi: 10.1542/peds.2012-0140.
J. Opel et al., “The Architecture of Provider-Parent Vaccine Discussions at Health
Supervision Visits,” Pediatrics 132 (6) (December 2013): 1037–1046; published
November 4, 2013, doi:10.1542/peds.2013-2037.