Content uploaded by Heidi J Larson
Author content
All content in this area was uploaded by Heidi J Larson on Dec 31, 2020
Content may be subject to copyright.
Series
526
www.thelancet.com Vol 378 August 6, 2011
Lancet 2011; 378: 526–35
Published Online
June 9, 2011
DOI:10.1016/S0140-
6736(11)60678-8
See Comment Lancet 2011:
378: 296, 298, and 382
This is the fi fth in a Series of
fi ve papers about the new
decade of vaccines
Department of Infectious
Disease Epidemiology, London
School of Hygiene and Tropical
Medicine, London, UK
(H J Larson PhD); Department
of Paediatrics, College of
Physicians and Surgeons,
Columbia University,
New York, NY, USA
(Prof L Z Cooper MD); National
Institute for Health and
Welfare (THL), Helsinki,
Finland (J Eskola MD);
Department of Paediatrics,
Duke University, Durham, NC,
USA (Prof S L Katz MD);
Government Aff airs and
Policy, Johnson & Johnson,
New Brunswick, NJ, USA;
(S Ratzan MD); and Journal
New Decade of Vaccines 5
Addressing the vaccine confi dence gap
Heidi J Larson, Louis Z Cooper, Juhani Eskola, Samuel L Katz, Scott Ratzan
Vaccines—often lauded as one of the greatest public health interventions—are losing public confi dence. Some vaccine
experts have referred to this decline in confi dence as a crisis. We discuss some of the characteristics of the changing
global environment that are contributing to increased public questioning of vaccines, and outline some of the specifi c
determinants of public trust. Public decision making related to vaccine acceptance is neither driven by scientifi c nor
economic evidence alone, but is also driven by a mix of psychological, sociocultural, and political factors, all of which
need to be understood and taken into account by policy and other decision makers. Public trust in vaccines is highly
variable and building trust depends on understanding perceptions of vaccines and vaccine risks, historical experiences,
religious or political affi liations, and socioeconomic status. Although provision of accurate, scientifi cally based evidence
on the risk–benefi t ratios of vaccines is crucial, it is not enough to redress the gap between current levels of public
confi dence in vaccines and levels of trust needed to ensure adequate and sustained vaccine coverage. We call for more
research not just on individual determinants of public trust, but on what mix of factors are most likely to sustain public
trust. The vaccine community demands rigorous evidence on vaccine effi cacy and safety and technical and operational
feasibility when introducing a new vaccine, but has been negligent in demanding equally rigorous research to
understand the psychological, social, and political factors that aff ect public trust in vaccines.
Introduction
Tremendous progress has been made in the development
of new vaccines, along with increasing access to new and
underused vaccines in the lowest income countries. But,
vaccines—often lauded as one of the greatest public
health interventions—are losing public confi dence. Some
vaccine experts describe the problem as a “crisis of public
confi dence”1 and a “vaccination backlash”.2
Public concerns about vaccine safety and vaccine
legislation are as old as vaccines themselves—dating
back to the anticompulsory vaccination league against
mandated smallpox vaccination in the mid-1800s.3,4 Some
common concerns shared by the antivaccination groups
of the 1800s and those of today are related primarily to
arguments against mandated vaccination, or imposed
vaccine schedules. But current antivaccination groups
have new levels of global reach and infl uence, empowered
by the internet5 and social networking capacities allowing
like minds to rapidly self-organise transnationally,
whether for or against vaccines.6 These groups reach
people who are not necessarily against vaccines, but who
are seeking answers to questions about vaccine safety,
vaccine schedules, changing policies, and the relevance
of some new, and old, vaccines. Vaccines evoke concerns
diff erent from other health interventions because many
healthy people need to be vaccinated to achieve a
protective public health benefi t.
Several factors drive public questions and concerns:
perceptions of business and fi nancial motives of the
vaccine industry and their perceived pressures on
public institutions—such as during the H1N1 infl uenza
response; coincidental rather than causal adverse events
that are perceived as vaccine related; challenges in
manage ment and communication of uncertainty about
risks7 (including serious, albeit rare, ones); less risk
tolerance for vaccines given to those who are healthy
than for drugs given to treat an illness; scepticism of
scientifi c truths, which later become untruths, or
amended truths as new research becomes available;8
elitism of a group of people that believe they should not
risk vaccination of their child if enough other children
are being vaccinated; and, in some cases, outright non-
acceptance of scientifi c evidence such as in the case of
antivaccine movements that persist in the belief that
autism can be caused by thiomersal or the measles,
Key messages
• Public concerns about vaccines are not merely about vaccine safety, but are also about
vaccine policies and recommendations, vaccine costs, and new research fi ndings.
• Public decision making related to vaccine acceptance is complex and is neither
driven by scientifi c nor economic evidence alone, but is also driven by a mix of
scientifi c, psychological, sociocultural, and political reasons, all of which need to be
better understood.
• The internet and new forms of social media have not only allowed for rapid and
ubiquitous sharing of information—and misinformation—but have also allowed new
methods of self-organisation and empowerment of newly founded online
communities that argue against or for vaccines.
• Although communication of positive, evidence-based information about the safety of
specifi c vaccines and their benefi t–risk ratios to the public is crucial, communication
alone will not stop public distrust and dissent against vaccines.
• Levels of public trust in vaccines are highly variable and context specifi c. To sustain or
restore confi dence in vaccines, a thorough understanding is needed of the
population’s—or subpopulation’s—specifi c vaccine concerns, historical experiences,
religious or political affi liation, and socioeconomic status.
• Core principles to be followed by all health providers, experts, health authorities,
policy makers, and politicians include: engagement with and listening to stakeholders,
being transparent about decision making, and being honest and open about
uncertainty and risks.
Series
www.thelancet.com Vol 378 August 6, 2011
527
mumps, and rubella (MMR) vaccine, despite an
abundance of scientifi c evidence that shows no
causal eff ect.9,10
Although communication of candid, evidence-based
information to the public about the safety of specifi c
vaccines and their benefi t–risk ratios is crucial, this
information alone will not stop public distrust and
dissent against vaccines. Public decision making related
to vaccine acceptance is not driven by scientifi c or
economic evidence alone, but is also driven by a mix of
scientifi c, economic, psychological, sociocultural, and
political factors, all of which need to be understood and
taken into account by policy and other decision makers.
We discuss factors in the changing global environment
that have precipitated what some in the specialty of
climate change call “an erosion of trust”,11 caused by a
small minority of climate change sceptics. The vaccine
community faces similar challenges. We examine key
determinants of trust, with specifi c examples in which
public distrust undermined vaccine acceptance and
interrupted immunisation programmes, and, then, what
was done to restore trust. Finally, we outline ways to
improve public trust including future research and
actions that can be taken now.
The changing global environment
Background
Many proposed explanations exist as to why vaccines are
questioned by the public, what exactly is being questioned,
and what can be done to restore public confi dence. One
common perception is that waning public trust in
vaccines is because vaccines have become a victim of their
own success—whereby they have been so eff ective for
prevention of disease that more attention has now been
focused on the potential risks of vaccines than on the
risks of the now less prevalent diseases they prevent. In
high-income countries, lack of familiarity with vaccine-
preventable diseases is present in the health-care
community (eg, nurses, physicians, and others that
administer vaccines),6 many of whom are too young to
have seen these illnesses.
Increased public questioning of vaccines in low-
income countries, where vaccine preventable diseases
are still prevalent, point to other underlying reasons for
public distrust or dissent besides the absence of vaccine-
preventable disease (panel 1). These reasons can be
cultural, religious, or sometimes economic or political,
as in the case of the polio vaccination boycott in
northern Nigeria, where marginalised communities
asserted their voice by refusing or challenging
government-driven initiatives.15
Vaccine safety
Another perception is that vaccine safety is the primary
concern of the vaccine-questioning public. Although
vaccine safety is clearly important, and certainly the
most monitored and addressed concern by national
immunisation programmes and international organ-
isations such as WHO and UNICEF, safety is not the
only concern a growing number of individuals,
communities, and even governments have about
vaccines. Other concerns include aff ordability and
relevance of new vaccines in diff erent settings.
Furthermore, the issue of vaccine safety is now being
viewed in the framework of individual genetic
predispositions to harm, raising fears that adverse events
after immunisation are expressions of uncommon
genetic susceptibilities.16
Diversity of vaccines
In the past decade, the global vaccine industry has
mushroomed in terms of the number of companies
involved and products in development. From 1995
to 2008, the number of vaccine companies that sought
to create or manufacture vaccines doubled to 136, as
did the number of prophylactic vaccine products in
Panel 1: Framework for analysing the development of
public concerns about vaccines
Prompters of public concern
Adverse events after immunisation—generally, such events
that occur locally are stronger prompters of rumours, but an
event reported in a distant location is also a possible prompt;
publication of new research;12 new recommendations or policy
change (eg, removal of thiomersal from vaccines in the USA,
stopping hepatitis B vaccination in schools in France); new
products (ie, introduction of new product or change of current
product source or product packaging); political motivations
(ie, purposefully spreading rumours to undermine the
government, other providers, or producers of the vaccine)
Factors that sustain public concern
Global spread of vaccine-related rumours; frequency of
rumours (eg, occasional rumours vs persisting and
strengthening rumours); media reports that amplify any
prompter of public concern; historical bad experience that
lowers public trust (eg, Pfi zer’s Trovan trial was perceived to
cause childhood deaths in Nigeria, inadequate public
information about the bovine spongiform encephalopathy
outbreak in UK, dishonesty about HIV-infected blood supply
in France);13 socioeconomic marginalisation (ie, populations
that have historically been marginalised with lower access to
health services are less trusting of authorities); previous
existence of self-organised community groups that can
repurpose their experience to address vaccine concerns
(eg, women’s groups organised to question and stop human
papillomavirus vaccine project in India14)
Outcome and eff ects
Vaccine refusals (individual or group level); vaccine
withdrawal (this can be a prompter of rumours and a
consequence of rumours); vaccine-preventable disease
outbreaks (eg, measles, pertussis, poliomyelitis)
of Health Communication,
Washington, DC, USA
(S Ratzan)
Correspondence to:
Dr Heidi J Larson, London School
of Hygiene and Tropical
Medicine, Keppel Street,
London WC1E 7HT, UK
heidi.larson@lshtm.ac.uk
Series
528
www.thelancet.com Vol 378 August 6, 2011
development to 354.17 The list of WHO prequalifi ed
vaccines now has 202 products from diff erent manu-
facturers targeted against 20 infectious agents,18 and the
US Food and Drug Administration (FDA) list of vaccines
available for immunisation in the USA consists of
72 products.19 Most of these products are variations and
combinations of vaccines that have existed for years, and
thus are not really new, but the range certainly seems
complex and confusing to both recipients and providers
of vaccines.
Although the growing numbers of vaccines available or
in development is impressive, the diversity of vaccines—
including vaccines tailored to specifi c populations—has
also contributed to public questioning of vaccine choices
and the relevance of so many vaccines. Other concerns
have arisen about the ability of low-income countries to
aff ord the introduction of new vaccines, especially when
access to even the least expensive vaccines is inadequate.20
Vaccine schedules
As new vaccines are introduced, vaccine schedules
change. Schedules also vary across countries. These
changes and diff erences in vaccine schedules further
contribute to public questioning,1,21 In the WHO listing of
immunisation schedules by antigen and country,22 for
example, selection of a list of schedules for “tetanus and
diphtheria toxoid childrens’ dose” worldwide showed a
listing of 72 countries with 29 diff erent variations of
diphtheria and tetanus schedules. Explanations for these
programme diff erences include variations in the
epidemiological aspects of the diseases and in the
health-care fi nancing and delivery systems between the
countries. However, a substantial part of the variation
cannot be justifi ed on the basis of best public health
practice, and some public questioning is understandable.
New research
Public concerns can also emerge after publication of new
research, such as the 1994 publication by Talwar and
colleagues12 about an antipregnancy vaccine, in which the
mention of tetanus toxoid used as a carrier protein was
misinterpreted. A pro-life Catholic group, Human Life
International, consequently suggested that tetanus
vaccines could cause sterilisation, resulting in vaccine
scares in Mexico, the Philippines, Tanzania, and
Nicaragua. Concerns were also raised by the 1998
publication by Andrew Wakefi eld that proposed links
between the MMR vaccine, autism, and bowel disease.
Although the research was later retracted, Wakefi eld’s
misuse of that work—including statements in the press
conference that were not included in the published
report23—catalysed widespread fears, some of which
persist today.
Government policies
Policy choices or recommendations are also a key public
concern. Such choices that have prompted public debate
and aff ected public trust include: legislation requiring
vaccination for school entry; the US Centers for Disease
Control and Prevention (CDC) and American Academy
of Pediatrics (AAP) recommendation in July, 1999, that
thiomersal be removed from childhood vaccines; and the
decision in France in 1998 to withdraw the hepatitis-B-
vaccination programme from schools.24
Public trust is challenged particularly when public
authorities disagree, such as was the case in 1998 when
the French Government suspended the use of the
hepatitis B vaccine, which went against the recom-
mendation of WHO and the viral hepatitis prevention
board (an expert committee convened by WHO).25 The
result of this decision was that 10 years after the temporary
vaccine suspension, three-dose vaccine coverage with
hepatitis B vaccine was still only 30%.26
Another example of such disagreement was the Japanese
Government’s decision to suspend the pneumococcal
conjugate vaccine Prevnar (Pfi zer, New York, NY, USA)
and the Haemophilus infl uenzae type b vaccine ActHIB
(Sanofi -Aventis, Bridgewater, NJ, USA), while investigating
suspected links of these vaccines with the death of four
children, which prompted widespread media coverage. A
Google search for “Japan” and “Prevnar” and “2011” on
April 7, 2011, 1 month after the vaccines were suspended,
showed more than 85 000 reports globally. Of the fi rst
100 results listed, only three were about the decision to
resume use of the vaccines on March 30, 2011; these three
reports were 45th, 91st, and 93rd in the list. When the
same search was done on WHO and CDC websites, no
information was avail able on either the suspension or
resumption of the two vaccines.
New media and horizontal communication
Democratisation movements and the advent of the
internet have changed the environment around vac cines
from top-down, expert-to-consumer (vertical) com-
munication towards non-hierarchical, dialogue-based
(horizontal) communication, through which the public
increasingly questions recommendations of experts and
public institutions on the basis of their own, often web-
based, research. Such public questioning is not unique
to vaccines, but part of a broader environment of
increasing public questioning and the emergence of
dissent groups, particularly in areas that include risks
such as climate change.
The internet, social media—which allows interactive
exchange between many users—and mobile phone
networks have shifted the methods and speed of com-
munication substantially, allowing information about
vaccines and immunisation to be gathered, analysed,
and used—especially through blogs—very diff erently
com pared with even a decade ago. The amount of
information available has increased greatly, including
scientifi cally valid data and evidence-based recom-
mendations alongside poor quality data, personal
opinions, and misinformation.
Series
www.thelancet.com Vol 378 August 6, 2011
529
Media attempts to balance coverage by provision of
equal opportunity to all viewpoints exacerbates the
challenges to public confi dence in vaccines by allowing
outlier views and small extremist opinions the same
media space as views validated through a rigorous
process of peer review by the scientifi c community. This
disproportionate share of outlier views has been further
amplifi ed by celebrities—such as Jim Carrey or
Jenny McCarthy—who encourage parents to question
vaccines, often telling highly emotional stories of children
who were perceived to have been harmed by vaccines.27
The emergence of social media tools, such as Facebook
with more than 500 million users globally,28 has helped
create new methods of self-organisation and empower-
ment of newly founded virtual communities both locally
and across wide geographical areas, building constitu-
encies that argue against or for vaccines.29–31 Although
some of these networks have a national focus, they are
also quick to pick up and amplify events occurring in
other countries that support their cause.
The new mix of highly varied and often confl icting
information contributes to the scepticism of some
vaccine consumers. These views need to be far better
understood as they are developing, rather than when
vaccination rates start to decline because of distrust.
Determinants of public trust in vaccines
Public trust in vaccines is a complex issue that often
has many converging determinants. Research into
environmental-risk communication has identifi ed three
factors that aff ect the extent to which an individual or
institution is trusted: perceptions of knowledge and
expertise, openness and honesty, and concern and care.32
The credibility of vaccine information, for example, is
infl uenced by the perceived trustworthiness of the
messenger—whether a government authority, the
vaccine industry, a health provider, a friend or colleague,
or the media. To address persisting concerns about oral
polio vaccines causing sterilisation, especially in poorer,
marginalised Muslim populations in northern Nigeria
and Uttar Pradesh, India, WHO and the Global Polio
Eradication Initiative partners convened meetings with
the Organisation of Islamic States, as trusted inter-
mediaries or brokers with the public, to successfully
rebuild trust in the polio vaccine in their Muslim
constituencies. Similarly, when fears spread through
Catholic pro-life groups that the tetanus vaccine had
sterilising elements, WHO offi cials requested that the
Vatican choose the laboratory in which the vaccine was
tested, because it was a trusted institution for these
groups (Ciro de Quadros; Albert B. Sabin Vaccine
Institute, Washington, DC; personal communication).
Whether the public perceives new information about
vaccines as honest and not hiding information about
risks also aff ects public trust in vaccines. Similarly,
openness and transparency in decision making about
new vaccine policies or research processes can infl uence
the trust of the public or interest groups in the
population. The suspension of the human papillo-
mavirus vaccine demonstration project in India, in
April, 2010, is an example of the potential eff ect of
distrust, because of inadequate open dialogue with
groups who question the vaccine.14
Individual and group experiences also aff ect public
willingness to trust vaccines.13 Public trust of the inter-
nationally driven polio vaccination campaign in northern
Nigeria, for example, was undermined by Pfi zer’s trial of
the Trovan vaccine in northern Nigeria, because child
deaths were suspected to be linked to the trials.
The personal nature of a particular vaccine concern is
another determinant of trust, and can mean that
individuals or groups are overly trusting because of an
eagerness for an answer to their concern. In their search
for answers to questions such as “why does my child
have autism?”, individuals and groups might be willing
to trust information that is not scientifi cally proven if it
addresses their concerns.
To improve understanding and address determinants
of public trust in vaccines, and the potential eff ect of
these determinants, research is needed not only into
individual determinants of trust, but on understanding
what mix of factors is most likely to sustain, or damage,
public trust. Risk events, such as an adverse events after
immunisation, or even perceptions of risk, such as fears
of vaccines causing sterilisation or autism, can be
amplifi ed or attenuated, depending on how the event or
perception of the event is communicated to, and
interpreted by, individuals, institutions, or the media.33
Case studies
The following case studies describe examples of how
vaccine risk concerns were prompted and sustained by
individuals—from religious leaders to scientists and
health experts, governmental and non-governmental
institutions, religious and other interest groups, and the
media. The tipping point, whereby vaccines were refused
or programmes were disrupted because of fears, was due
to a convergence of events, creating a “social amplifi cation
of risk”.33
Thiomersal and autism
Thiomersal, a compound containing ethylmercury, has
been used to prevent bacterial contamination in
biologics since the 1930s. In 1997, the FDA noted that,
in view of the increasing number of vaccines given in
early infancy, the total amount of ethylmercury (as
thiomersal) might exceed the level set for methylmercury
by US Environmental Protection Agency guidelines. In
a period of increasing concern about poisoning from
mercury in the environment, the AAP and CDC issued
a joint statement in 1999 asking vaccine makers to
remove thiomersal from childhood vaccines as soon as
practical.34 This statement, issued to show caution and
assure the safety of vaccines, paradoxically supported
Series
530
www.thelancet.com Vol 378 August 6, 2011
the argument of those suggesting that vaccines were
contributing to what was called an epidemic of autism.
Public concern was fuelled by organised groups of
parents convinced that their children’s autism was
caused by mercury-containing vaccines, who prepared
to seek compensation through the US National Vaccine
Injury Compensation Program; a series of hearings by
the chair of an oversight committee in the US House of
Representatives who believed his own grandchildren
had been harmed by vaccines; and studies and
testimonials in public forums, by scientists and
celebrities who are now discredited.
Since 1999, many studies have failed to support any
causal relationship between thiomersal and autism.35,36
The absence of this compound from childhood vaccines
in the USA for almost a decade has not altered the
frequency of autism. After exhaustive review, no evidence
has been identifi ed by the vaccine court, a component of
the US Vaccine Injury Compensation Program, or the
US Institute of Medicine to justify compensation of
claimants on the basis of thiomersal in vaccines.10
This case is an example of the perverse consequences
of application of the precautionary principle, which is
applied when there is scientifi c uncertainty and when
an intervention is deemed necessary before harm
occurs.37 The AAP and CDC joint statement showed the
transparency of vaccine policy, but it did not necessarily
earn trust from those convinced that vaccines are
harmful, and in fact prompted more questioning of the
safety of vaccines. Removal of thiomersal from
childhood vaccines in the USA also created tension
between the USA and global vaccine programmes,
especially in developing countries where direct vaccine
and logistical costs would be prohibitive if thiomersal
were removed and single-dose vaccines were instead
mandated. Additionally, removal of this compound
caused an unexpected temporary decline in rates of
hepatitis B vaccination in infants in the USA (fi gure 1).
However, the precautionary measure was based on
scientifi c evidence available at a given point in time and
a value system based on the best interests of the public.
Had a causal link between thiomersal and autism been
discovered, the recommended early removal of
thiomersal would have been lauded by the public.
Haemophilus infl uenzae type b vaccine in India
Similar tensions between experts occurred in India in
relation to introduction of the H infl uenzae type b
pentavalent vaccine combined with diphtheria, poliovirus,
and tetanus, and hepatitis B virus. Introduction of this
vaccine was challenged by Puliyel and colleagues,39,40 who
asserted that the disease burden in India did not justify
addition of the expensive vaccine.
Puliyel and colleagues also claimed that the disease
burden data were misrepresented by the GAVI Alliance
and WHO.41,42 Indian pediatricians contested their
assertions with evidence on the disease burden of
H infl uenzae type b in India, which they felt made a
compelling case for introduction of the vaccine against
this disease.43 Others accused Puliyel of leading an
antivaccination lobby.44
Puliyel and academic and government colleagues who
share his view reject the antivaccination label. In a
statement published in 2010, they wrote that “we are a
group of pediatricians, healthcare activists, teachers in
public health, and bureaucrats who have championed
Figure 1: Number of children who received the fi rst dose of hepatitis B vaccine less than 5 days after birth (USA, 1999–2000)
Data from the US Centres of Disease Control and Prevention’s morbidity and mortality weekly report.38
0 7 12 17 22 27 32 37 42 47 52 5 10 15 20 25 30 35 40 45 50
0
100
200
300
400
500
600
1999 2000
Week Week
Year
Number of children receiving the first dose of hepatitis B vaccine
Joint statement issued regarding
thiomersal as a vaccine preservative
Number of children
Series
www.thelancet.com Vol 378 August 6, 2011
531
universal immunisation in India throughout our
working lives”. They went on to note that they were
“taken aback” by the fact that their questioning of the
appropriateness of introducing the H infl uenzae type b
vaccine in India was misconstrued as a broad anti-
vaccination movement.31
Although introduction of the vaccine was endorsed by
WHO and the Indian National Immunization Technical
Advisory Group (INITAG), opposition from Puliyel and
colleagues led the Indian Health Ministry to stall
introduction of the vaccine. The Health Ministry
convened an independent expert group to re-examine
WHO and INITAG’s recom mendations. This group has
since concluded that the government should move
forward and accept the GAVI Alliance’s fi nancial support
to the Government of India to allow it to proceed with the
introduction of the vaccine. Nonetheless, the Indian
press picked up the debate and widely publicised Puliyel’s
concerns, which will probably not be forgotten.
MMR vaccine and autism
The public’s eagerness for answers to their felt needs is
another determinant of trust. Wakefi eld’s claims in 1998
that the MMR vaccine could cause autism was embraced
by parents who were eager to fi nd a reason for their
child’s autism. His suggestion that a single-antigen
measles vaccine should be considered as a safer
alternative to the MMR vaccine also gave the parents a
solution. When the then Prime Minister Tony Blair
refused to reveal whether his young son had been given
the MMR vaccine, Wakefi eld’s fi ndings seemed validated.
Although many subsequent studies failed to reproduce
Wakefi eld’s fi ndings,9 and his research paper was formally
retracted,45 the distrust generated around the MMR
vaccine contributed to declines in MMR vaccine coverage
and consequent measles outbreaks.46 Research done in
the UK by the Department of Health showed that overall
trust in the MMR vaccine has recovered at least in Britain,
where the controversy began.47 Wakefi eld continues
public speaking engagements internationally to per-
petuate his views by appealing to vaccine-sceptical
parents—even after being scientifi cally discredited. The
groups that still champion Wakefi eld’s views, especially
in the USA, are a stark example of the vulnerability of
public confi dence in vaccines.27,48,49
Tetanus vaccine and sterilisation
In the case of fears related to sterilisation caused by
tetanus vaccines in the early 1990s, a Catholic organisation
with membership in more than 60 countries, popular
media, religious and political leaders, and legislative
authorities converged to amplify perceived risks of
sterilisation associated with vaccination, which led to
reduced uptake of the tetanus vaccine and vaccine
programme disruptions.
In 1994, a research article on a birth control vaccine12
made reference to the use of tetanus toxoid as a carrier
protein. Although the birth control vaccine had no
relation with tetanus immunisation, it created a perceived
connection between tetanus vaccination and contraception
that travelled widely thoughout the internet; Human Life
International communicated this perceived connection
to their members in more than 60 countries. In the
Philippines, the tetanus vaccination campaign was
interrupted by a court injunction. The subsequent panic
led to a 45% drop in tetanus vaccination coverage
between 1994 and 1995.50 In Nicaragua, Catholic Cardinal
Obando, a member of Pro-vida, played a substantial part
in stopping the tetanus immunisation campaign in that
region.47 In Mexico, the Comite Pro-vida accused the
government of genocide, claiming that the tetanus
vaccine caused abortion. Although the damage caused by
these antivaccination campaigns has been largely
mitigated by proactive measures by the Pan American
Health Organization—through engagement with the
media and the Vatican—the notion that vaccines contain
sterilising substances periodically resurfaces, most
recently in the polio campaigns in Nigeria and India.51
Oral polio vaccine and sterilisation
In northern Nigeria, religious and political leaders, led
by the chairman of the Supreme Council for Sharia in
Nigeria, Datti Ahmed, boycotted the polio vaccine
in 2003, claiming that the oral polio vaccine was
contaminated with HIV and could also cause sterilisation
in those vaccinated, fuelling widespread public distrust.
Political and cultural disparities between northern and
southern Nigeria also infl uenced the willingness of the
people in the north to sign-up to a mandate thought to
be imposed by the head of state, and international health
bodies.15 Memories of the Trovan trial in 1996, during
which children died, were still vivid in the minds of
many, undermining their trust. Although subsequent
investigation did not attribute the children’s deaths to
the drug being tested, the trial was deemed illegal
because of unethical conduct.52 The legal proceedings of
the trial, which were undertaken in the northern state of
Kano, took place in the background of the polio
vaccination boycott.
The boycott of oral polio vaccination in Kano State
lasted 11 months and poliomyelitis cases in Nigeria rose
from a nadir of 56 in 2001 to 1143 in 2006. Spread of the
poliovirus in Nigeria led to outbreaks in 15 other sub-
Saharan nations,53 and spread as far as Indonesia where
303 cases were all traced to Nigeria.54
This boycott was a wake-up call to the Global Polio
Eradication Initiative on the need for better engagement
with both local leaders and aff ected communities. At the
60th World Health Assembly, a report on poliomyelitis55
called on member states to improve engagement with
local and national leaders and with aff ected communities.
Although calls for public engagement are not new, the
polio experience has prompted detailed, research-driven
communication and public engagement strategies.
Series
532
www.thelancet.com Vol 378 August 6, 2011
The Global Polio Eradication Initiative has done
extensive, block-by-block research in some settings to
understand who are locally trusted sources of vaccine
information and who are the trusted providers of
vaccines, and to understand the reasons behind vaccine
refusals.56 In Pakistan, research showed that some of
the public resistance was actually among health
workers, who felt underpaid and perceived the initiative
as being imposed from outside Pakistan, and was not
locally owned.57 Understanding how to build and restore
trust can only be addressed with research.58 In the case
of the Global Polio Eradication Initiative, the need for
improved understanding of specifi c public concerns
and reasons for distrust came only in the face of a crisis
of confi dence. The lesson learned was that not only is
research within the local communities needed, but that
it is needed early on in the planning of vaccination
programmes, well before a crisis occurs.
Eff ects of public distrust
Evidence about the eff ects of misinformation, rumours,
and antivaccine groups on vaccine coverage and
consequent disease outbreaks in many countries is well
documented. In addition to the polio, tetanus, and MMR
vaccine examples, increases in pertussis outbreaks have
occurred in Russia,59 Japan, the USA, Sweden, and
England and Wales after antivaccine activity.60 In France,
the political decision to suspend hepatitis B vaccines in
schools exacerbated public concerns associating
hepatitis B vaccines with autism, multiple sclerosis, and
leukaemia and led to low levels of hepatitis B vaccination.61
In the Ukraine, scares and negative public reaction to a
measles and rubella vaccination campaign led to
quarantining of the vaccine and suspension of the
campaign, which was targeting 7·5 million people, but
only reached 116 000.62
In all of these situations, management of the eff ects
of declines in vaccine uptake, consequent disease
outbreaks, and loss of public trust in the vaccines has
taken a toll on human and fi nancial resources in
addition to long-term reputational costs to individual
vaccines and immunisation programmes.
New methods of communication, dialogue, and
engagement are urgently needed across all vaccine stake-
holders—vaccine experts, scientists, industry, national
and international health organisations, policy makers,
politicians, health professionals, the media, and the public.
No single player can reverse the vaccine confi dence gap.
The way forward: who needs to do what?
The foregoing examples show that the process of
building, rebuilding, and sustaining public trust in
vaccines is highly variable and depends on a thorough
understanding of the community and its socioeconomic
status, previous experience, views of those they trust (and
distrust) including religious or political leaders, and
understanding of the risks and benefi ts of vaccines versus
the diseases they prevent.
Traditional principles and practices of vaccine com-
munication remain valid,63 especially those that ensure
timely and accurate communication of information
about where, when, and why vaccines are given, and
those that ensure mutual respect in health provider–
patient interaction. However, additional emphasis
should be placed on listening to the concerns and
understanding the perceptions of the public to inform
risk communication, and to incorporate public pers-
pectives in planning vaccine policies and programmes.
Figure 2: Research into who parents trust
Data were provided by David Salisbury (Department of Immunisation, Department of Health, UK). (A) Who parents trust to give advice about immunisation (2010);
data are for parents of children aged 0–4 years (n=1730). (B) Who parents trust to give advice about immunisation (2007–10); data are for parents of children aged
0–2 years (n=1142). GP=general practitioner. HV=health visitor. PN=practice nurse. NHS=national health service. *GP data gathered before 2007.
44%
37%
49%
43%
51%
55% 55%
5% 3% 4%
34% 32%
39% 42%
43%
24% 20% 19%
18%
19%
17%
16%
15%
12%
10%
14%
18%
19%
42%
54%
4%
92%
86%
66%
58%
49%
21%
GP*, HV, or PN
NHS
Pharmacist
Government
Media
0
10
20
30
40
50
60
70
80
90
100
0
10
20
30
40
50
60
70
80
90
100
Proportion of patients who strongly agree (%)
November,
2003
November,
2004
November,
2005
November,
2006
November,
2007
November,
2008
February,
2010
Strongly agree
Slightly agree
AB
Proportion of patients (%)
GP, HV, or PN
NHS
Pharmacist
Government
Family or friends
Media
Series
www.thelancet.com Vol 378 August 6, 2011
533
To build public confi dence, it is key to understand
what drives public trust in each community,64–66 and
what are the local perceptions of vaccines and their
risks.1,67–72 According to a US National Research Council
report, risk communication “emphasizes the process of
exchanging information and opinion with the public”.73
Building public trust is not about telling them what they
need to understand better, and it is not merely about
being clearer or teaching parents about risk–benefi t
decision making. Trust is built through dialogue and
exchange of information and opinion. Valuable models
can be drawn from environmental-risk research, which
emphasise the importance of listening to public
concerns and can protect against simplistic solutions to
complex problems.74
Research is needed to understand who the public
trusts. The UK Department of Health, for example,
continues to monitor not only public perceptions of
diff erent vaccines, but also who the public trusts
(fi gure 2). Similar studies are in progress in academic
institutions75 and in the CDC.1 Such eff orts should be
encouraged and funded.
The immunisation enterprise is a complex matrix
involving academia, government, industry, private
clinicians and other health providers, and public-health
systems. Every one of these entities is vulnerable to
public mistrust. Improved communication, dialogue,
and trust-building across these entities is essential. The
private sector is very conscious of consumer confi dence
levels as a metric of success and acceptance of their
products. The public health community needs similar
attentiveness to ensure consumer confi dence if we are
to achieve the potential benefi ts of new and existing
vaccines (panel 2).
Conclusion
Vaccination is a complex social act that eff ects both direct,
perceived self-interest, the interest of one’s children, and
the broader community. The decision leading to
immunisation remains a personal summation of each
individual’s perception of the complexity of information
they receive and their trust in the institutions that
produce, legislate, and deliver vaccines. For vaccines to
realise their full potential in protection of health, public
and private health practices need to take into account the
range of social and political factors that aff ect the public’s
willingness to accept vaccines.
The immunisation community, including scientists,
policy makers, and health providers, needs to come to
terms with the reality that individuals and groups will
continue to question and refuse vaccines. Extremist
antivaccination groups whose minds will not change will
exist. Many people—the majority—who accept vaccines
could change their mind. The focus should be on building
and sustaining trust with those who accept and support
vaccines, while working to understand and address the
growing confi dence gap.
Contributors
HJL, LZC, SLK, and JE outlined the report. HJL prepared the fi rst and
subsequent drafts with input from LZC, SLK, JE, SR. All authors read
and approved the fi nal draft.
Confl icts of interest
JE received funding from Novartis for a pneumococcal advisory meeting
and as a data and safety monitoring board member for meningococcal
and typhoid vaccines. SR edits the Journal of Health Communication, with
faculty appointments at Tufts School of Medicine and George Washington
School of Public Health and Health Services. SR contributed
independently of his principal employer, Johnson & Johnson. Some
technical work, travel (LZC and SLK), and meetings relevant to this work
were funded by the Bill & Melinda Gates Foundation. The funding
organisation had no role in the drafting or direction of this report.
HJL declares that she has no confl icts of interest.
Panel 2: Actions needed
• In view of the heterogeneity of populations, and the local
specifi city of vaccine concerns and trust relations,
strategies to build public trust need to be locally tailored
and not prescriptive in recommendations of what
specifi cally needs to be done by various stakeholders to
build confi dence in vaccines.
• Evidence-based approaches used in risk communication76
should be adopted as core principles by all health providers,
experts, health authorities, policy makers, and politicians
when communicating information about vaccines. These
approaches include engagement with and listening to
stakeholders, and being transparent about decision
making, and honest and open about uncertainty and risks.
• A systematic approach is needed to listen to public
concerns. As with infectious diseases, where surveillance is
essential for disease control, systematic monitoring of
dynamic and evolving vaccine rumours, concerns, and
refusals is crucial to guide prompt responses to build and
sustain public confi dence. Such a surveillance system is
being trialled at the London School of Hygiene and
Tropical Medicine.77
• Decision and policy makers cannot assume what the
public wants without undertaking social science and
decision science research. The vaccine community
demands rigorous evidence for vaccine effi cacy and
safety and the technical and operational feasibility of
initiating a new vaccine initiative or introducing a new
vaccine, but have been negligent in demanding evidence
on the social and political feasibility of introducing new
vaccines and the factors that determine the local
acceptability of vaccines.
• Models of multidisciplinary research for vaccine
introduction are emerging78,79 and need to be expanded.
These models include not only technical and operational
assessments, but also research into social and political
factors that need to be considered in planning the
introduction of vaccines. The Global Polio Eradication
Initiative has shown that monitoring of public concerns
needs to be continuous and responsive, and hand in hand
with the monitoring of technical strategies.54
Series
534
www.thelancet.com Vol 378 August 6, 2011
Acknowledgments
HJL is funded by the Bill & Melinda Gates Foundation as principal
investigator for research on public confi dence in immunisation. The
fi ndings and conclusions in this report are those of the authors and do
not necessarily represent the offi cial position of their employers. We
thank David Salisbury for providing data for fi gure 2 and for useful
discussion on the paper; Anne Louise-Kinmonth for reviewing
subsquent drafts; and Pauline Brocard, Lee Barker, Caitlin Jarret,
Isaac Ghinai, Jay Dowle, Larry Madoff , Melissa Cumming, and
Louise Paushter for researching case studies.
References
1 Black S, Rappuoli R. A crisis of public confi dence in vaccines.
Science 2010; 61: 61mr1.
2 Shetty P. Experts concerned about vaccination backlash.
Lancet 2010; 375: 970–71.
3 Spier RE. Perception of risk of vaccine adverse events: a historical
perspective. Vaccine 2001; 20: S78–84.
4 Poland GA, Jacobson RM. The age-old struggle against
the antivaccinationists. NEJM 2011; 364: 97–99.
5 Bean SJ. Emerging and continuing trends in vaccine opposition
website content. Vaccine 2011; 29: 1874–80.
6 Cooper LZ, Larson HJ, Katz SL. Protecting public trust
in immunization. Pediatrics 2008; 122: 149–53.
7 Campbell P. Understanding the receivers and the reception of
science’s uncertain messages. Phil Trans Roy Soc A (in press).
8 Clements CJ, Ratzan S. Misled and confused? Telling the public
about MMR vaccine safety. J Med Ethics 2003; 29: 22–26.
9 Institute of Medicine. Immunization safety review: vaccines
and autism. Washington, DC: National Academies Press, 2004.
10 Honda H, Shimizu Y, Rutter M. No eff ect of MMR withdrawal on
the incidence of autism. J Child Psychol Psychiatry 2005; 46: 572–79.
11 Tollefson J. An erosion of trust. Nature 2010; 466: 24–26.
12 Talwar GP, Singh O, Pal R, et al. A vaccine that prevents
pregnancy in women. Proc Natl Acad Sci USA 1994; 91: 8532–36.
13 Larson HJ, Heymann DL. Public health response to infl uenza A
(H1N1) as an opportunity to build public trust. JAMA 2010;
303: 271–72.
14 Larson H, Brocard P, Garnett G. The India HPV-vaccine
suspension. Lancet 2010; 376: 572–73.
15 Yahya M. Polio vaccines—diffi
cult to swallow. The story of a
controversy in northern nigeria. Working paper 261. Institute of
Development Studies 2006. http://www.eldis.org/vfi le/upload/1/
document/0708/DOC21227.pdf (accessed Jan 6, 2011).
16 Poland GA. Vaccidents and adversomics. Vaccine 2010; 28: 6549–50.
17 Davis MM, Butchart AT, Coleman MS, et al. The expanding vaccine
development pipeline, 1995–2008. Vaccine 2010; 28: 1353–56.
18 WHO. WHO prequalifi ed vaccines. http://www.who.int/
immunization_standards/vaccine_quality/PQ_vaccine_list_en/
en/index.html (accessed Oct 15, 2010).
19 US Food and Drug Administration. Complete list of vaccines
licensed for immunisation and distribution in the US. http://www.
fda.gov/BiologicsBloodVaccines/Vaccines/ApprovedProducts/
UCM093833 (accessed Oct 15, 2011).
20 WHO, UNICEF, World Bank. State of the world’s vaccines and
immunization, 3rd edn. Geneva: World Health Organization, 2009.
21 Lopalco PL, de Carvalho HG, Kreidl P, Leitmeyer K, Giesecke J.
Childhood vaccination schedules in Europe vary widely: is this a
problem? Bundesgesundheitsblatt Gesundheitsforschung
Gesundheitsschutz 2009; 52: 1095–98.
22 WHO. WHO vaccine preventable diseases monitoring system.
http://apps.who.int/immunization_monitoring/en/
globalsummary/scheduleselect.cfm (accessed March 30, 2011).
23 Mnookin S. The panic virus. New York, NY: Simon & Schuster;
2011.
24 Akehurst C. France suspends hepatitis B immunisation for
adolescents in schools. Euro Surveill 1998; 2: pii=1143.
25 Viral hepatitis prevention board. Multiple sclerosis and hepatitis B
vaccine? Meeting report. Vaccine 1999; 17: 2473–75.
26 Global Advisory Committee on Vaccine Safety (GAVCS), WHO
Secretariat. Global safety of vaccines: strengthening systems for
monitoring, management and the role of GACVS.
Expert Rev Vaccine 2009; 8: 705–16.
27 Jenny Mccarthy joins the defense of Andrew Wakefi eld. http://www.
liquida.com/article/15670682/andrew-wakefi eld-autism-jenny-
mccarthy (accessed March 30, 2011).
28 Facebook. Press room. http://www.facebook.com/press/info.
php?statistics (accessed March 28, 2011).
29 Kirby D. Evidence of harm mercury in vaccines and the autism
epidemic: a medical controversy. New York: St Martin’s Press, 2005.
30 Offi t PA. Deadly choices: how the anti-vaccine movement threatens
us all. New York, NY: Basic Books, 2011.
31 Mudur G. Anti-vaccine lobby resists introduction of Hib vaccine
in India. BMJ 2010; 340: c3508.
32 Peters RG, Covello VT, McCallum DB. The determinants of trust
and credibility in environmental risk communication: an empirical
study. Risk Anal 1997; 17: 43–54.
33 Pidgeon N, Kasperson R, Slovic P, eds. The social amplifi cation
of risk. Cambridge: Cambridge University Press, 2003.
34 Centers for Disease Control and Prevention. Thimerosal in
vaccines: a joint statement of the American Academy of Pediatrics
and the public health service. http://www.cdc.gov/mmwr/preview/
mmwrhtml/mm4826a3.htm (accessed March 10, 2011).
35 Schechter R, Grether JK. Continuing increases in autism reported
to califronia development services system: mercury in retrograde.
Arch Gen Psychiatry 2008; 65: 19–24.
36 Fombonne E. Thimerosol disappears but autism remains.
Arch Gen Psychiatry 2008; 65: 15–16.
37 United Nations Educational, Scientifi c and Cultural Organization.
The precautionary principle. World Commission on the ethics of
scientifi c knowledge and technology (COMEST). Paris: COMEST,
2005.
38 Centers for Disease Control and Prevention. Impact of of the 1999
AAP/USPHS joint statement on http://www.cdc.gov/mmwr/
preview/mmwrhtml/mm4826a3.htm (accessed on March 10, 2011).
39 Lone Z, Puliyel JM. Introducing pentavalent vaccine in the EPI
in India: a counsel for caution. Indian J Med Res 2010; 132: 1–3.
40 Puliyel J. India cannot aff ord to use vaccines that are not
cost-eff ective. The Guardian (London) Oct 27, 2010.
41 Puliyel J, Mathew JL, Priya R. Incomplete reporting of research
in press release: Et tu, WHO? Indian J Med Res 2010; 131: 588–89.
42 Puliyel JM. GAVI and WHO: demanding accountability. BMJ 2010;
341: 266.
43 John J, Bose A, Balraj V. Misrepresenting data: deception or dogma?
Indian J Med Res 2010; 132: 463–65.
44 Saxena KB, Banerji D, Qadeer I, et al. “Antivaccine lobby” replies
to the BMJ. BMJ 2010; 341: c4001.
45 Murch SH, Anthony A, Casson DH, et al. Retraction
of an interpretation. Lancet 2004; 363: 750.
46 Wright JA, Polack C. Understanding variation in measles-mumps-
rubella immunization coverage— a population-based study.
Eur J Public Health 2006; 16: 137–42.
47 UK National Health Service. Increase in MMR vaccination coverage
in England, report shows, but child immunisation levels are still
lower than the rest of the UK. http://www.ic.nhs.uk/news-and-
events/news/increase-in-mmr-vaccination-coverage-in-england-
report-shows-but-child-immunisation-levels-are-still-lower-than-the-
rest-of-the-uk (accessed May 15, 2011).
48 Vaccine liberation army. http://vaccineliberationarmy.com/
our-hero-dr-andrew-wakefi eld-on-the-today-show-2
(accessed May 15, 2011).
49 Vitamin lawyer health freedom blog. http://vitaminlawyer
healthfreedom.blogspot.com/2010/04/dr-andrew-wakefi eld-
medical-hero.html (accessed May 15, 2011).
50 Milstein J, Griffi n PD, Lee J-W. Damage to immunisation
programmes from misinformation on contraceptive vaccines.
Reprod Health Matters 1995; 3: 24–28.
51 UNICEF. Combatting antivaccination rumours: lessons learned from
case studies in east africa. Nairobi: Eastern and Southern Africa
UNICEF Regional Offi ce. http://www.path.org/vaccineresources/
fi les/Combatting_Antivac_Rumors_UNICEF.pdf (accessed
March 27, 2011).
52 Stephens J. Pfi zer to pay $75 million to settle trovan-testing suit.
Washington Post (Washington, DC), July 31, 2009.
53 CDC wild poliovirus type 1 and type 3 importations—15 countries
in Africa, 2008–2009. MMWR 581: 357–62.
Series
www.thelancet.com Vol 378 August 6, 2011
535
54 WHO. Polio virus respects no borders. http://www.searo.who.int/
LinkFiles/Advocacy_Eff orts_Polio_virus_respects_no_borders_
Aug07.pdf (accessed Dec 15, 2010).
55 Global Polio Eradication Initiative. Report by the WHO Secretariat
to the 60th World Health Assembly. Poliomyelitis: mechanism for
management of potential risks to eradication. http://www.
polioeradication.org/content/general/WHA61_Resolution_English.
pdf (accessed Dec 15, 2011).
56 Taylor S, Shimp L. Using data to guide action in polio health
communications: experience from the Polio Eradication Initiative
(PEI). J Health Commun 2010; 15: 48–65.
57 Closser S. Chasing polio in Pakistan: why the world’s largest public
health initiative may fail. Nashville: Vanderbilt University Press,
2010.
58 Chaturvedi S, Dasgupta R, Adhish V, et al. Deconstructing social
resistance to pulse polio campaign in two north indian districts.
Indian Pediatrics 2009; 46: 963–74.
59 Galazka AM, Robertson SE, Oblapenko P. Resurgence
of diphtheria. Eur J Epidemiol 1995; 11: 95–105.
60 Gangarosa EJ, Galazka AM, Wolfe CR, et al. Impact of anti-vaccine
movements on pertussis control: the untold story. Lancet 1998;
351: 356–61.
61 Parry J. No vaccine for the scaremongers. Bull World Health Organ
2008; 86: 425–26.
62 Martin R. Lessons learned from SIAs: magnifi cation of the
opportunities and risks to routine immunization programmes.
4th Annual Global Immunization Meeting; New York, NY, USA;
Feb 19, 2009.
63 McAlister A, Puska P, Salonen J, et al. Theory and action for health
promotion: illustrations from the North Karelia project.
Am J Public Health 1982; 72: 1.
64 Flynn J, Burns W, Mertz CK. Trust as a determinant of opposition
to a high-level radioactive waste repository: analysis of a structural
model. Risk Anal 1992; 12: 417–29.
65 Alesina A. Who trusts others? J Public Econ 2002; 85: 207.
66 Das J, Das S. Trust, learning, and vaccination: a case study
of a north Indian village. Soc Sci Med 2003; 57: 97–112.
67 Savage I. Demographic infl uences on risk perceptions. Risk Anal
1993; 13: 413.
68 Fowler GL, Kennedy A, Leidel L, et al. Vaccine safety perceptions
and experience with adverse events following immunization in
Kazakhstan and Uzbekistan: a summary of key informant
interviews and focus groups. Vaccine 2007; 25: 3536–43.
69 Bedford H, Elliman D. Concerns about immunisation. BMJ 2000;
320: 240.
70 Streefl and PH. Public doubts about vaccination safety and
resistance against vaccination. Health Policy 2001; 55: 159–72.
71 Wroe AL, Bhan A, Salkovskis P, Bedford H. Feeling bad about
immunising our children. Vaccine 2005; 23: 1428–33.
72 Streefl and P, Chowdhury AMR, Ramos-Jimenez P. Patterns
of vaccination acceptance. Soc Sci Med 1999; 49: 1705–16.
73 Stern PC, Feinberg HV, eds. Understanding risk: informing
decisions in a democratic society. Washington, DC: National
Research Council, National Academy Press, 1996.
74 Pidgeon N, Fischhoff B. The role of social and decision sciences
in communication uncertain climate risks. Nat Clim Chang 2011;
1: 35–41.
75 Freed GL, Clark SJ, Butchart AT, Singer DC, Davis MM. Parental
vaccine safety concerns in 2009. Pediatrics 2010; 125: 654–59.
76 Covello VT. Best practices in public health risk and crisis
communication. J Health Commun 2003; 8 (suppl 1): 5–8.
77 Project to support public confi dence in immunization programs.
http://www.lshtm.ac.uk/eph/ide/research/vaccinetrust
(accessed April 19, 2011).
78 Andrus JK, Toscano CM, Lewis M, et al. A model for enhancing
evidence-based capacity to make informed policy decisions on the
introduction of new vaccines in the americas: PAHO’s PRPVAC
Initiative. Public Health Rep 2007; 122: 811–16.
79 Bingham A, Janmohamed A, Bartolini R, et al. An approach to
formative research in hpv vaccine introduction in low-resource
settings. Open Vaccine J 2009; 2: 1–6.
