Vaccine Opposition and Hesitancy

19CHAPTER 3

vaccine-hesitant patients and ensuring that they have enough time to

ask questions and make decisions before vaccines are due.

HCPs should ensure that a vaccine recommendation is followed by

vaccination. Providers who recommend vaccines but do not vaccinate

at the point of care should inform patients where they can be vaccinated. This discussion may include information about public health

clinics, travel clinics, and pharmacies or a referral to another provider.

HCPs should follow up with their patients at subsequent appointments

to confirm that they were vaccinated.

Adverse Events Following Vaccination Although rare, adverse

events (Chap. 123) may influence vaccine acceptance and willingness

to be vaccinated in the future. It is important for providers to identify and follow up with all patients who experience an adverse event,

regardless of the patients’ vaccine attitudes prior to the event. Adverse

events following vaccination should be reported to the relevant vaccine

monitoring system: the U.S. Vaccine Adverse Event Reporting System

or the Canadian Adverse Event Following Immunization Surveillance

System.

Addressing Inequities In Vaccine Access Discrepancies in

access to health care services create inequitable access to vaccines

for children and adults and contribute to under-vaccination. A U.S.

study found that socially disadvantaged individuals were more likely

than other persons to be under-vaccinated, in part because of a lack

of access to health care services. HCPs must recognize that socially

disadvantaged individuals and populations are often at greater risk of

vaccine-preventable diseases (e.g., as a result of crowded living conditions, limited access to sanitation, poor nutrition, or substance abuse)

and also at greater risk of being under-vaccinated because they have

limited access to health care services. In addition, specific vaccines may

be recommended for some socially disadvantaged populations or communities. For example, in the wake of several outbreaks of hepatitis A

among the U.S. homeless population, the CDC now recommends that

everyone >1 year of age experiencing homelessness receive hepatitis A

vaccine.

Depending on the setting and the patient, some recommended vaccines may not be covered through public funding or private insurance

coverage. HCPs should be aware of alternative funding models, such

as the Vaccines for Children Program, which provides free vaccines

for U.S. children (<19 years of age) with financial barriers to vaccine

access. When vaccines are not publicly funded or covered by private

insurance and patients perceive that they cannot afford a vaccine,

HCPs should not withhold a vaccine recommendation. The risks and

benefits of vaccination still need to be communicated, with a strong

recommendation, and the patient should be provided the opportunity

to decide whether they can afford the vaccine.

Further Communication With Patients Who Refuse Vaccines

Fortunately, the proportion of people who completely refuse all vaccines and are not willing to talk to their HCP is small. Nevertheless, in

some cases, attempts to initiate discussion and address vaccine refusal

may be futile. When possible, HCPs should focus on the common

goals of care and preserve the therapeutic relationship. Vaccine refusal

should be well documented in the patient’s chart. The HCP should continue with tailored communication and be open to future discussions.

Vaccine demand and vaccine refusal are rarely static over time. (See

“Focus: COVID-19 Vaccine Hesitancy,” below.)

■ CONCLUSION

In summary, vaccine hesitancy is complex and context specific. It

varies with time, place, patient, and vaccine. HCPs are well positioned

to address vaccine hesitancy and should develop the skills, knowledge,

and confidence to make strong vaccine recommendations to their

patients.

■ FOCUS: COVID-19 VACCINE HESITANCY

As COVID-19 vaccines are used to control SARS-CoV-2, some individuals will have concerns about these vaccines and a proportion of

the population will reject them. While worrisome, hesitancy about

COVID-19 vaccines is not unexpected; it mirrors public concerns

expressed about past pandemic influenza vaccines and other newly

introduced vaccines. It has been established that the newness of

any vaccine, be it a pandemic influenza vaccine or a COVID-19

vaccine, raises concern in a large percentage of the population. Politicization of COVID-19 vaccines raises additional issues for some

patients.

Past Experience with New Vaccines Past experience with new

vaccines, including the H1N1 pandemic influenza vaccine in 2009 and

the human papillomavirus vaccine in the early 2000s, provides a guide

to topics that need to be addressed with regard to COVID-19 vaccines.

While resistance is often framed as uncertainty about a vaccine’s “newness,” further discussion translates this uncertainty into concern about

the new vaccine’s safety. This concern encompasses both short- and

long-term side effects. Frequent, acute adverse effects can be captured

in clinical trial data, whereas worries about rare and long-term side

effects can be addressed only by direct evidence after the initiation of

a new vaccination program. In addition to queries about the overall

safety of the vaccine, HCPs can expect specific questions regarding the

safety of individual ingredients included in the vaccine, whether or not

these ingredients are new and whether or not relevant safety data are

available. Information on the incidence of common or expected health

events in an unvaccinated population (i.e., background rates) over a

4-week period is helpful in distinguishing what is normal and expected

from a point of concern. Studies that have examined this issue with

regard to other vaccines can be used as a basis for presenting background rates of expected events in the context of COVID-19 vaccines

for some groups; however, it is important to ensure that more specific

background-rate information is available to HCPs with regard to the

individual groups being vaccinated. HCPs, public health programs,

and vaccine manufacturers can anticipate these questions and should

develop answers and information to respond to them.

Specific Concerns about COVID-19 Vaccines While some

concerns can be anticipated on the basis of past experience with new

vaccines, several characteristics of COVID-19 vaccines require new

approaches to adequately address individual concerns, and HCPs need

to educate themselves in several specific areas. First, an overwhelming amount of attention has been paid to the speed of development

of COVID-19 vaccines, with some jurisdictions even skipping the

usual clinical-trial steps in an effort to provide vaccine more rapidly

to their populations. This situation directly increases concerns about

the “newness” of the vaccine and its safety and, unfortunately, raises

questions about the entire vaccine development process. Education is

required to explain how a process that normally requires 5–10 years

was condensed to this degree. (See Lurie et al [2020] for an excellent explanation of the COVID-19 vaccine development process.) In

addition, transparency with regard to clinical trial data is required to

enable scientists, HCPs, and consumers to read and understand the

development and evaluation processes. The usually shrouded, proprietary development process is unsuitable if the final vaccine product is

to garner public trust. Education on existing vaccine-safety monitoring

systems also needs to be provided. HCPs must familiarize themselves

with the vaccine development process and safety monitoring systems if

they are to present this information to their patients.

Second, several newer vaccine platforms that are being used for

COVID-19 vaccines (e.g., nucleic acid–based vaccines, viral vector)

have not been used in the past. This novelty exacerbates public concern about the unfamiliarity of new vaccines and further heightens

misgivings about vaccine safety and the potential for long-term adverse

effects. Again, HCPs need to familiarize themselves with the new technology and develop effective messaging for their patients. Public health

officials have developed resources to address this issue (see www.cdc.

gov/vaccines/covid-19/vaccinate-with-confidence.html), but, even in the

absence of such resources, HCPs can anticipate questions about the

new technology involved and become comfortable explaining it.

20PART 1 The Profession of Medicine

1

The Tuskegee Syphilis Study is the most infamous example of medical experimentation in Black communities in the United States. (See Brandt [1978]

for details.) Numerous examples of medical experimentation on Indigenous

peoples are available. For example, a 12-year trial of an experimental bacille

Calmette-Guérin vaccine for tuberculosis was conducted on Cree and Nakoda

Oyadebi infants in Saskatchewan during the 1930s. (See Lux [2016] for details.)

Third, clinical trial safety and efficacy data were lacking for all

groups initially prioritized to receive the vaccine. For example, longterm-care residents were prioritized for vaccine receipt, but clinical

trial data were not available for the range of chronic health conditions

that exist in older adults. While observational studies have filled some

of these gaps, HCPs need to extrapolate on the basis of available evidence in considering individual patients and must make a recommendation without knowing all the answers.

Fourth, some minority and marginalized communities who have

been disproportionately affected by COVID-19 express hesitancy or

reject COVID-19 vaccines. For some Black, Indigenous, Latinx, and

other communities, COVID-19 hesitancy stems directly from systematic discrimination, racism, and mistreatment in the health care

system. Black and Indigenous communities also share a horrific legacy

of unethical medical experimentation,1

 which, when combined with

current discrimination and overt racism, creates a powerful climate of

mistrust in HCPs, the medical system, and science.

Social and Cultural Trends The social and cultural trends

already discussed in this chapter—in particular, traditional media,

the Internet, and social media—are exerting influence and pressure

that did not affect the introduction of older vaccines, even the H1N1

pandemic vaccines. The media attention given to the development of

transverse myelitis in one clinical-trial participant following receipt of

COVID-19 vaccine is but one example of the intense media scrutiny

of the vaccine development process. Unfortunately, in the United

States, efforts to control COVID-19, including vaccine development,

have become highly politicized. This degree of politicization has not

occurred with past vaccines, so HCPs are in uncharted territory in

terms of how to address it or even to understand its potential influence

on vaccine acceptance. Again, individual HCPs need to navigate complex conversations with their patients and possibly their communities.

Below are some suggestions that may prove helpful in formulating

these conversations.

Tips for Discussion of COVID-19 Vaccines •  ADDRESS

CONCERNS ABOUT “NEWNESS” HCPs need to understand and be

able to explain the newer vaccine platforms (mRNA, DNA, and viral

vector vaccines) and to provide examples of other, older vaccines that

have been developed by similar techniques. This information makes

COVID-19 vaccines more familiar.

ADDRESS CONCERNS ABOUT VACCINE SAFETY HCPs need to understand and explain how vaccines are evaluated before being approved

for use and how vaccine safety is monitored after vaccines are used in

the population. It is important to be honest and state that potential rare

and long-term effects are not yet known, but then to speak to what is

from the animal and clinical trial data and to comment on background

rates for rare events. Placing potential vaccine risks in the context of

known COVID-19 disease risks is helpful for some patients.

Depending on the context, explain why specific high-risk groups

may have been prioritized to receive the vaccine. Patients who have

been prioritized may still need a strong recommendation from an HCP

to accept the vaccine. An HCP recommendation is as important here

as it is for acceptance of routine vaccines. As with other vaccines, many

patients’ decision to accept a COVID-19 vaccine rests upon whether

their HCP recommends it.

Address implicit or overt racism and systemic discrimination in the

medical system and create culturally safe health care spaces. HCPs

need to be aware of the legacy of discrimination, racism, and medical experimentation and the distrust it fosters in some communities.

While SARS-CoV-2 has critically highlighted fractures in our health

care system for minority and marginalized communities, addressing

these underlying issues goes beyond addressing vaccine hesitancy and

is clearly needed for all types of medical care in these communities.

EMPHASIZE THE IMPORTANCE OF KEEPING UP TO DATE WITH OTHER

ROUTINE VACCINES DURING THE COVID-19 PANDEMIC These vaccines include but are not limited to seasonal influenza vaccine and the

childhood primary vaccination series.

■ FURTHER READING

Vaccine Hesitancy

American Academy of Pediatrics: Vaccine hesitant parents.

Available at www.aap.org/en-us/advocacy-and-policy/aap-healthinitiatives/immunizations/Pages/vaccine-hesitant-parents.aspx.

Accessed October 23, 2020.

DeStefano F et al: Principal controversies in vaccine safety in the

United States. Clin Infect Dis 69:726, 2019.

Dudley MZ et al: The state of vaccine safety science: Systematic

reviews of the evidence. Lancet Infect Dis 20:e80, 2020.

Immunization Action Coalition: For healthcare professionals.

Available at www.immunize.org. Accessed October 23, 2020.

Immunization Action Coalition: For the public: Vaccine information you need. Available at vaccineinformation.org. Accessed October

23, 2020.

Jamison AM et al: Vaccine-related advertising in the Facebook Ad

Archive. Vaccine 38:512, 2020.

Leask J et al: Communicating with parents about vaccination: A

framework for health professionals. BMC Pediatr 12:154, 2012.

MacDonald N et al: Vaccine hesitancy: Definition, scope and determinants. Vaccine 33:4161, 2015.

World Health Organization: Vaccine hesitancy survey questions related to SAGE vaccine hesitancy. Available at www.who.int/

immunization/programmes_systems/Survey_Questions_Hesitancy.pdf.

Accessed October 23, 2020.

World Health Organization: Improving vaccination demand

and addressing hesitancy. Available at www.who.int/immunization/

programmes_systems/vaccine_hesitancy/en/. Accessed October 23,

2020.

World Health Organization: Missed opportunities for vaccination (MOV) strategy. Available at www.who.int/immunization/

programmes_systems/policies_strategies/MOV/en/. Accessed October

23, 2020.

COVID-19 Vaccine Hesitancy

Brandt AM: Racism and research: The case of the Tuskegee Syphilis

Study. Hastings Cent Rep 8:21, 1978.

Centers for Disease Control and Prevention: Vaccinate with

confidence: Strategy to reinforce confidence in Covid-19 vaccines. Available at www.cdc.gov/vaccines/covid-19/vaccinate-withconfidence.html. Accessed April 5, 2021.

Lurie N et al: Developing Covid-19 vaccines at pandemic speed.

N Engl J Med 382:21, 2020.

Lux MK: Separate beds: A history of Indian hospitals in Canada,

1920s–1980s. Toronto, University of Toronto Press, 2016.

Mosby I et al: Medical experimentation and the roots of COVID-19

vaccine hesitancy among Indigenous Peoples in Canada. CMAJ

193:E381, 2021.

Decision-Making in Clinical Medicine

21CHAPTER 4

Practicing medicine at its core requires making decisions. What makes

medical practice so difficult is not only the specialized technical

knowledge required but also the intrinsic uncertainty that surrounds

each decision. Mastering the technical aspects of medicine alone,

unfortunately, does not ensure a mastery of the practice of medicine.

Sir William Osler’s familiar quote “Medicine is a science of uncertainty

and an art of probability” captures well this complex duality. Although

the science of medicine is often taught as if the mechanisms of the

human body operate with Newtonian predictability, every aspect of

medical practice is infused with an element of irreducible uncertainty

that the clinician ignores at her peril. Although deeply rooted in

science, more than 100 years after the practice of medicine took its

modern form, it remains at its core a craft, to which individual doctors

bring varying levels of skill and understanding. With the exponential

growth in medical literature and other technical information and an

ever-increasing number of testing and treatment options, twenty-first

century physicians who seek excellence in their craft must master a

more diverse and complex set of skills than any of the generations that

preceded them. This chapter provides an introduction to three of the

pillars upon which the craft of modern medicine rests: (1) expertise in

clinical reasoning (what it is and how it can be developed); (2) rational

diagnostic test use and interpretation; and (3) integration of the best

available research evidence with clinical judgment in the care of individual patients (evidence-based medicine [EBM]).

■ BRIEF INTRODUCTION TO CLINICAL REASONING

Clinical Expertise Defining “clinical expertise” remains surprisingly difficult. Chess has an objective ranking system based on skill

and performance criteria. Athletics, similarly, have ranking systems

to distinguish novices from Olympians. But in medicine, after physicians complete training and pass the boards (or get recertified), no

tests or benchmarks are used to identify those who have attained the

highest levels of clinical performance. At each institution, there are

often a few “elite” clinicians who are known for their “special problemsolving prowess” when particularly difficult or obscure cases have baffled everyone else. Yet despite their skill, even such master clinicians

typically cannot explain their exact processes and methods, thereby

limiting the acquisition and dissemination of the expertise used

to achieve their impressive results. Furthermore, clinical virtuosity

appears not to be generalizable, e.g., an expert on hypertrophic cardiomyopathy may be no better (and possibly worse) than a first-year medical resident at diagnosing and managing a patient with neutropenia,

fever, and hypotension.

Broadly construed, clinical expertise encompasses not only cognitive dimensions involving the integration of disease knowledge with

verbal and visual cues and test interpretation but also potentially the

complex fine-motor skills necessary for invasive procedures and tests.

In addition, “the complete package” of expertise in medicine requires

effective communication and care coordination with patients and

members of the medical team. Research on medical expertise remains

sparse overall and mostly centered on diagnostic reasoning, so in

this chapter, we focus primarily on the cognitive elements of clinical

reasoning.

Because clinical reasoning occurs in the heads of clinicians, objective study of the process is difficult. One research method used for

this area asks clinicians to “think out loud” as they receive increments

of clinical information in a manner meant to simulate a clinical

encounter. Another research approach focuses on how doctors should

reason diagnostically, to identify remediable “errors,” rather than on

how they actually do reason. Much of what is known about clinical

4 Decision-Making in

Clinical Medicine

Daniel B. Mark, John B. Wong

reasoning comes from empirical studies of nonmedical problemsolving behavior. Because of the diverse perspectives contributing to

this area, with important contributions from cognitive psychology,

medical education, behavioral economics, sociology, informatics, and

decision sciences, no single integrated model of clinical reasoning

exists, and not infrequently, different terms and reasoning models

describe similar phenomena.

Intuitive Versus Analytic Reasoning A useful contemporary

model of reasoning, the dual-process theory distinguishes two general

conceptual modes of thinking as fast or slow. Intuition (System 1)

provides rapid effortless judgments from memorized associations

using pattern recognition and other simplifying “rules of thumb” (i.e.,

heuristics). For example, a very simple pattern that could be useful

in certain situations is “black woman plus hilar adenopathy equals

sarcoid.” Because no effort is involved in recalling the pattern, the

clinician is often unable to say how those judgments were formulated.

In contrast, Analysis (System 2), the other form of reasoning in the

dual-process model, is slow, methodical, deliberative, and effortful. A

student might read about causes of hilar adenopathy and from that list

(e.g., Chap. 66), identify diseases more common in black women or

examine the patient for skin or eye findings that occur with sarcoid.

These dual processes, of course, represent two exemplars taken from

the cognitive continuum. They provide helpful descriptive insights but

very little guidance in how to develop expertise in clinical reasoning.

How these idealized systems interact in different decision problems,

how experts use them differently from novices, and when their use can

lead to errors in judgment remain the subject of study and considerable

debate.

Pattern recognition, an important part of System 1 reasoning, is

a complex cognitive process that appears largely effortless. One can

recognize people’s faces, the breed of a dog, an automobile model, or

a piece of music from just a few notes within milliseconds without

necessarily being able to articulate the specific features that prompted

the recognition. Analogously, experienced clinicians often recognize

familiar diagnostic patterns very quickly. The key here is having a large

library of stored patterns that can be rapidly accessed. In the absence

of an extensive stored repertoire of diagnostic patterns, students (as

well as experienced clinicians operating outside their area of expertise

and familiarity) often must use the more laborious System 2 analytic

approach along with more intensive and comprehensive data collection

to reach the diagnosis.

The following brief patient scenarios illustrate three distinct patterns associated with hemoptysis that experienced clinicians recognize

without effort:

• A 46-year-old man presents to his internist with a chief complaint

of hemoptysis. An otherwise healthy, nonsmoker, he is recovering

from an apparent viral bronchitis. This presentation pattern suggests

that the small amount of blood-streaked sputum is due to acute

bronchitis, so that a chest x-ray provides sufficient reassurance that

a more serious disorder is absent.

• In the second scenario, a 46-year-old patient who has the same chief

complaint but with a 100-pack-year smoking history, a productive

morning cough with blood-streaked sputum, and weight loss fits

the pattern of carcinoma of the lung. Consequently, along with the

chest x-ray, the clinician obtains a sputum cytology examination and

refers this patient for a chest CT scan.

• In the third scenario, the clinician hears a soft diastolic rumbling

murmur at the apex on cardiac auscultation in a 46-year-old patient

with hemoptysis who immigrated from a developing country and

orders an echocardiogram as well, because of possible pulmonary

hypertension from suspected rheumatic mitral stenosis.

Pattern recognition by itself is not, however, sufficient for secure

diagnosis. Without deliberative systematic reflection, undisciplined

pattern recognition can result in premature closure: mistakenly jumping to the conclusion that one has the correct diagnosis before all the

relevant data are in. A critical second step, therefore, even when the

diagnosis seems obvious, is diagnostic verification: considering whether