Module 3 – Immunization
Vaccines are one of the public health interventions that have had the greatest
impact on the world’s health. A handful of vaccines prevent illness or death for millions
of individuals every year. Smallpox has been eradicated, poliomyelitis has been
eliminated from the Western Hemisphere, and measles cases in the U.S. have reached a
record low. However, vaccines are under-utilized so there is still a long way to go. In
the U.S., only 73% of children are fully immunized. The rates of influenza and
pneumococcal immunization for adults are even lower. Worldwide, almost 2 million
children die each year from diseases for which vaccines are available. Over 90,000
children worldwide still fall victim to paralytic polio; most of these cases could be
prevented by immunization. Better utilization of existing vaccines is one strategy to
improve the health of the nation and the world.
New vaccines offering protection against other pathogens are continually being
developed and tested. Two of the greatest challenges in vaccine science are the
development of effective vaccines for HIV and malaria. Even if such vaccines become
available, effective vaccination strategies will be necessary to achieve good compliance
and fully realize their potential.
Physicians should be aware of current recommendations for common immunizations,
geographic and demographic variations in immunization rates, barriers to effective
vaccination programs, on-line references for the proper use of other vaccines, actual data
and misconceptions about vaccine side effects, and what types of vaccinations to expect
in the future. These and other issues will be explored in this module.
I.
Learning Objectives for the Immunization Module
1. Recognize that immunization rate is one of our leading health indicators.
2. Understand how immunization rates vary among different geographic,
socioeconomic and ethnic groups.
3. Recognize the impact vaccinations have had on mortality rates in the U.S.
4. Review the current guidelines for immunizing children and adults.
5. Be aware of adverse events that are known to be associated with
vaccination and the relative frequency of these events. Recognize those
adverse events the public believes to be associated, and the status of
investigations into those claims.
6. Understand how immunizations impact your health expectancy and life
expectancy.
7. Convert the concerns about the possibility of vaccine side effects into
answerable questions and utilize the medical literature or evidence-based
medicine repositories to answer them.
8. Identify case reports (or case series) studies, case control studies, and
cohort studies. Recognize the relative value of evidence from each of
these study types.
9. Discuss the ethical issues of mandatory vaccination in order to attend
school. Are there legal precedents?
II.
Instructions
A. Read the following articles or chapters prior to the session.
1) The History of Vaccination
http://www.who.int/vaccines-diseases/history/history.shtml/htm
2) Ada, Gordon; Vaccines and Vaccination; N Eng J Med, 2001 345(14): 1042–
53.
3) Healthy People 2010 Chapter 14 Immunization and Infectious Diseases
http://www.healthypeople.gov/Document/tableofcontents.htm#under. Read the
introduction and the sections pertaining to vaccination (sections 14-1 through 148 and 14-22 through 14-31.)
B. Discuss the following case vignettes during the forum. After this session,
everyone in the group should be able to answer the questions at the end of
each vignette.
Case 1
A mother brings her 12-month old boy to your office for a well baby visit.
He has not had any serious problems since his previous visit at 9-months.
You discuss the baby’s feeding, sleeping, and behavior with the mother.
A general physical exam is normal. You review the chart and see that he
has received two doses of hepatitis B vaccine, three doses of DtaP vaccine,
two doses of HiB vaccine, and three doses of inactivated polio vaccine, all
on schedule. You have previously given Vaccine Information Sheets to
the mother. You mention that the baby should receive his first MMR
vaccine today. The mother is visibly uncomfortable at this suggestion.
You sense her unease and ask her what is wrong. She says that she has
been reading about MMR and has heard that it might cause autism in some
cases. Furthermore, she feels that it is really not necessary to get the
immunization, because these diseases are now quite rare.
1.
2.
3.
4.
5.
Specifically, what would you say to the mother?
What is the evidence for linking MMR vaccine to autism?
What are some other common misconceptions about vaccines?
How are adverse effects of vaccines reported?
How are patients who suffer adverse effects from a vaccine
compensated?
(To answer these questions it may be helpful to consult the CDC’s
National Immunization Program website http://www.cdc.gov/nip/. Look at
‘Common Misconceptions’ about vaccination; the reporting site for
adverse effects (VAERS); the Vaccine Injury Compensation Program
(VICP); Vaccine Information Statements (VIS) and look for information
about vaccines and autism. For more information on how to handle
patients like this, go to the National Network for Immunization
Information website http://www.immunizationinfo.org/. Look at
information on communicating with patients (in the section for health
professionals). The brief article “When Parents Resist Immunizations”
may be helpful.
Case 2
A 50-year old man is planning to make the Hajj (a pilgrimage to Mecca,
Saudi Arabia) in March of next year. He comes to your office asking
about vaccinations and other prophylaxis that he should take for safe
travel. He is your patient but it has been 18 months since you last saw
him. He has been without complaints. He has a history of hypertension
for which he takes a beta-blocker twice per day. He has had no major
illnesses, no surgeries, and no hospitalizations. He has no allergies.
1. What other aspects of the history are important to obtain?
2. List the specific vaccines you will recommend.
3. When will you administer these vaccines and how will you advise him
about side effects?
4. Are any laboratory tests required before he begins the vaccinations you
advise?
5. Is there additional counseling you will provide to help ensure a safe
trip?
(To answer these questions it will be useful to consult the CDC website
www.CDC.gov and look in the Travelers’ Health section)
Case 3
A 17-year old girl is preparing to go to college in the fall. She has no
major medical illnesses and has never been hospitalized. She will be
living in a dormitory. She read about a vaccine that prevents
meningococcal meningitis. She is wondering whether or not she should
get this vaccine.
1. How will you advise her?
2. Should all college freshmen receive meningococcal vaccine?
3. What is the evidence for or against widespread use of this vaccine?
(To answer these questions it will be useful to consult the CDC’s National
Immunization Program website http://www.cdc.gov/nip/ and look at the
ACIP recommendations. Use this as a starting point; there are conflicting
views on this subject.)
C. Discuss the following multiple-choice questions
1.
Investigators attempted to assess the efficacy of the pneumococcal vaccine
in adults 65-years of age and older. They had access to a HMO database of
47,000 adults in this age group that dated back to 1995. At that time, 26,000 had
received the 23 valent pneumococcal vaccine and 21,000 had not. They were able
to track all cases of invasive pneumococcal disease in this population between
1995 and 1999 and correlated these cases with the patient's prior vaccination
status. They calculated the relative risk of invasive pneumococcal disease in the
vaccinated group to be .58.
This is an example of a
A)
B)
C)
D)
Case-control study
Case series
Prevalence survey
Retrospective cohort study
2.
Investigators studied the relationship between autistic disorders in children
and prior immunization with MMR vaccine. They calculated the incidence of
autism in vaccinated children and in unvaccinated children.
Which of the following results would suggest that vaccination with MMR
is a risk factor for the development of autistic disorder?
A) A relative risk of 0.92 in the vaccinated group.
B) An attributable risk of minus 3 per 1,000 person-years in
the vaccinated group
C) A relative risk of 2.5 in the vaccinated group.
D) An attributable risk of 0 per 1,000 person-years in the
vaccinated group
3.
Most people infected with West Nile virus (WNV) have only minor
symptoms (or remain a symptomatic). Data from cross-sectional surveys in
epidemic areas suggest that for every person hospitalized with serious illness
(meningitis or encephalitis) approximately 150 people have been infected with the
virus. In the first three years of the U.S. epidemic, 178 persons were hospitalized
with serious illness and there were 18 deaths. Your best estimate of the case
fatality rate for WNV infection is
A)
B)
C)
D)
Greater than 10 %
10%
0.66% (1 in 150)
0.066% (1 in 1500)
D. Special topics for discussion
Study Topic #1: Successes and Problems with Childhood Immunization
1. List the current recommendations for childhood vaccinations in the U.S.?
http://www.health.gov/healthypeople/Document/HTML/Volume1/14Immunization.htm
The Healthy People 2010 chapter on Immunization has a nice overview presentation about vaccine
use and vaccine preventable diseases.
2. Examine the current rates of childhood immunization. Are there differences
based on socioeconomic status, ethnicity, and geography? Where is does
Louisiana rank compared to other states?
http://www.cdc.gov/nip/data/default.htm
Data from the National Immunization Survey shows rates of various vaccines by state,
socioeconomic status, and ethnicity. Go to Immunization coverage in the U.S. and look at the
NIS Data. Find the most recent data and look at the tables.
3.
Cite examples of outbreaks of vaccine preventable childhood diseases in a
community (e.g. you may want to discuss the St. George, Utah measles outbreak of 1996
http://www.cdc.gov/mmwr/preview/mmwrhtml/00049048.htm or similar outbreaks). Find
and discuss at least one primary journal article that attempts to establish a causal
association between such an outbreak and reduced vaccination rates among
community members. Describe the study design(s); was it appropriate to answer
the question posed? Discuss the findings. Discuss the possible consequences of
reduced vaccination rates in a community.
4.
Briefly discuss the legal and ethical issues surrounding mandatory vaccination for
school eligibility.
Study Topic #2: Parental Concerns about Vaccinations
1. Cite some common misconceptions about the risks of childhood vaccinations (use
the CDC website referenced above to start). Show examples of websites that
provide misinformation about childhood vaccinations (some examples are
suggested below, you may want to find others.)
http://www.thimerosalautism.com/
http://www.vaccine-side-effects.com/
As examples, these are a law firm’s network pages looking for thimerosal injury claims.
2. Briefly discuss the documentation of adverse effects from childhood vaccines (see
1994 IOM report and FDA-CDC vaccine injury reporting system - VAERS).
Describe the reporting process and its limitations. Are all of the reported adverse
events related to the vaccine in question? Cite some estimates of the rate of
adverse events with MMR, DaPT, OPV, and hepatitis B vaccines.
http://www.vaers.org/info.htm
3. Briefly summarize the theoretical arguments suggesting a link between MMR and
autism and the arguments about problems with thimerosal. Evaluate the evidence
for these claims.
You may want to look at recent Institute of Medicine reports on vaccine safety
(http://www.iom.edu/). Read the summaries of these reports for an overview.
4. Find and discuss some recent studies evaluating the association between autism
and MMR vaccine or thimerosal. Describe the study design(s); was it appropriate
to answer the question posed? Discuss the findings.
You may want to begin by searching comprehensive sites about autism and MMR with many links
and citations of recent studies. However, some recent studies may not be referenced on these
sites.
http://www.cdc.gov/nip/vacsafe/concerns/autism/
http://www.aap.org/profed/thimaut-may03.htm
Study Topic #3: Problems and Successes in Adult Immunization
1. Briefly review current ACP (American College of Physicians) guidelines for adult
immunization (use of influenza, pneumococcal, hepatitis [A and B] vaccines and
tetanus booster, etc).
http://www.acponline.org/aii/vaccine_info.htm
This site discusses each vaccine and lists the recommendations on their use by the ACP. You can
also find these recommendations on the CDC’s National Immunization Program site.
2. Briefly describe the consequences of influenza (morbidity and mortality). What
percent of those who meet the criteria for influenza vaccination are actually
immunized? Are there particular socioeconomic, ethnic, or geographic areas of
concern?
http://www.stanford.edu/group/virus/uda/
http://www.cdc.gov/flu/
These sites provide some information about influenza and its consequences. One site describes
the great pandemic of 1918.
Data on the use of the influenza vaccine can be obtained from the National Health Interview
Survey by the National Center for Health Statistics.
http://www.cdc.gov/nchs/about/major/nhis/released200306.htm
3. Briefly describe the epidemiology of pneumococcal disease in this country.
Describe the pneumococcal vaccine and discuss its use. How efficacious is it and
does it protect against all strains of S. pneumoniae? Is there good evidence for its
efficacy? What is its role in protecting the splenectomized individual? What
percentage of eligible adults receives the pneumococcal vaccine? Are there
particular socioeconomic, ethnic, or geographic areas of concern?
http://www.cdc.gov/nip/diseases/pneumo/default.htm
This site has links to several texts that discuss pneumococcal disease and the available vaccines.
The National Center for Health Statistics site above also has information about the use of
pneumococcal vaccine.
4. Discuss the potential problem of “avian flu”. How should we handle this from a
public health perspective?
Study Topic #4: Vaccination to Protect Against Agents of Bioterrorism
1.
Briefly discuss the CDC classification system for bioterror agents. What is meant
by a category A agent?
2.
List and briefly describe the six agents that pose the greatest risk to the U.S.
population (category A agents). Describe the illness caused by each organism
(including mortality rates) and its potential for use as an agent of bioterrorism
(including modes of transmission).
3. For which of these agents does a vaccine exist? Describe the Anthrax and
Smallpox vaccines. How is each administered and what are the side effects?
How protective are these vaccines? What are the current recommendations for
the use of each?
Most of these questions can be answered using the CDC’s Public Health Emergency Preparedness
website http://www.bt.cdc.gov and the Johns Hopkins Center for Civilian Biodefense Strategies
website http://www.hopkins-biodefense.org/
4.
Find and discuss recent studies evaluating the possible outcomes of a smallpox
attack. Describe the study design; was it appropriate to answer the question
posed? Discuss the findings and their implications for policy decisions regarding
smallpox vaccination.