Missing Information About Vaccine Safety

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Missing Information About Vaccine Safety
Vaccine Safety, Dealing with Uncertainty

• Martin G.
  Myers, MD
• October 11, 2007

2
Outline

• Background
• Impact of vaccines
• Community Immunity
• The Origins of Risk Benefit Misperceptions
• Out of sight, Out of mind
• Concerns about vaccine safety
• Missing Information
• Scientific Uncertainty (but PH decisions MUST
  still be made).
• The evolution to Misinformation
• Misinformation Has Adverse Consequences

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The Immunization Programs have had Incredible
Success

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Vaccine Disease Prevention-1
Disease Cases prior to Vaccine1 Year universal rec. Cases 20052 Cases 20063
Smallpox 48,164 Early 1900s 0 0
Diphtheria 175,885 Mid 1940s 0 0
Pertussis 147,271 Mid 1940s 26,6164 15,6324
Tetanus 1,314 Mid 1940s 27 41
Paralytic Poliomyelitis 16,316 1955 15 0
Measles 503,282 1963 66 58
Mumps 152,209 1967 314 6,584
Rubella 47,745 1969 11 11
Congenital 823 1 1
1CDC. 1999. MMWR 48243. 2 CDC. 2007. 542. 3CDC.
2007. MMWR 56(33). 4Cases of pertussis were at a
historic low of 1010 in 1976. 5Imported,
vaccine-associated.
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Vaccine Disease Prevention-2
Disease Cases/yr prior to Vaccine1 Year universal rec. Cases 20052 Cases 20063
Invasive6 H. influenzae, type b 20,000 1985 9 29
Invasive6 S. pneumoniae 89,400 2000 1495 1861
Hepatitis B (acute) 21,102 1991 5,119 4,713
Varicella 4,000,000 1995 32,242 48,445
deaths 115 3 NA8
Hepatitis A (acute) 26,796 19997/2006 4488 3579
6Children lt6 years of age. 7Recommended for
highest risk communities in 1996, for communities
and states with increased risk (1999) and then
for universal use (2006). 8Data not available.
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If vaccines have been such a great success,

• Why have there been recent outbreaks of measles
  in UK, Ireland, Germany, China, Japan, Korea,
  Mongolia, Italy, Switzerland, Belgium, Marshall
  Islands?
• Why do gt2000 children refuse immunization in New
  York?
• Why is immunization coverage higher in Mexico
  Canada than in than the US?
• Why do many communities permit low immunization
  coverage levels?
• Why does it matter?

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Community Protection Requires High Levels of
Immunization

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Community (Herd) Immunity Thresholds

The proportion of immune individuals that is
required to prevent sustained transmission of
infection
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Community (Herd) Immunity Thresholds

• Measles gt94
• Poliomyelitis 50-93 (following IPV, unknown)
• Diphtheria 85
• Mumps 86
• Pertussis 94
• Rubella 83-85
• Smallpox 80-85

After Fine P. in Orenstein Plotkin 4th Edition,
2004.
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Immunization Coverage ( immunized) is used as a
Surrogate Marker for Community Immunity

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US1, Mexico2, and Canada2 Vaccine Coverage for
19-35 month olds, 2006
USA Canada Mexico
Polio 92.9 94 98
DTP 85.2 94 98
HBV 93.6 73
Measles 92.4 94 96
Hib 93.4 94 73
PCV 87.0
VZV 89.3
1 www.cdc.gov/vaccines/stats-surv/nis/data/tables_
2006.htm 2 www.who.int/vaccines/global.
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Why are Under-Immunized Children so Important?

• The unimmunized children are at risk of disease.
• Those that can not be immunized are not
  protected.
• Those who are immunized may also be at risk,
  because no vaccine is 100 effective.
• For example, Measles
• the proportion of the population that needs to be
  immune to keep virus from transmitting person to
  person is 95 (but 5 remain susceptible after
  vaccination).
• If 2 are unimmunized, 5 more are also susceptible
  (5 of the 98) the immune level is about 93.
• In the US, MMR coverage is 92.4, immune level,
  therefore, is 87.8.

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Why are immunization coverage levels low in some
communities?

• There are Multiple Reasons
• Poverty.
• Disparities in access to healthcare.
• Fear of being identified by the government.
• Risk-benefit misperceptions.

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How Can Communities Knowingly Put Their Children
At Risk?!

• The key word is knowingly.
• One form of missing information is when
• The information is available, but unknown or
  unrecognized,
• For example, some communitiesand most parentsdo
  not recognize the risk to their community and
  their children from vaccine-preventable diseases.

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Missing Information

• The Lack of Community Understanding that their
  children are at Risk of harm from vaccine
  preventable diseases.
• Loss of diseases visibility.
• Loss of a sense of urgency.
• Lack of fear.
• The data are insufficient to support or reject
  the hypothesis.
• The uninformed/incompletely informed person may
  unintentionally disseminate misinformation.

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Misinformation

• The uninformed constitute the Unintentional
  Misinformers.
• Intentional Misinformers (disinformers) actively
  seek to mislead others.
• Some truly believe vaccines injured their child.
• Others seek personal gain.
• Misinformers have many sophisticated tools to
  disseminate misinformation.
• Media loves a controversy it makes the story
  interesting.
• The Internet is a powerful but also a dangerous
  source of information.
• Many persons are not worried about diseases they
  dont see (uninformed) and are confused about
  vaccine safety risk (misinformed).
• Most do not understand risk measurements.

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Information about Vaccines and Vaccine Safety

• Missing Information can Evolve into
  Misinformation

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The Evolution of Missing Information Into
Misinformation About Vaccine Safety Issues-1

• A vaccine safety concern is suggested
• The media may declare that there may be a
  problem.
• Some parents become confused.
• Scientists wont state that the vaccine did not
  cause the adverse eventbecause the information
  is insufficient (missing).
• This creates a sense of scientific uncertainty.
• Parents become confused.

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The Evolution of Missing Information Into
Misinformation About Vaccine Safety Issues-2

• Public health officials compare the possible
  risks from the adverse event of concern with the
  known risk of the disease, based on whatever
  available data there is.
• They must make recommendations to protect the
  public health, whether or not all the information
  is available.
• The media often report a controversy (meaning a
  difference of opinion) between public health
  officials and parents.
• True scientific controversy is rarely reported.
• Pseudoscience is discounted by scientists but
  often reported in the media.
• New data may become available that suggests a
  possible mechanism (but plausibility does not
  establish causality).
• Parents become confused.

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The Evolution of Missing Information Into
Misinformation About Vaccine Safety Issues-3

• With more data, scientists reach a consensus that
  the data favor rejection of the hypothesis-
  that is, the association is likely to be
  coincidental.
• Parents who are convincedplus intentional
  mis-informersstate that the science is in error
  they often try to discredit the scientists, etc.
• The media describes a controversy.
• Parents become confused.
• Outbreaks of disease may occur if vaccine
  coverage (community immunity) has declined.

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Measles-containing Vaccines and Autism

• Andrew Wakefield and MMR 27 February, 1998. Case
  reports.
• UK media reports
• Measles vaccine a possible cause of autism
• Reassurance by public health community.
• Data which takes many years to obtain does not
  find an association.
• The IOM Vaccine Safety Committee Report s the
  data favors rejection of an association (2004)
• Consequences
• MCV immunization levels drop and remain low in
  the UK ( several other countries).
• Measles outbreaks occur in the UK, Ireland,
  Germany
• Mumps outbreak occur in the UK (which spreads to
  US Canada)

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Measles-containing Vaccine Coverage UK
www.who.int/countries/global. Accessed Oct 5,
2007
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Cases of Measles UK
www.who.int/countries/global. Accessed Oct 5,
2007
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(No Transcript)
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Mumps Cases UK
www.who.int/countries/global. Accessed Oct 5,
2007
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Thimerosal Misinformation

• Despite many studiesand a careful review by the
  Institute of Medicine that favored rejection of
  the hypothesis
• The media continues to report a controversy.
• Children (10,000) are being treated with
  chelation therapy for mercury poisoning (one
  has died).
• Regions are reporting increasing delay of infant
  immunizations and numbers of children using
  school exemptions.
• We have reported increasing information seeking
  behavior temporally associated with major news
  stories about thimerosal misinformation.

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Compounding the Problem of Misinformation is our
use of Language
Expression/Word Technical Meaning Meaning to Public
Bias Systematic error Not an open mind
Controversy Differing interpretations of the same data Difference of opinion
Naïve Previously unexposed Unsophisticated
Plausible Theoretically possible Worthy of belief, factual
Safe Low risk No risk
Significant This may not be a chance difference Important
From Pineda D and Myers M. 2007. Do vaccines
cause that?! I4PH Press.