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Canadian Immunization Guide

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Part 1
Key Immunization Information 2013

Communicating Effectively about Immunization

Immunization is one of the safest and most effective interventions to prevent disease, morbidity and early death. Yet a portion of the population has concerns about vaccines and hesitates to get vaccinated or get their children vaccinated. Lower vaccination rates reduce the level of protection against a vaccine-preventable disease at a population level (i.e. herd immunity), potentially resulting in resurgence of vaccine-preventable diseases and associated complications. Most importantly, unvaccinated children are themselves at significantly higher risk of developing a vaccine preventable disease.

Over the past few years, there has been intense interest in understanding why people are unwilling to receive vaccines and how their concerns can be addressed to allow everyone to take part in vaccination programs. Effective communication by health care providers has an important influence on people’s decisions about whether or not to proceed with immunization.

This chapter reviews what is known about vaccine hesitancy, describes basic principles of effective communication, and provides examples of immunization facts.

Vaccine hesitancy

Vaccine hesitancy is a term used to describe refusal or delay in regular immunization schedules due to concerns about immunization. Vaccines evoke concerns different from other health interventions because they are largely intended for individuals who are healthy, as opposed to other health interventions that are predominantly intended for individuals with a disease. Vaccine hesitancy is a complex issue with multiple determinants, the most important being:

  • lack of information about the vaccine being given and about immunizations in general;
  • conflicting information from a variety of sources (e.g., alternative medicine practitioners, anti-vaccination websites);
  • mistrust of the source of information (e.g., perceptions of business and financial motives of the vaccine industry);
  • perceived risk of serious adverse events and concerns regarding injections (e.g., pain and anxiety associated with immunization; coincidental rather than causal adverse events that are perceived as vaccine-related);
  • lack of appreciation of the severity and incidence of vaccine-preventable diseases;
  • sociocultural beliefs (e.g. religious beliefs)

Loss of public confidence in immunization can reduce the number of people who are immunized and result in resurgence of vaccine-preventable diseases and associated complications. Evidence about the effects of misinformation, rumours, and anti-vaccine groups on vaccine coverage and consequent disease outbreaks in many countries is well documented.

The decision to immunize is a result of personal perceptions of complex vaccine and disease related information and the trust in individuals and institutions that produce, legislate, and deliver vaccines. Research identifies a number of factors that affect the extent to which an individual is trusted: perceptions of knowledge and expertise, openness and honesty, and concern and caring. Regular health care providers, such as vaccine providers, are perceived as trusted individuals and have a vital role in ensuring continued success of immunization programs and in maintaining confidence in the effectiveness and safety of vaccines. Besides demonstrating skills and expertise in the principles and practices of immunization, vaccine providers need to know how to counsel effectively and how to help vaccine recipients or parents knowledgeably assess the benefits and risks of immunization, as well as the risks associated with being unvaccinated.

Principles of effective communication

The majority of Canadians feel that they are well-equipped to make informed decisions about immunization. However, there are individuals who remain concerned about possible side effects of immunization and who require additional information to make evidence-based decisions. Vaccine providers should make the most of each opportunity to encourage questions, address misinformation, and provide valid and appropriate messages and resources, including websites that provide reliable information. The following principles can be used by vaccine providers to communicate immunization facts effectively (refer to Immunization Facts) to vaccine recipients or parents:

  • Adopt a vaccine recipient-centred approach.
    Vaccine recipients and parents should have input into the decision to immunize. Effective decision making is best done in a partnership between the vaccine provider, and the vaccine recipient or parent. Building these partnerships takes time and should ideally be established prior to the immunization visit. Vaccine providers should be transparent about the decision-making process, as well as honest and open about uncertainty and risks.

    Engaging and motivating vaccine recipients and parents are best accomplished through dialogue. Motivational interviewing is a semi-directive method aimed at changing behaviour. Additional information about motivational interviewing is available from the Public Health Agency of Canada - Motivational Interviewing – Motivating Patients to Adopt a Healthier Lifestyle.
  • Respect differences of opinion about immunization.
    Democratisation movements and the advent of the internet have changed the environment around immunization from top-down, expert-to-consumer communication, to non-hierarchical, dialogue-based communication. With the public increasingly questioning recommendations of experts and public institutions on the basis of their own, often web-based, research, vaccine providers should anticipate that individuals will question the need for, or the safety of, immunization. The majority of such individuals are not against immunization, but are seeking answers to questions about vaccine safety, immunization schedules, changing policies, and the relevance of some vaccines.

    In general, events that are unfamiliar, involve a man-made process, involve loss of control, are mandatory, or involve a decision to do something rather than avoid something, are perceived as risky. Immunization, therefore, is perceived by some individuals as a potential concern, particularly when it comes to immunizing children.

    Vaccine providers should determine the origins of vaccine hesitancy and take time to listen. Asking vaccine recipients or parents about their perceptions and discussing the benefits of immunization should be done using a non-judgemental and non-confrontational tone. Vaccine providers should clarify why a specific belief about a vaccine is held, especially if it is based on misinformation or misunderstanding. Demonstrating patience and respect builds trust and support for deciding to immunize. It is also important to recognize that, despite all the efforts taken, some individuals will not be persuaded into accepting vaccines.
  • Represent the risks and benefits of vaccines fairly and openly.
    Candidly communicating information about the safety of vaccines and their benefit–risk ratios is essential. For most individuals, vaccine safety is of primary concern and few are aware of Canada’s robust vaccine safety system or that vaccines are held to a higher safety standard than medications. This process includes comprehensive reviews of efficacy and safety data before approval, oversight over good manufacturing practices and quality before product release, expert review of vaccine recommendations, post-marketing surveillance and rapid response to vaccine performance concerns, and international collaboration. Vaccine providers need to outline the work that is done to assess vaccine safety during development, regulatory review, and on an ongoing basis following use of a vaccine. Refer to Vaccine Safety in Part 2 for additional information.

    Through direct dialogue and using language that is appropriate, vaccine providers should contrast the known and theoretical risks of vaccines with the known risks associated with the vaccine preventable diseases. Potential risks of any vaccine should not be considered in isolation but in comparison with risks to the individual and community should an individual remain unimmunized.

    Vaccine providers have a vested interest in the health of vaccine recipients. In addition to providing information, vaccine providers should provide immunization recommendations in accordance with their patients’ best interest. It is honest to express concern about the risks of vaccine preventable diseases should a person remain not vaccinated. It is also important to emphasize that, should vaccine preventable diseases occur, complications may not be correctable, even with the very best medical care. Refer to The Benefits of Vaccines in Part 1 for additional information.
  • Clearly communicate current knowledge using an evidence-based approach
    Vaccine providers should:
    • Assess the level and type of information that an individual wants and adapt the information provided accordingly; for example, some people will appreciate scientific evidence while others will prefer anecdotal information and stories from personal experience.
    • Present evidence in an understandable way; for example, concepts such as single event probability or relative risk may not be understandable for most vaccine recipients or parents; scientific jargon and acronyms should be avoided.
    • Frame immunization in terms of positive gains; for example, “A vaccine is 99% safe” is more effective than, “There is a 1% chance of side effects.” Similarly, “If you decide not to get the vaccine, you increase your chances of getting a disease,” is more effective than, “If you decide to get the vaccine, you decrease your chances of getting or transmitting a disease.”
    • Use and have available varied information formats (visual, audio, printed material, websites), tailored to a range of socio-cultural groups (i.e., educational level, language, ethnic and cultural background). It is estimated that 60% of adults and 88% of seniors in Canada are not health literate and have difficulty using the everyday health information that is routinely available. Additional information and resources about health literacy are available from the Public Health Agency of Canada and the Canadian Public Health AssociationExternal Link.
    • Inform vaccine recipients and parents about ways that they can make immunization less stressful (i.e., using combination vaccines and appropriate pain management strategies); pain and anxiety related to immunization are important factors in vaccine hesitancy. Refer to Vaccine Administration Practices in Part 1 for additional information about effective discomfort and anxiety reduction strategies.

Providing information does not need to be time-consuming, particularly given the volume and accessibility of material available on the internet. Refer to Guidance for parents on how to evaluate the accuracy of immunization informationExternal Link for more information regarding credible online sources for information about vaccines and immunization. Refer to Immunize CanadaExternal Link and Immunization Action CoalitionExternal Link for useful vignettes and personal stories concerning immunization.

Immunization facts

Vaccines work - immunization is the most effective way to protect against vaccine preventable diseases.

  • Vaccines are safe and effective; serious disease can occur if a person, their child and family are not immunized.
  • Immunization is one of the most important ways to promote health.
  • Over the past 50 years, immunization has saved more lives in Canada than any other health intervention.
  • Immunization protects both individuals who receive the vaccine and those with whom they come in contact, especially people who cannot be or are incompletely vaccinated due to medical conditions or age.
  • The World Health Organization estimates that every year, more than two million deaths are prevented worldwide due to immunization.
  • Immunization provides cost-savings to the individual and to the society.
  • Refer to The Benefits of Vaccines in Part 1 for additional information.

Vaccines strengthen the immune system.
Vaccines stimulate and strengthen the immune system. They train the immune system to defend rapidly against vaccine preventable infections before illness can occur.

  • The human immune system is continually challenged and has an enormous capacity to respond to antigens; infants can respond to about 10,000 different antigens at any one time. The few antigens in vaccines are tiny in comparison.
  • Children are naturally exposed to multiple antigens on a routine basis and they respond well to these ongoing exposures with no untoward effects on their immune system.
  • Immunization does not significantly add to the body’s daily exposure to antigens.

Vaccines are safe.

  • The vaccines used in Canada are highly effective and extremely safe. Vaccines are among the safest medical products available. Serious side effects, such as severe allergic reactions, are very rare.
  • Prior to authorization for use in Canada, vaccines are extensively tested and the manufacturer must submit scientific and clinical evidence that demonstrates the safety and efficacy of the vaccine.
  • Health Canada supervises all aspects of vaccine production by manufacturers to ensure safety, efficacy and quality. Vaccine safety continues to be rigorously monitored and evaluated after the vaccine is on the market.
  • Even after a vaccine has been authorized for marketing in Canada, every batch is laboratory tested for safety and quality.
  • Canada’s comprehensive vaccine safety monitoring system helps to alert public health authorities to trends in reported adverse events or any unusual adverse events not previously reported. Once a vaccine is in use, experts in vaccine safety conduct ongoing quality and safety monitoring, and investigate and respond to reports of serious adverse events following immunization. This system detects possible safety concerns associated with a vaccine so that appropriate action can be taken should such a concern arise.
  • Refer to Vaccine Safety in Part 2 for additional information.

The risks of vaccine preventable diseases are many times greater than the risk of a serious adverse reaction to a vaccine.

  • Serious adverse reactions are rare. The dangers of vaccine-preventable diseases are many times greater than the risks of a serious adverse reaction to the vaccine.
  • Diseases like polio, diphtheria, measles and pertussis (whooping cough) can lead to paralysis, meningitis, pneumonia, choking, brain damage, heart problems, and even death. Although today these diseases are non-existent or rare in Canada, if immunization programs were reduced or stopped, they would re-appear in epidemics causing sickness and death.
  • Effective treatments do not exist for many vaccine-preventable diseases.
  • In most cases, it is not possible to know in advance if an unvaccinated person will experience mild or severe complications from a vaccine-preventable disease.
  • The vast majority of vaccine adverse reactions are minor and resolve quickly.
  • Serious adverse reactions to vaccines are very rare and it is often very difficult to determine if a reaction was directly linked to a vaccine or was an unrelated event which only occurred by coincidence after the vaccine was administered.
  • Pre-vaccination screening is used to identify individual contraindications to administration of a vaccine and to reduce the risk of serious adverse reactions to a vaccine.
  • Vaccinees are observed post-vaccination for signs and symptoms of adverse reactions to a vaccine. Vaccine providers are familiar with the signs and symptoms of serious immediate allergic reactions to vaccines and are prepared to initiate management of the allergic reaction and administer appropriate medications.
  • Refer to The Benefits of Vaccines in Part 1 for additional information.

Vaccines are not linked to chronic diseases like autism, multiple sclerosis (MS), asthma, or sudden infant death syndrome.

  • Research using rigorous scientific methods has shown that:
    • Measles-mumps-rubella (MMR) vaccine does not cause autism
    • Thimerosal-containing vaccines do not cause autism
    • Hepatitis B vaccine does not cause multiple sclerosis (MS) or relapses of pre-existing MS
    • Pertussis vaccine does not cause brain damage
    • Vaccines do not cause sudden infant death syndrome
    • Childhood vaccines do not increase the risk of developing asthma
  • There is no evidence that any vaccine causes chronic diseases, autism or sudden infant death syndrome. Alleged links - for example between hepatitis B vaccine and multiple sclerosis - have been disproved by rigorous scientific study.
  • Refer to Vaccine Safety in Part 2 for additional information.

Multiple injections are an effective way of ensuring up to date immunization.

  • Multiple injections of vaccines do not overwhelm the immune system.
  • Generally, infants and children have similar immune responses whether vaccines are given at the same time or at different visits.
  • Giving several routine vaccines at the same visit does not result in increased rates of adverse reaction, compared to giving the vaccines at different visits.
  • Giving multiple vaccines at one visit helps to ensure that people are up to date with the vaccines required for their age and risk factors.
  • Delaying vaccines may leave a child or adult vulnerable to vaccine-preventable diseases.
  • Evidence has shown that multiple injections at one visit cause less pain than waiting a few days between administration.
  • Giving more than one vaccine at the same visit is critical when preparing for international travel or if there is uncertainty that a person will return for additional doses of vaccine.
  • Refer to Vaccine Administration Practices in Part 1 for additional information.

Vaccine preventable diseases can occur at any time because the bacteria and viruses that cause these infections have not been eliminated.

  • Bacteria and viruses that cause pneumonia, meningitis, diphtheria, pertussis, polio, measles, mumps, rubella, varicella, hepatitis A and hepatitis B are present in Canada or other parts of the world.
  • Even if a disease is uncommon in Canada, travellers can carry diseases from other countries to Canada. Outbreaks of measles in Canada have resulted from cases being imported.
  • Unless a disease has completely disappeared worldwide, there is a real risk that small outbreaks can turn into large epidemics if most of the community is not protected.
  • For some vaccine-preventable diseases, such as measles, one case in a community is a concern, because the disease spreads very quickly and easily among people who are not immune.
  • Clostridium tetani (tetanus or lockjaw) is widely distributed in soil – it will never be eliminated - so the risk of getting tetanus continues to exist for all people who are not immunized.
  • Haemophilus influenzae type b (Hib), Streptococcus pneumoniae (pneumococcal disease) and Neisseria meningitidis (meningococcal disease) are carried in the nose and throat of some healthy people, so these diseases continue to be a threat.

Unvaccinated individuals have a much greater chance of getting a vaccine-preventable disease than people who have been vaccinated, even in countries with high levels of immunization.

  • It may not be possible to avoid exposure to a vaccine-preventable disease. For example, an unvaccinated person can get measles by breathing the air in a room that was occupied hours before by a measles-infected person.
  • When disease is spreading in a community, a small percentage of vaccinated people may get sick; that is because no vaccine is 100% effective; however, a much larger percentage of unimmunized people exposed to the disease can become ill. In Canada in 2011, measles importations led to a large outbreak involving more than 700 people, largely in Quebec. Where immunization status was known, approximately 80% were not adequately immunized for their age.
  • Immunization can reduce the risk of severe disease if you do happen to get infected.
  • Refer to The Benefits of Vaccines in Part 1 for additional information.

Vaccine-preventable diseases re-appear quickly if immunization coverage drops.

  • In Japan, pertussis immunization coverage dropped from 90% to less than 40% because of public concern over two infant deaths following vaccination in 1975 (later found not to be caused by the vaccination). Prior to the drop in immunization, there were 200 to 400 cases of pertussis each year. Following the drop in immunization, surveillance data collected over a three year period showed that during this time the number of pertussis cases increased to approximately 13,000 and the number of deaths to over 100 per year.
  • In Ireland, measles immunization coverage dropped to 76%, following false allegations of a link with autism. In 2000, the number of measles cases increased from 148 to 1,200, and several children died due to the complications of measles.
  • The potential for re-emergence of diphtheria if immunization levels decline was demonstrated during the 1990s in the Commonwealth of Independent States (former Soviet Union) when over 140,000 cases and 4,000 deaths were reported.

Vaccines may contain additional substances to ensure effectiveness and safety – these substances are safe.

  • The main ingredients of vaccines are killed or weakened viruses or bacteria or their parts. These are called antigens and they train the immune system to recognize and prevent disease.
  • Additional substances may be required in the vaccine to ensure effectiveness and safety:
    • Very small amounts of preservatives, such as phenol, 2-phenoxyethanol or thimerosal, may be added to a vaccine to prevent the growth of microbes in the vaccine when it is used.
      • Thimerosal contains a minute amount of one form of mercury which does not accumulate in the body as other forms of mercury can. Current routine childhood vaccines in Canada do not contain thimerosal (with the exception of certain influenza and hepatitis B vaccines).
      • Vaccines do not contain anti-freeze, despite allegations by some opposed to immunisation.
    • Adjuvants, such as aluminum salts and squalene, may be added to strengthen the immune response to the vaccine. Without an adjuvant, people might require more frequent or higher doses of vaccines to be protected.
      • Aluminum is found in air, food and water and is present in breast milk and infant formula in similar amounts as in vaccines. Hundreds of millions of people have been safely vaccinated with aluminum-containing vaccines.
      • Squalene is a naturally occurring substance often found in plants, animals and humans, as well as foods and cosmetics. It is a compound produced by the liver and circulates throughout the bloodstream.
    • Additives, such as gelatin, human serum albumin or bovine reagents, are added to vaccines to help vaccines remain effective while being stored.
      • Gelatin in vaccines very rarely causes severe hypersensitivity reactions (approximately 1 case per 2 million doses). Individuals with a history of immediate allergic reactions to foods containing gelatin or who have had an anaphylactic reaction to any of the products containing gelatin should be referred to an allergist prior to vaccination.
      • Human serum albumin: there is an extremely small theoretical risk of infectious agents being present in products made from human blood. However, steps in the manufacturing process of both human albumin and human albumin-containing vaccines eliminate the risk of transmission of these agents. There have been no documented cases of vaccine-related transmission of infectious agents by human serum albumin.
      • In Canada, the bovine-derived reagents added to vaccines included in the routine immunization schedule are manufactured from animals known to be free of bovine spongiform encephalopathy. The risk of transmitting variant Creutzfeld Jakob disease from vaccines containing bovine-derived material is theoretical, estimated to be 1 in 40 billion or less.
    • Substances, such as formaldehyde, antibiotics, egg proteins or yeast proteins, may be needed for the vaccine manufacturing process.
      • Formaldehyde may be used to kill or weaken the virus or bacterium used to make a vaccine and is removed during the manufacturing process. Any trace amounts that may remain in the vaccine are safe. Formaldehyde is produced naturally in the body and helps with metabolism. There is approximately ten times the amount of formaldehyde in an infant’s body at any time than there is in a vaccine.
      • Antibiotics are used in some vaccines to prevent bacterial contamination during the manufacturing process. The types of antibiotics that are most likely to cause immediate hypersensitivity reactions (such as penicillin) are not contained in vaccines.
      • Egg proteins may be used for the growth of viruses used in some vaccines. Most of the egg protein is removed in the manufacturing process but very small amounts may remain in the final product. Refer to Anaphylactic Hypersensitivity to Egg and Egg-Related Antigens in Part 2 for additional information.
      • Yeast protein is used in the manufacture of some vaccines. Hypersensitivity to yeast is very rare and a personal history of yeast allergy is not generally reliable.
      • Vaccines do not contain cells from aborted fetuses or other human cells.
      • Human cell lines are used in the early stages of production of some vaccines; however, all cells are removed during purification of the vaccine.
      • Refer to Contents of Immunizing Agents in Part 1 for additional information.

Selected references

  • American Academy of Pediatrics. Questions and Answers about Vaccine Ingredients 2008. Accessed July 2012 at: http://www.aap.org/en-us/advocacy-and-policy/Documents/Vaccineingredients.pdf
  • Canadian Coalition for Immunization Awareness and Promotion. Immunization: get the facts. 2011. Accessed July 2012 at: http://www.immunize.cpha.ca/en/publications-resources/questions.aspx
  • Canadian Coalition for Immunization Awareness and Promotion. Immunization information on the internet: can you trust what you read? 2009. Accessed July 2012 at: http://www.immunize.cpha.ca/en/publications-resources/questions.aspx
  • Canadian Coalition for Immunization Awareness and Promotion. Vaccines do NOT contain harmful additives. 2008. Accessed July 2012 at: http://immunize.ca/uploads/fact3_additives_e.pdf
  • Canadian Health Services Research Foundation. Mythbusters – Myth: the risks of immunizing children often outweigh the benefits. 2006. Accessed July 2012 at: http://www.chsrf.ca/publicationsandresources/Mythbusters/ArticleView/06-12-01/e2a0f673-1439-48ea-b1c8-6a2c57f0c31f.aspx
  • Centers for Disease Control and Prevention. If You Choose Not to Vaccinate Your Child, Understanding the Risks and Responsibilities. 2009. Accessed July 2012 at: http://www.cdc.gov/vaccines/spec-grps/hcp/downloads/not-vacc-risks-bw-office.pdf
  • Centers for Disease Control and Prevention. Talking with Parents about Vaccines for Infants. 2010. Accessed July 2012 at: http://www.cdc.gov/vaccines/spec-grps/hcp/conv-materials.htm
  • Centers for Disease Control and Prevention. Understanding Thimerosal, Mercury, and Vaccine Safety. 2011. Accessed July 2012 at: http://www.cdc.gov/vaccines/spec-grps/hcp/downloads/vacsafe-thimerosal-bw-office.pdf
  • Department of Health and Human Services. Summary Workshop on Vaccine Communication, October 5-6, 2000 Arlington, Virginia. Accessed July 2012 at: http://www.dhhs.gov/nvpo/pubs/vcwsummary.pdf
  • Diekema DS. Improving Childhood Vaccination Rates. N Engl J Med 2012;366(5):391-93.
  • EKOS Research Associates Inc. Survey of Parents on Key Issues Related to Immunization. Final report submitted to the Public Health Agency of Canada on September 2011. Accessed May 2013 at: http://resources.cpha.ca/immunize.ca/data/1792e.pdf
  • Freed GL, Clark SJ, Butchart AT et al. Parental vaccine safety concerns in 2009. Pediatrics 2010;125:654-9.
  • Gold R. Your child's best shot: a parent's guide to vaccination. 2nd edition. Canadian Pediatric Society; 2002.
  • Health Canada. It’s your health: misconceptions about vaccine safety. 2009. Accessed July 2012 at: http://www.hc-sc.gc.ca/hl-vs/iyh-vsv/med/misconception-eng.php
  • Immunization Action Coalition. Talking about vaccines. Responding to concerns about vaccines. Accessed July 2012 at: http://www.immunize.org/concerns/
  • Institute of Medicine. 2013. The Childhood Immunization Schedule and Safety: Stakeholder Concerns, Scientific Evidence, and Future Studies. Committee on the Assessment of Studies of Health Outcomes Related to the Recommended Childhood Immunization Schedule; board on Population Health and Public Health Practice. Washington, DC: The National Academies Press.
  • Kata, A. A postmodern Pandora's box: anti-vaccination misinformation on the Internet. Vaccine 2009;28:1709-16.
  • Larson HJ, Cooper LZ, Eskola J et al. Addressing the vaccine confidence gap. Lancet, 2011;378:526-35.
  • Law, B. Are vaccines safe? Presented at the 14th Annual Child Health Research Symposium. March 12, 2008.
  • Leask J. Target the fence-sitters. Nature. 2011;473:443-5.
  • National Network for Immunization Information. Evaluating Information on the Web. Accessed July 2012 at: http://www.immunizationinfo.org/parents/evaluatingWeb.cfm
  • MacDonald NE, Finlay JC, Canadian Paediatric Society, Infectious Diseases and Immunization Committee. Working with vaccine-hesitant parents. Paediatr Child Health 2013;18:265-70. Offit PA, Jew RK. Addressing Parents’ Concerns: Do Vaccines Contain Harmful Preservatives, Adjuvants, Additives or Residuals? Pediatrics 2003;112:1394-1401.
  • Price CS, Thompson WW, Goodson B et al. Prenatal and Infant Exposure to Thimerosal from Vaccines and Immunoglobulins and Risk of Austism. Pediatrics 2010;126:565-64.
  • Spier RE. Perception of risk of vaccine adverse events: a historical perspective. Vaccine 2001;20:S78-84.
  • Tenrreiro KN. Time-efficient strategies to ensure vaccine risk/benefit communication. J Pediatr Nurs 2005;20:469-76.
  • Vaccine Education Centre at the Children’s Hospital of Philadelphia. Aluminum in Vaccines: What you should know. 2009. Accessed July 2012 at: http://www.chop.edu/export/download/pdfs/articles/vaccine-education-center/aluminum.pdf
  • Wilson K, Barakat M, Mills E et al. Addressing the Emergency of Pediatric Vaccination Concerns: Recommendations from a Canadian Policy Analysis. Can J Public Health 2006;97(2):139-41.
  • World Health Organization. Six common misconceptions about immunization. 2009. Accessed July 2012 at: http://www.who.int/immunization_safety/aefi/immunization_misconceptions/en/
  • World Health Organization. Vaccine Safety Net. 2012. Accessed July 2012 at: http://www.who.int/immunization_safety/safety_quality/vaccine_safety_websites/en/

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