Immunization

last authored: April 2012, David LaPierre
last reviewed:

 

 

Introduction

Vaccination, or immunization, is the administration of antigen to develop an immune response, including cellular activation and antibody production, in order to prevent subsequent infection. The term vaccine, derived from latine for cow, was coined by Pasteur in honour of Edward Jenner's work with cowpox.

 

Infants below one year of age - Anterolateral thigh; after this, use the deltoid.

 

Common reactions include low-grade fever lasting up to 24 hours and redness at the site. Parents should be reassured and told to offer acetaminophen; if symptoms do not improve, they should bring the child in.

 

 

 

Specific Vaccines

Viruses

Bacteria

 

 

 

Vaccine Schedules

Premature infants should receive vaccinations based on their chronological age, regardless of birthweight, not calculated age. THe exception is hepatitis B, which should not be given under 2 kg.

 

Various locales have differing vaccination policies. Some of these include:

  • Public Health Agency of Canada
  • CDC

Public Health Agency of Canada

 

Childhood

  • DaTP-IPV-HiB - Diptheria, Pertussis, Tetanus, Polio, Hemophilus Influenza B
    • 2,4,6, 18 months
  • pneumococcus conjugate - 2,4,6, 18 months
  • meningitis c conjugate - 12 months
  • varicella - 12-15 months
  • MMR measles, mumps, rubella -12 months, 18 months, or 4-6 years
  • influenza - 6-23 months
  • DaPTP - 4-6 years
  • hepatitis B: 3 doses

Adolescence

  • human papillomavirus (HPV) - ages 9-13, three doses

Adulthood

  • Tdap: every 10 years

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Definitions

antigen: substance to which specific antibodies form

hapten: protein conjugates to vaccine antigen to enhance
immune response

adjuvant: substance increasing immunogenicity (ie alum)

preservative: substance to reduce contamination
(ie thimerosol, phenol)

stabilizer: substance to maintain integrity during temperature
change (ie gelatin, sucrose)

manufacturing residual: inactivating agent (ie formaldehyde)
or cellular material (ie egg protein)

Types of Vaccines

 

 

 

 

 

 

 

 

 

 

 

 

  • live vaccine
  • killed vaccine
  • isolated protein vaccine
  • polysaccharide vaccine
  • DNA vaccine
  • passive vaccine

Live vaccines

  • Most effective vaccine, made from live pathogens that have been somehow attenuated to make them non-pathogenic but can still replicate
  • Effectiveness due to the fact that organism persists for longer periods, and multiple epitopes present
  • Can, on rare occasions, revert to become pathogenic again
  • absolutely contraindicated with pregnancy

Live vaccines in use include:

  • oral polio (primarily in developing countries)
  • varicella
  • measles, mumps, rubella (MMR)
  • yellow fever
  • oral typhoid
  • BCG against TB (used in confined populations during outbreaks)

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Vaccine Safety and Contraindications

As with almost all health interventions, vaccines carry benefits and risks. As they are usually given to healthy people to prevent disease, they are held to a higher standard of safety.

 

Immediate Reactions

The most common adverse event is local injection site pain, lasting <48 hours. The MMR is especially painful.

Systemic reactions such as fever are less common, and must be reported by physicians to ensure safety for others.

Causality of other events is more difficult to prove.

 

Many people are concerned about the safety of vaccines.

unlikely links:

Thimerosol has been very controversial in regards to causing autism or autism spectrum disorder; however, and increasing body of knowledge suggests there is no link (Price et al, 2010).

 

Minor illnesses, such as the common cold, with or without fever, are NOT contraindications for immunization. However, moderate or severe illness precludes vaccination.

 

Other contraindications include:

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Difficulty with Vaccine Design

Many pathogens resist killing following with vaccines.

Many parasites have different stages during their life cycle, each with various antigens. Effective vaccines would need to address various stages.

 

 

Resources and References