last authored: October 2009, David LaPierre



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.


Specific Vaccines





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:

  • Nova Scotia, Canada
  • CDC

Nova Scotia, Canada



  • DaPTP-IPV-HiB (Pentacel) - 2,4,6, 18 months
  • pneumo. conj. - 2,4,6, 18 months
  • men c conj - 12 months
  • varicella - 12-15 months
  • MMR - 12 months, 4-6 years
  • flu - 6-23 months
  • DaPTP - 4-6 years
  • hepatitis B: 3 doses


  • Td: every 10 years





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 vaccines

Live vaccines in use include oral polio (primarily in developing countries), varicella, MMR, yellow fever, oral typhoid, and BCG against TB; used in confined populations during outbreaks.


Killed Vaccines

Isolated protein vaccines (subunit)

DNA (Vector) vaccines

Polysaccharide vaccines

Passive vaccines

Passive vaccines protect for approx. one month.

The effect of injecting immunoglobulin was first discovered in the late 1800s. Since then, Passive immunization has become standard practice in many cases.



Preparation of Immunoglobulin

Passive immunizations are prepared from the pooled plasma of thousands of donors, representing a sample of anitbodies that respond to a broad variety of pathogens. A gram of intravenous immunoglobulin (IVIG) may contain 1018 molecules of IG - mostly IgG and may represent up to 107 different antibody specificities.

Patients often receive 200-400 mg per kg, meaning a 70 kg man would receive 14-28 g every 3-4 weeks.

IVIG is treated exhaustively with solvents and detergents to reduce the risk of infectivity and to reduce aggregates that might trigger massive activation of the complement pathway and subsequent anaphylaxis.

Effects of IVIG

One of the most important uses of administered antibody is the recruitment of the complement pathway to destroy pathogens. Opsonization will target pathogens for phagocytosis, and toxins will be neutralized. Antibody-dependent cell-mediated cytotoxicity (ADCC) by NK cells also occurs.

Uses of IVIG

IgG is given to immunocompromized patients both IM and IV.

IgG given to healthy people

RSV IgG given to premature babies

given if risk of tetanus without recent booster

rabies if bitten





Vaccine Safety

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.

unlikely links:



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:



Vaccine Education

Canadian Pediatric society has a website for parents: Caring For Kids


Resources and References