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Canadian Immunization Guide

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Part 1

Benefits of Immunization

Benefits of immunization

Immunization is one of the most important advances in public health and is estimated to have saved more lives in Canada over the past 50 years than any other health intervention. Before vaccines became available, many Canadian children died from diseases such as diphtheria, measles and polio that are now preventable by immunization. Immunization programs are responsible for the elimination, containment or control of infectious diseases that were once common in Canada; however, the viruses and bacteria that cause vaccine preventable diseases still exist globally, can be imported to Canada through travel, and can be transmitted to people who are not protected by immunization. If immunization programs were reduced or stopped, diseases that are now rarely seen in Canada because they are controlled through immunization would re-appear, resulting in epidemics of diseases causing sickness and death. This phenomenon has been seen in other countries; for example, large epidemics of diphtheria and measles have occurred in Europe in recent decades after immunization rates declined.

Immunization is important in all stages of life. Infants and young children are particularly susceptible to vaccine preventable diseases because their immune systems are not mature enough to fight infection; as a result, they require timely immunization. Older children and adults also require immunization to restore waning immunity and to build new immunity against diseases that are more common in adults.

Immunization directly protects individuals who receive vaccines. Through herd immunity, immunization against many diseases also prevents the spread of infection in the community and indirectly protects:

  • infants who are too young to be vaccinated,
  • people who cannot be vaccinated for medical reasons (e.g., certain immunosuppressed people who cannot receive live vaccines),
  • people who may not adequately respond to immunization (e.g.the elderly).

Impact of vaccines on vaccine preventable diseases

Table 1, Figures 1, 2, and 3 illustrate the impact of vaccines on infectious diseases in Canada. Refer to Part 4 chapters for additional information about the success of immunization programs against specific vaccine preventable diseases.


Table 1: incidence of select vaccine preventable diseases in Canada – pre-vaccine era compared with 2007-2011
Disease and impact Vaccine introduction & Disease reporting Pre-vaccine era 2007-2011Footnote 1
Pre-vaccine period 5-year average annual incidence per 100,000 Peak annual number of casesFootnote * 5-year average annual incidence per 100,000 Peak annual number of cases
Table 1 - Footnote *
Five years preceding vaccine introduction
Table 1 - Footnote 1
Provisional numbers for measles and rubella from the Canadian Measles and Rubella Surveillance System. All other data from the Canadian Notifiable Disease Surveillance System.
Table 1 - Footnote 2
Children less than 5 years of age
Table 1 - Footnote 3
Reported cases of newly diagnosed HBV infection per 100,000 population. Combines acute, chronic and unspecified HBV infections.
Table 1 - Footnote 4
Reported cases of newly diagnosed HBV infection in 1989.
Table 1 - Footnote 5
Reported cases of newly diagnosed HBV infection per 100,000 population. Combines acute, chronic and unspecified HBV infections.
Table 1 - Footnote 6
Reported cases of newly diagnosed HBV infection in 2008.
Table 1 - Footnote 7
In 2011, a large outbreak of measles occurred in Quebec; a total of 752 cases were reported in Canada. Excluding 2011, the peak number of cases was 102 (2007), and the average annual incidence for this time period (i.e. 2007 – 2010) was 0.21 cases per 100,000 population.
Table 1 - Footnote 8
Per 100,000 live births.
Diphtheria
Infection of the throat causes severe breathing difficulty which may result in asphyxia. Infection also results in the dissemination of diphtheria toxin, which damages the heart and central nervous system. In the pre-vaccine era case fatality was about 5% to 10%, with highest death rates occurring in the very young and the elderly.
  • Diphtheria toxoid introduced in 1926
  • Routine infant immunization since 1930
  • National notifiable diseases reporting began in 1924
1925-1929 84.2 9,010 0.006 4
Haemophilus influenzae type b (Hib) invasive disease (children less than 5 years of age)
Infection can cause meningitis, epiglottitis, bacteremia, cellulitis, pneumonia or septic arthritis in young children. Case fatality rate of meningitis is about 5%. Severe neurologic sequelae occur in 10% to 15% of survivors and deafness in 15% to 20%
  • Vaccines first introduced in 1986
  • Conjugate vaccine introduced in 1988
  • Routine infant immunization since 1988-89
  • National notifiable disease reporting of all invasive Hib disease began in 1986
1986-1990 30.1Footnote 2 671 0.49Footnote 2 18
Hepatitis B (HB)
Infection in approximately 10% of adults results in chronic infection leading to a chronic carrier state that may result in cirrhosis, liver cancer, and death.
  • Universal HB immunization for adolescents implemented in the early- to mid-1990s
  • National notifiable disease reporting of HB infection began in 1969
1989-1993 9.1Footnote 3 3,378Footnote 4 5.3Footnote 5 2,011Footnote 6
Measles
Bronchopneumonia and otitis media occur in about 1/10 cases and encephalitis occurs in 1/1,000 cases (fatal in 15% and neurologic sequelae in 25%). Case fatality rate is 1-2 per 1000. Subacute sclerosing panencephalitis is a rare but fatal complication.
  • Live vaccine authorized in 1963
  • Universal immunization program implemented in 1983
  • 2-dose measles-containing vaccine schedule introduced 1996/97
  • National notifiable diseases reporting began in 1924 (no reporting from 1959 to 1968)
1950-1954 372.7 61,370 0.60Footnote 7 752Footnote 7
Meningococcal serogroup C invasive disease
Invasive meningococcal disease most often results in meningitis or septicemia. Severe cases can result in delirium and coma and, if untreated, shock and death. Case fatality rate is 10%, and 10-20% of survivors have severe sequelae such as limb amputations and deafness.
  • Polysaccharide vaccines first introduced in Canada in 1981
  • Routine infant or toddler immunization programs using conjugate vaccine introduced across Canada between 2002 and 2006
  • National notifiable disease reporting began in 1924
1997-2001 0.30 186 0.06 30
Mumps
Acute parotitis develops in 40%, of which 25% are unilateral. Complications include orchitis (20% to 30% of post-pubertal males), oophoritis (5% of post-pubertal females), meningitis (<10% of cases), deafness (0.5 to 5/100,000 cases) and encephalitis (less than 1/50,000 cases). Occasionally mumps can cause permanent infertility or deafness.
  • Vaccine authorized in 1969
  • Universal immunization program implemented in 1983
  • National notifiable disease reporting began in 1924 (no reporting from 1960 to 1985)
1950-1954 251.2 43,671 1.84 1,110
Pertussis
Young infants may experience complications, such as vomiting after a coughing spell, weight loss, breathing problems, choking spells, pneumonia, convulsions, brain damage, and in rare cases, death. Older children and adults develop persistent cough lasting for up to 6 weeks.
  • Whole cell pertussis vaccine authorized in 1943
  • Acellular pertussis vaccine replaced whole cell in 1997-1998
  • Adolescent and adult acellular vaccine formulation authorized in 1999
  • National notifiable disease reporting began in 1924
1938-1942 156.0 19,878 3.88 1,961
Poliomyelitis
Paralysis occurs in less than 1% of infections but among those paralyzed, about 2 - 5% of children and 15-30% of adults die.
  • Inactivated polio vaccine (IPV) authorized in 1955
  • Oral polio vaccine authorized in 1962 and in use in Canada until 1996
  • IPV used primarily from 1996-present
1950-1954 17.5 5,384 0 0
Rubella and congenital rubella syndrome (CRS)
Although rubella is generally a mild disease, encephalitis occurs in 1/6,000 cases. However, rubella infection in pregnancy can cause congenital rubella syndrome (CRS). Infection in the first 10 weeks of pregnancy has an 85% risk of leading to CRS. CRS can result in miscarriage, stillbirth and fetal malformations (congenital heart disease, cataracts, deafness and mental retardation).
  • Rubella vaccine introduced 1969
  • Universal immunization program implemented in 1983
  • National notifiable disease reporting began in 1924
  • National notifiable diseases reporting of CRS began in 1979
Rubella: 1950-1954
CRS: 1979-1983
Rubella: 106.3
CRS: 3.08Footnote 8
Rubella: 37,917
CRS: 29
Rubella: 0.01
CRS: 0.11Footnote 8
Rubella:10
CRS: 1
Tetanus
Infection leads to general rigidity, and convulsive spasms, with death in about 10% of cases. Higher rates of death occur among infants.
  • Tetanus toxoid introduced in 1940
  • National notifiable diseases reporting began in 1957
1935-1939 0.13 25 0.01 6

Figure 1: Haemophilus influenzae type b disease – reported number of casesFootnote 1 and incidence rates, Canada, 1979-2010Footnote 2

Text Equivalent - Figure 1


Footnote 1
Case data obtained from the Canadian Notifiable Disease Surveillance System. Population data obtained from Statistics Canada July 1st annual estimates. Data for 2009 and 2010 are preliminary.
Footnote 2
Only Hib meningitis was reportable from 1979 to 1985. After this, all invasive disease caused by Hib became reportable
Footnote 3
PRP-D: Hib conjugate vaccine containing purified polyribosylribitol phosphate capsular polysaccharide of Hib covalently bound to diphtheria protein. The vaccine was licensed in 1986 and in 1988 introduced into the majority of provincial vaccination programs.

Figure 2: Diphtheria – reported number of cases and incidence rates, Canada, 1924-2008

Text Equivalent - Figure 2

Population data sources: Statistics Canada, Population by Sex and Age, 1921-1971, revised annual estimates of population, Canada and the provinces, (Catalogue 91-512) Statistics Canada, Population estimates 0-90+ July Canada - Provinces 1971-2008.xls


Figure 3: Rubella - reported number of cases and incidence rates, Canada, 1979 to 2010

Text Equivalent- Figure 3


Cost benefit of vaccines

Vaccine preventable diseases result in significant costs to individuals, the health care system, and society, including costs associated with visits to health care providers, hospitalizations, and premature deaths. Parents may lose time from work to care for sick children and sick children lose time at school. For example, the societal cost for each case of rotavirus requiring a visit to the emergency room is estimated to be $675.

The cost-benefit of vaccine is strongly influenced by the price of the vaccines used. Many vaccines, such as measles-mumps-rubella vaccine for children, provide both health benefits and savings in health care costs (refer to Table 2). This means that the cost of implementing the immunization program is less than the cost of treating the illness or injury that would occur if the program had not been not implemented. Because immunization with these vaccines improves health and results in cost savings, the decision to include these vaccines in publicly funded immunization programs is straightforward. In developing public health programs, international organizations such as the World Health Organization, United Nations Children’s Fund and the World Bank recommend that immunization be given high priority because of its high cost-effectiveness.

Table 2: Cost savings achieved through selected immunization programs
Immunization program Cost saving per $1 spent
Influenza for adults 65 years of age and older $45
Measles, mumps, rubella for children $16
Pneumococcal polysaccharide for adults 65 years of age and older $8
Diphtheria, pertussis, tetanus for children $6

Newer vaccines tend to be costlier and may not be cost-saving, so the decision to introduce them into publicly funded immunization programs is determined by society’s willingness to pay for their anticipated health benefits. In general, such programs compare very favourably to other public health interventions in terms of cost per life year saved (refer to Table 3). In Canada, evaluation of benefits and costs of new immunization programs is done by Provinces and Territories. Refer to Immunization in Canada for more information.


Table 3: Cost per life year saved for selected immunization programs and other public health interventions (adapted from references)
Public health intervention Cost per life year savedFootnote 1
Table 1 - Footnote 1
monetary resources required to save one year of "statistical" life
Vaccines
Hepatitis B screening in pregnancy and immunization of children of carriers $164
Human papillomavirus vaccine for 12 year old girls in a school-based immunization program $12,921
Varicella vaccine for children $16,000
Pneumococcal conjugate vaccine for children $125,000
Other interventions
Mandatory seat belt law $69
Chlorination of drinking water $3,100
Smoking cessation counseling $1,000 to $10,000
Annual screening for cervical cancer $40,000
Driver and passenger air bags/manual lap belts (vs. airbag for driver only and belts) $61,000
Smoke detectors in homes $210,000
Crossing control arm for school buses $410,000
Radiation emission standard for nuclear power plants $100,000,000

Selected references

  • Centers for Disease Control and Prevention. An ounce of prevention - what are the returns? Second edition, 1999. Accessed July 2012 at: www.cdc.gov/epo/prevent.htm
  • Centers for Disease Control and Prevention. Basics and Common Questions: How Vaccines Prevent Disease. Accessed July 2012 at: http://www.cdc.gov/vaccines/vac-gen/howvpd.htm#why
  • Centers for Disease Control and Prevention. Basics and Common Questions: What Would Happen If We Stopped Vaccinations? Accessed July 2012 at: http://www.cdc.gov/vaccines/vac-gen/howvpd.htm#why
  • Centers for Disease Control and Prevention. Basics and Common Questions: Why Immunize? Accessed July 2012 at: http://www.cdc.gov/vaccines/vac-gen/why.htm
  • Centers for Disease Control and Prevention. Guide to contraindications to vaccinations. Accessed July 2012 at: http://www.cdc.gov/vaccines/recs/vac-admin/contraindications.htm
  • Coyle D, Coyle K, Bettinger JA et al. Cost effectiveness of infant vaccination for rotavirus in Canada. Can J Infect Dis Med Microbiol 2012;23(2):71-77.
  • Ess SM, Szucs TD. Economic evaluation of immunization strategies. Clin Infect Dis 2002;35:294-7.
  • Schiefele, David W. The Impact of Vaccines in Canada: More Than a Century of Success. Accessed July 2012 at: http://www.onehealth.ca/r_alberta_nwt/video_conferences/R080312B-HOa.pdf
  • Tengs, TO, Adams ME, Pliskin JS et al. Five hundred live-saving interventions and their cost-effectiveness. Risk Anal 1995;15:369-90.
  • Tully S, Anonychuk A, Sanchez D et al. Time for change? An economic evaluation of integrated cervical screening and HPV immunization programs in Canada. Vaccine 2012;30:425-35.
  • World Health Organization, United Nations Children's Fund, World Bank. State of the World's Vaccines and Immunization. Geneva, Switzerland: World Health Organization; 2009;3rd edition. Accessed February 2013 at http://whqlibdoc.who.int/publications/2009/9789241563864_eng.pdf

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