Canadian Immunization Guide
Seventh Edition - 2006

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Part 3
Recommended Immunization

Immunization of Adults

Prevention of infection by immunization is a lifelong process. There are a number of vaccines that all adults (≥ 18 years) require. There are also other vaccines that need to be tailored to meet individual variations in risk resulting from occupation, foreign travel, underlying illness, lifestyle and age.

Immunization does not stop at childhood!

Childhood immunization programs have significantly reduced vaccine-preventable diseases among children, but Canada's population has an increasing number of adults who remain vulnerable to these diseases. For example, a random digit dialing telephone survey conducted in 2002 among Canadians aged ≥18 found that only 54% of respondents had adequate coverage for tetanus, and this rate was lowest in those aged ≥ 60. Furthermore, although overall rates of vaccination are rising as compared with previous years, only two-thirds of Canadians aged ≥ 65 surveyed in 2000/2001 reported receiving Influenza vaccination, and only 47% of those aged ≥ 20 with at least one chronic complication placing them at increased risk of Influenza had been vaccinated.

Reasons for adults not being immunized

The following are common reasons for incomplete immunization in the adult years:

• Lack of recommendation from their physician
• Misrepresentation/misunderstanding of the risks of vaccine and benefits of disease prevention in adults
• Lack of understanding of vaccine safety and efficacy
• Missed opportunities for receiving the vaccine at health care encounters in physicians' offices, hospitals and nursing homes
• Lack of publicly funded vaccine and reimbursement to health care providers
• Lack of coordinated immunization programs for all adults
• Lack of regulatory or legal requirements
• Fear of injections
• Lack of availability of up-to-date records and recording systems

Health care provider as health advocate

Health professionals have the responsibility to prevent vaccine-preventable diseases in those under their care. Failure to maintain adult immunization results in significant individual risk, increased mortality and community risk for preventable diseases. Society not only expects health practitioners to promote newly approved interventions that maintain health and prevent disease but also to ensure that the population under their care has continuing and updated protection through appropriate immunization. Health care providers are recognized as leaders in their community, and their behaviours and attitudes can be a positive force for health promotion. They must present factual information concerning immunization and vaccines and also be able to review the benefits and risks of these interventions. This must be done in a manner that promotes the well-being of the individual, the family and the community.

Strategies to improve vaccine uptake in adults

Four categories of effective intervention that increase vaccine uptake have been described by Shefer et al. Interventions that increase the demand include community education, patient reminders, incentives and patient-held records. Educational programs for health care providers are also effective. However, the two interventions that had the greatest success in enhancing access to immunization were programs that decrease costs and those that include legal or regulatory interventions. Stone et al. in their meta-analysis of controlled clinical trials concluded that organizational changes, such as the introduction of specific clinics and the participation of non-physician staff to execute the specific prevention strategies, were the most effective ways to enhance uptake. Johnston and Conly have conducted an excellent review of these issues.

All adults should be counselled concerning their personal immunization status. Health care providers should regularly review the patients under their care to ensure not only that their immunization status is up to date but also that they have been made aware of new vaccines. Practitioners should regularly audit their patients' immunization records during clinical encounters that coincide with a mid-decade birthday (i.e., 15, 25, 35, 45, 55 years etc.).

There are a number of patient encounters/situations that provide opportunities for general vaccine counselling in adults:

• "New" patient/client encounter as part of the "history"
• Patient hospitalization, especially when the diagnosis is a chronic disease
• Patients requesting specific vaccination(s), e.g., pneumococcal vaccine or Influenza vaccine
• Patients with evidence of "risk taking" behaviour, such as illicit drug use or a sexually transmitted disease
• Individuals requesting advice concerning international travel
• Periodic health examinations
• Visits for chronic disease management
• Management protocols on admission to nursing and long-term care institutions
• Pregnancy and the immediate post-partum period
• Assessment of new immigrants to Canada
• New employee assessments in health care and health care-related facilities
• Parents attending their children's vaccination visits

Immunizations recommended for adults - routine

All adults should be immunized against diphtheria, tetanus, pertussis, measles, mumps, rubella and varicella. The schedule for adults who have no record or an unclear history of prior immunization as well as for booster dosing of those who have completed a prior primary series is shown in Table 5.

All Canadian adults require maintenance of immunity to tetanus and diphtheria, preferably with combined (Td) toxoid and a single dose of acellular pertussis vaccine. The first priority is to ensure that children receive the recommended series of doses, including the school leaving dose at 14 to 16 years of age, and that adults have completed primary immunization with Td. Currently, only a single dose of acellular pertussis (given as Tdap) is recommended in adulthood because the duration of protection from Tdap has yet to be determined. For adults not previously immunized against pertussis only one dose of Tdap is required as it is assumed that most adults will have some degree of immunity due to prior pertussis infection.

Combined measles, mumps, rubella vaccine (MMR) is preferred for vaccination of individuals not previously immunized against one or more of these viruses. Adults born before 1970 may be considered immune to measles. Adults born in 1970 or later who do not have documentation of adequate measles immunization or who are known to be seronegative should receive MMR vaccine. One additional dose of vaccine should be offered only to adults born in 1970 or later who are at greatest risk of exposure and who have not already received two doses or demonstrated immunity to measles. These people include travellers to a measles-endemic area, health care workers, students in post-secondary educational settings and military recruits. MMR is recommended for all adults without a history of mumps or mumps immunization. MMR vaccine should also be given to all adults without a history of rubella vaccination. Female adolescents and women of childbearing age should be vaccinated before pregnancy or post-partum, unless they have documented evidence of detectable antibody or prior vaccination. In addition, it is also important that health care workers of either sex be actively immunized against rubella because they may, through frequent face-to-face contact, expose pregnant women to rubella.

A history of chickenpox infection is adequate evidence of varicella immunity. Serologic testing should be performed in adults without a history of disease, as the majority of such adults will be immune and do not require the varicella vaccine. It is particularly important to promote varicella immunization with immigrants and refugees from tropical countries, women of childbearing age, those who are at occupational risk of exposure, including health care and child care workers, household contacts of immunocompromised persons, those with cystic fibrosis, and those susceptible adults exposed to a case of varicella. There are no data at present to guide recommendations for varicella booster dosing in adults following the primary vaccination series.

Table 5. Adult Immunization Schedule - Routinely for All

Immunizations for adults - specific risk groups

There are several specific groups of adults for whom certain vaccines are recommended because of the presence of risk factors for disease, and these are summarized in Table 6. In many cases, individual factors, and in particular the presence of underlying co-morbid illnesses, define groups that specifically benefit from certain vaccines. However, there are two commonly encountered groups of healthy adults who require assessment for a series of vaccines: health care workers and international travelers. In both of these groups, the priority should be to ensure that routinely recommended immunizations are completed and booster doses provided as indicated.

Health care workers, including hospital employees, other staff who work or study in hospitals (e.g., students in health care disciplines and contract workers), other health care personnel (e.g., those working in clinical laboratories, nursing homes and home care agencies) and child care workers, are at risk of exposure to communicable diseases because of their contact with patients or material from individuals with infections, both diagnosed and undiagnosed.

Hepatitis B is the most important vaccine-preventable infectious occupational disease for health care workers. The risk of being infected is a consequence of the prevalence of virus carriers in the population receiving care, the frequency of exposure to blood and other body fluids and the contagiousness of hepatitis B virus. Hepatitis B vaccine is recommended for health care workers and others who may be exposed to blood or blood products, or who may be at increased risk of sharps injury, bites or penetrating injuries (for example, clients and staff of institutions for the developmentally challenged). Annual Influenza immunization is recommended for all health care personnel who have contact with individuals in high-risk groups. Such personnel include physicians, nurses and others in both hospital and outpatient settings; employees of chronic care facilities; and providers of home care, visiting nurses and volunteers. Influenza immunization of health care workers has been shown to reduce the mortality and morbidity of patients under their care in long-term settings and to reduce worker illness and absenteeism during the Influenza season. Other vaccines may be indicated for certain workers at particularly high risk of exposure, such as laboratory workers in specialized reference or research facilities. These include but are not limited to typhoid, meningococcal, BCG, rabies, and smallpox vaccines. An individualized risk-benefit assessment is required.

International travelers represent another defined group requiring specific vaccine consideration. Ensuring that traveling adults have completed a primary series of routine vaccinations is the first priority (Table 6). This is particularly important because many vaccine-preventable diseases remain endemic in developing countries. Although completion of primary polio vaccination is adequate in most adults, a one-time polio booster (> 10 years since primary vaccination) is recommended for adults who have not had a previous booster and are traveling to polio-endemic countries. It is also important that travelers who are in specific risk groups for routine vaccines (such as pneumococcal and Influenza vaccines in those ≥ 65) receive the ones indicated. With travel-specific vaccines, an individualized approach is required that considers a patient's health status, risk of exposure and complications from vaccine-preventable illness, as well as location and duration of travel. Most commonly these include consideration for immunization against yellow fever, Japanese encephalitis, typhoid, cholera, meningococcal disease, rabies, and hepatitis A and B, as listed in Table 6.

Adults ≥65 years of age and those with conditions that increase their chances of complications should receive one dose of pneumococcal vaccine and yearly Influenza vaccine. Opportunities to increase Influenza vaccination should be taken; it is estimated that less than one-half of high-risk Canadians receive Influenza vaccine annually. Increasing the rate of Influenza vaccination of health care workers and household contacts of individuals with increased risk of Influenza complications will not only affect the vaccinated individuals but may also result in substantial secondary benefit to others.

Hepatitis A vaccination is recommended for those at increased risk of exposure (see Hepatitis A Vaccine chapter). Universal immunization against hepatitis B is recommended in childhood in Canada, and opportunities should be provided for adults to receive hepatitis B vaccine. Adults who are at increased risk of exposure to hepatitis B by virtue of their occupation, lifestyle or environment should receive the vaccine at the earliest possible clinical encounter. Patients may be vaccinated simultaneously for hepatitis A and B using a combined vaccine. Because of their increased risk for complications, all non-immune patients with chronic liver disease should be vaccinated against hepatitis A and B.

Cholera vaccine should be considered for high-risk travelers to cholera-endemic countries (please refer to the Immunization of Travellers chapter).

Meningococcal C conjugate vaccines are recommended for immunization of young adults to prevent the increased risk of serogroup C meningococcal disease in these age groups. Meningococcal vaccine is recommended for certain groups with increased risk of meningococcal disease (please refer to the Meningococcal Vaccine chapter). Such individuals include those with functional or anatomic asplenia; persons with complement, properdin or factor D deficiency; military recruits; research, industrial and clinical laboratory personnel who are routinely exposed to Neisseria meningitidis cultures; and travelers to high-risk areas. In cases in which risk is restricted to group C disease, monovalent serogroup C meningococcal conjugate vaccine may be preferred. Meningococcal vaccine is also used for outbreak management.

Although oral poliovirus vaccine is no longer used in Canada, individuals who have received a primary vaccination series with this vaccine are considered immune. Immunization of adults against poliovirus should be considered for those at increased risk (see Poliomyelitis Vaccine chapter).

Rabies vaccine should be offered, before exposure, to those individuals at high risk as a result of occupational or travel exposure to rabid animals. These may include veterinarians, laboratory workers, animal control and wildlife workers, spelunkers, trappers and hunters, and travelers to endemic countries where there may be limited access to safe and effective post-exposure prophylaxis.

Typhoid vaccine is recommended for high-risk international travelers, including those with prolonged (> 4 weeks) exposure in an endemic region or those with shorter duration of stay in particularly high-risk situations (please refer to the Typhoid Vaccine chapter). Although routine vaccination of health care workers is not required, laboratory workers who frequently handle live cultures of Salmonella typhi should be vaccinated.

Naturally occurring smallpox has been eradicated worldwide, and as a result vaccination is highly restricted. Laboratory workers who handle vaccinia or other orthopoxviruses should be considered for vaccination.

Table 6. Adult Immunization Schedule - Specific Risk Situations

Selected references

Canadian Association for the Study of the Liver. Canadian Consensus Conference on the Management of Viral Hepatitis. Canadian Journal of Gastroenterology 2000;14(Suppl B):5B-20B.

Committee to Advise on Tropical Medicine and Travel (CATMAT). Statement on poliomyelitis vaccination for international travellers (evidence-based medicine recommendations). Canada Communicable Disease Report 1995;21(16):145-48.

Committee to Advise on Tropical Medicine and Travel (CATMAT); National Advisory Committee on Immunization (NACI). Statement on new oral cholera and travellers' diarrhea vaccination. Canada Communicable Disease Report 2005;31(ACS-7):1-11.

Coulibaly N, De Serres G. Coverage of anti-tetanus vaccinations in adults in Canada - year 2002. Canadian Journal of Public Health 2004;95(6):456-59.

Health Canada. Smallpox vaccination of laboratory workers. Canada Communicable Disease Report 2004;30(19):167-9.

Johansen H, Nguyen K, Mao L et al. Influenza vaccination. Health Reports 2004;15(2):33-43.

Johnston BL, Conly JM. Routine adult immunization in Canada: recommendations and performance. Canadian Journal of Infectious Diseases 2002;13(4):226-31.

Lau DT, Hewlett AT. Screening for hepatitis A and B antibodies in patients with chronic liver disease. American Journal of Medicine 2005;118(Suppl 10A):28S-33S.

National Advisory Committee on Immunization (NACI). Statement on recommended use of meningococcal vaccines. Canada Communicable Disease Report 2001;27(ACS-6):2-36.

National Advisory Committee on Immunization (NACI). Statement on smallpox vaccination. Canada Communicable Disease Report 2002;28(ACS-1):1-12.

National Advisory Committee on Immunization (NACI). Prevention of pertussis in adolescents and adults. Canada Communicable Disease Report 2003;29(ACS-5):1-9.

National Advisory Committee on Immunization (NACI). Update on varicella. Canada Communicable Disease Report 2004;30(ACS-1):1-26.

Shefer A, Briss P, Rodewald L et al. Improving immunization coverage rates: an evidence-based review of the literature. Epidemiologic Reviews 1999;21(1):96-142.

Spira AM. Preparing the traveller. Lancet 2003;361(9366):1368-81. Statement on travellers and rabies vaccine. Canadian Medical Association Journal 1995;152(8):1241-45.

Stone EG, Morton SC, Hulscher ME et al. Interventions that increase use of adult immunization and cancer screening services: a meta-analysis. Annals of Internal Medicine 2002;136(9):641-51.

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