Vaccine uptake in Canadian adults: results from the 2014 adult National Immunization Coverage Survey
- National immunization coverage targets for adulthood vaccines were not met among the general Canadian population, those at high risk for severe complications associated with vaccine-preventable diseases and healthcare personnel.
- While most individuals believed that they received all vaccines required for someone their age, less than 10% were up-to-date on their adult immunizations.
- More effort is required to increase adult immunization coverage in Canada, especially among high risk groups.
Immunization is a major accomplishment for public health, effectively preventing infectious disease and improving the health of Canadians. While most routine immunizations are provided during childhood, vaccinations are recommended in adulthood as well. Immunizations are important for adults for the following reasons:
- immunity against certain vaccine-preventable diseases wanes over time and requires boosting (e.g. tetanus)
- certain vaccine-preventable infections are more virulent in adults and can cause serious disability and death (e.g. varicella)
- adult immunization helps establish immunity against certain diseases that are more common in adulthood (e.g. herpes zoster, also known as shingles)
- adult immunization helps prevent infection and therefore protect vulnerable people who cannot be immunized, are not yet fully immunized or are unable to build strong immunity to vaccines. This includes young infants, vulnerable patients in hospitals or institutions, and those with immune-compromising conditions such as cancer or human immunodeficiency virus (HIV).
The aNICS was conducted in 2001, 2006, 2008, 2010, 2012 and 2014. This report details the survey results from the 2014 cycle.
The questionnaire was developed in consultation with immunization experts across Canada. NACI-recommended target groups were identified including: individuals aged 65 years and older, adults aged 18 to 64 years with chronic medical conditions, and healthcare personnel (defined as individuals working or volunteering in a healthcare setting). Respondents were surveyed on the acceptability of immunization and on whether they have enough information about the benefits of immunization. The survey also included demographic questions on age, gender, education, employment status, household income, and country of birth.
All respondents were asked if they had received the seasonal influenza vaccine in the past year; ever vaccinated against hepatitis B; ever received a dose of pertussis-containing vaccine in adulthood; and if they had received a tetanus vaccine in the last 10 years. In addition to the above items, individuals under 65 years of age were also asked if they had ever been vaccinated against varicella, and those 45 years-old and younger were asked about immunization against HPV. Pneumococcal vaccine uptake was asked in respondents 65 years of age or older and adults with chronic medical conditions.
In addition to RDD, individuals working in a healthcare setting were identified from the MD Select (published by Scott's Info Medical) for physicians and Dun & Bradstreet Canada national database for other healthcare occupations. Relevant healthcare organizations were selected from the Dun & Bradstreet database, and then contacted to identify eligible respondents.
National coverage estimates for each recommended adult vaccine were calculated as the number of positive responses (i.e. having received the vaccine) expressed as a percentage of the sum of positive and negative responses (excluding those who did not know or declined to respond). Estimates were weighted to represent the Canadian population in terms of age, gender and region size, using information from the 2011 Census Footnote 3. National data for healthcare professionals were weighted by age and region. Coverage estimates were stratified by target groups for certain vaccines.
The response rate for adults in the general population (i.e. recruited through RDD) was 11%, and 13% among the list-based sample for healthcare personnel. Overall, 3,290 adult respondents completed the interview by telephone, with 3,040 participants recruited through RDD and an additional 250 healthcare personnel from targeted databases. In total, 565 healthcare personnel participated in the survey (315 through RDD and 250 from list-based sampling).
In the general adult sample (n=3040), 52% were female and 19% were born outside Canada. The median age was 48 years (range 18 - 97 years) with 17% being 65 years of age and older. There were 715 Canadians aged 18 to 64 years of age with a chronic medical condition (31%). Most participants had some postsecondary education (34%) or had completed university (38%), and a quarter of the sample had an annual household income greater than $100,000 before taxes.
Among the sample of healthcare personnel (n=565), the median age was 46 years (range 19 - 94 years) and most were female (77%). The most common occupations included nurses (31%), physicians (12%), nursing assistants (10%) and administrators (10%). The majority of healthcare personnel (70%) reported having close contact (within one meter) with patients or residents.
The estimated immunization coverage for influenza, tetanus, pertussis and pneumococcal vaccines among adults and healthcare personnel are summarized in Table 1.
|Participants||n||Vaccine coverage (%) for at least one dose (95% confidence interval)|
|InfluenzaTable 1 - Footnote ‡||TetanusTable 1 - Footnote ¶||PertussisTable 1 - Footnote §||PneumococcalTable 1 - Footnote ǁ|
|Adults (≥ 18 years)||3040||40.3 (38.3, 42.3)||49.5 (47.4, 51.7)||9.3 (8.1, 10.5)||-|
18-64 years of age with a chronic medical condition Table 1 - Footnote *
|715||43.8 (39.6, 48.1)||51.4 (47.1, 55.8)||8.4 (6.0, 10.8)||17.3 (13.7, 20.8)|
≥ 65 years of age
|831||67.1 (63.4, 70.7)||38.0 (34.1, 41.9)||8.9 (6.5, 11.2)||36.5 (32.7, 40.3)|
|Healthcare personnelTable 1 - Footnote †||565||69.2 (64.6, 73.9)||68.3 (63.7, 72.8)||23.0 (18.7, 27.2)||-|
Close contact with patient or resident (within one meter)
|394||75.6 (70.8, 80.4)||70.1 (65.0, 75.2)||23.7 (18.6, 28.7)||-|
i) Seasonal influenza immunization
Less than half of the adults (40%) received a dose of the influenza vaccine for the 2013-2014 season. Coverage was the highest among healthcare personnel having close contact with patients or residents (Table 1). As compared with other NACI-recommended target groups, adults with a chronic medical condition had the lowest coverage.
ii) Pertussis and tetanus immunizations
For tetanus, NACI recommends that all adults receive a booster dose of tetanus toxoid-containing vaccine every 10 years Footnote 2. Approximately 50% of Canadian adults reported receiving a vaccine against tetanus in the past 10 years (Table 1). Among individuals who have been treated for a wound in the last decade (n=899), 80% (95% confidence intervals [CI] 76.9, 83.1) had a tetanus toxoid-containing vaccine.
iii) Pneumococcal polysaccharide immunization (Pneu-P-23)
iv) Hepatitis B immunization
Estimates on coverage for hepatitis B vaccine among high-risk groups are presented in Table 2. Healthcare personnel at risk for occupational exposure most frequently reported having received a hepatitis B vaccine as compared to the other target groups (Table 2).
|Participants||n||Coverage (%) for at least one dose of hepatitis B vaccine (95% confidence interval)Table 2 - Footnote *|
|Adults with chronic liver/kidney disease or a blood disorder||135||45.5 (35.4, 55.7)|
|Healthcare personnelTable 2 - Footnote ^||565||72.2 (67.9, 76.5)|
Personnel with occupational exposure to blood/bodily fluids, or at risk for needle-stick/surgical blade injury or human bite
|407||84.3 (80.3, 88.1)|
v) Varicella immunization
vi) Human papillomavirus immunization
Among females (n=86) and males (n=84) 18 to 26 years of age, 44.7% (95%CI 33.1, 56.3) and 7.6% (95%CI 1.3, 13.9) reported receiving at least one dose of the HPV vaccine, respectively. Females 27 to 45 years of age (n=436), 8.3% (95%CI 5.3, 11.3) were vaccinated with at least one dose of the HPV vaccine.
vii) Knowledge, attitudes, and beliefs towards immunization
Most adults (88%; 95%CI 86.7, 89.4) and healthcare personnel (92%, 95%CI 89.4, 95.0) believed that immunization is a recognized healthcare practice in their family. Additionally, 77% (95%CI 75.8, 79.4) of adults and 91% (95%CI 88.3, 93.5) of healthcare personnel reported that they knew enough about the benefits of immunization. While 80% (95%CI 78.5, 81.9) of individuals believed that they received all of the vaccines required for someone their age, only 6% (95%CI 5.3, 7.4) had the recommended number of pertussis and tetanus vaccine doses in adulthood.
While immunization coverage was higher among healthcare personnel as compared to the general adult population, many remained unvaccinated for publicly-funded vaccines such as influenza, pertussis and tetanus. In this target group, vaccination against hepatitis B was reported most frequently.
There are limitations to the 2014 aNICS study. The low response rate increases the risk of non-response bias (i.e. vaccine uptake may be different in those who did not participate) and limits the representativeness of the sample. Additionally, results are based solely on self-reported immunization history. The ability of the participant to recall specific vaccinations is influenced by their existing knowledge of vaccines and their understanding of the risks associated with the vaccine preventable-diseases. The self-reported results are likely to impact the accuracy and reliability of the estimates, resulting in under- or over-estimation of immunization coverage. As well, self-reported chronic medical conditions were not validated with medical records, which may have resulted in misclassification of individuals in high-risk groups. The aNICS results may not be directly comparable to coverage data reported by other countries because of differences in definitions of high-risk groups and measurement of vaccination coverage.
Immunization coverage estimates varied across target groups. There is room for improvement, as many Canadians are not up-to-date in their immunizations according to NACI-recommended schedules.
The aNICS constitutes an ongoing approach to measuring adult immunization coverage in Canada and monitoring progress towards national targets. The next aNICS cycle will take place in 2016. The Public Health Agency of Canada will continue to work to collaborate with provinces, territories and other stakeholders to improve immunization coverage assessment methodology. Public and professional education and outreach campaigns will also continue to promote the benefits and safety of immunization in Canada.
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