HUMAN VACCINES & IMMUNOTHERAPEUTICS 2017, VOL. 13, NO. 1, 103–110 http://dx.doi.org/10.1080/21645515.2016.1228501
RESEARCH PAPER
Correlates of influenza vaccine uptake among community-dwelling older adults in Brazil Fabıola Bof de Andradea, Ana Paula Sayuri Satob, Roudom Ferreira Mourac, and Jose Leopoldo Ferreira Antunesb a Center for Studies in Public Health and Aging, Rene Rachou Research Institute, Oswaldo Cruz Foundation, Belo Horizonte, Brazil; bDepartment of Epidemiology, School of Public Health, University of S~ao Paulo, S~ao Paulo, Brazil; cCenter for Epidemiological Surveillance “Professor Alexandre Vranjac” of the S~ao Paulo State, S~ao Paulo, Brazil
ABSTRACT
ARTICLE HISTORY
This study aimed at assessing the factors associated with vaccine uptake in a representative sample of community-dwelling Brazilian older adults, specifically focusing on differences in socioeconomic factors among the country regions. We conducted a cross-sectional, population-based study, using a probabilistic household sample in 2013. Individuals aged 60 years or more answered a structured questionnaire informing on vaccination status and sociodemographic and behavioral covariates. Associations between variables were evaluated using prevalence ratios estimated by Poisson regression models. The overall vaccination coverage (72.6%) in older adults ranked lower than the goal of 80% stipulated by the Brazilian health authority; vaccine uptake differed significantly among the country regions. The prevalence of vaccination was lower in black individuals in Brazil than that in their white counterparts. The prevalence of vaccine uptake was significantly associated with covariates on current life style, use of health care, and socioeconomic determinants. Compared with individuals with 0–3 years of education, more schooled individuals had higher prevalence of vaccine uptake in the North, Northeast, and South regions of the country. This study showed that there is room for increasing vaccination coverage among the elderly in Brazil. The knowledge previously obtained on factors significantly associated with vaccine uptake has not prevented them to continue influencing this outcome. The socioeconomic inequality in vaccination in some Brazilian regions reinforces the need of targeting the intervention toward the most vulnerable groups.
Received 9 June 2016 Revised 1 August 2016 Accepted 20 August 2016
Introduction Seasonal influenza is a public health problem with significant socioeconomic implications.1 It is a respiratory infectious disease that affects 5–10% of the world’s adult population,1,2 causing 250,000–500,000 deaths in annual epidemics.2 Severe illness, complications, and hospitalizations are more frequent in groups including children aged less than 5 years, people with chronic diseases, and older individuals.1,3,4 In particular, older adults are considered to be at a higher risk for influenza-associated excess of mortality.5,6 Influenza vaccination is still the most effective way to prevent the disease and reduce the mortality rate among elderly individuals, albeit its efficacy in this age group is modest.1 Antunes et al.7 observed a reduction of 26% in the overall mortality due to influenza and pneumonia after the introduction of annual mass vaccination. Daufenbach et al. (2014)8 reported a decrease in the influenza-related hospitalization rate (0.75/ 1,000 elderly/year) among Brazilian elderly population between 1992 and 2006. In addition to reducing the risk of hospitalization and death, influenza vaccination may benefit older adults by preventing secondary complications (e.g., severe respiratory infections and cardiopulmonary disease).9,10 Although factors related to vaccine uptake have been widely investigated,4,11-13 continuous research is needed to evaluate CONTACT Fabıola Bof de Andrade, PhD © 2017 Taylor & Francis
fabiola.andrade@cpqrr.fiocruz.br
KEYWORDS
aging; coverage; epidemiology; inequalities; Influenza vaccination; uptake
whether the knowledge previously acquired has impacted on subsequent vaccination campaigns or the factors that have been identified as constraints to vaccination still continue influencing this outcome. The Advisory Group of the World Health Organization for Influenza Vaccines stated that the policymaking process demands studies assessing how attitudes are shaped and identifying the factors that are related to the decision to vaccinate.14 These studies became even more necessary with the emergence of the H1N1 (2009) pandemic, a more lethal virus, which reinforces vaccination as an essential public health intervention. Influenza vaccination has been implemented in Brazil since 1999 through nationwide campaigns that are usually conducted in April/May, immediately before the cold season. The Brazilian National Immunization Program provides free-of-charge influenza vaccination to the following groups: children aged 6 months to 5 years, pregnant women, old adults (aged 60 years or more), health professionals, indigenous population, and people with chronic diseases and other diseases that compromise immunity. Vaccine delivery is primarily conducted at primary health care units. The health system produces the vaccine and distributes it to each state, municipality, and public health service. In 2013, nearly 43 million doses of influenza vaccine were delivered at an estimated cost of almost 150 million Av. Augusto de Lima, 1715 - Barro Preto - Belo Horizonte/M.G - Brazil. 30.190-002.
104
F. B. DE ANDRADE ET AL.
US dollars; an additional financial transfer of more than 11 million dollars was demanded for the organization of the annual vaccination campaign.15 Vaccine uptake varies widely between and within regions, independent of the country’s level of economic development.11 In Brazil, previous studies have reported evidence on vaccination coverage in specific sites16-18 or in the biggest city of the country.12,19 However, no previous study has reported information regarding either the national level or its macroregions. This study aimed at assessing the factors associated with vaccine uptake in a representative sample of community-dwelling Brazilian older adults and evaluating the differences in the uptake related to socioeconomic factors among the country regions.
Results In this study of a representative sample of Brazilian older individuals, the overall prevalence of influenza vaccine uptake was 72.6% (95% CI: 71.1–74.1). Vaccination coverage was significantly different (p < 0.001) among the country regions, the Northeast region being the one with the lowest uptake (66.6%). The other regions showed vaccination uptake of more than 70% [North (71.2%); Southeast (73.6%), South (78.7%), and Midwest (75.4%)] (Fig. 1). The most frequent reason for not taking the vaccine in Brazil was the fear of vaccine side effects (25.8%), followed by the report that they rarely get the flu (24.9%) and that they do not believe that the vaccine protects against influenza (12.7%; Table 1). Table 2 depicts the distribution of population and shows the unadjusted assessment of covariates for vaccination in the whole sample. According to the results, vaccine uptake was significantly associated with 2 demographic variables (race and current marital relationship). A lower proportion of vaccination was observed among black individuals (66.9%) and among single, widowed, or divorced people (70.6%). Vaccine uptake was significantly associated with use of health services and life style factors (Table 2). According to the multiple regression model, the prevalence of influenza vaccine uptake was higher among older individuals and those currently married [PR D 1.05 (1.01–1.10)]. Black
elders had 9% lower prevalence of vaccine uptake when compared to whites. As regards current life style, the prevalence of vaccination was significantly higher among those who reported practicing physical activities [PR D 1.11 (1.06–1.16)] and about 17% lower among elders with unhealthy life style (i.e., binge drinking and smoking). The number of chronic diseases was the only general health variable related to vaccination. Older individuals with more than one chronic disease had more chance of being vaccinated. Being registered in the family health program, having had a recent health care visit, and having a health insurance plan significantly increased the prevalence of vaccine uptake, respectively, in 27%, 6%, and 8% of the individuals (Table 3). Table 4 shows the adjusted association of vaccine uptake and socioeconomic status according to the 5 Brazilian regions. Except in the Southeast and Midwest regions, the prevalence of vaccination was higher among more schooled individuals. In the North, the prevalence of vaccine uptake among individuals with 4–11 years of education was nearly 20% higher than that in individuals with 0–3 years of education. In the Northeast and South, this association was observed in individuals with 12 or more years of education, with an increase of 15% and 12%, respectively.
Discussion This study showed that vaccine uptake in Brazil ranked lower than the goal of 80% stipulated by the Brazilian Ministry of Health,20 although it was close to the 75% coverage suggested by the World Health Organization.21 Prevalence significantly differed between the country’s regions, and uptake was associated with race, lifestyle, and health services in Brazil. Schooling significantly increased the prevalence of vaccine uptake in the North, Northeast, and South regions. To the best of our knowledge, this was the first study to produce information regarding the factors related to vaccine uptake at the national level and its macroregions. The continuous monitoring of information on vaccine coverage and associated factors is relevant for the evaluation and planning of the vaccination program, primarily in Brazil, which encompasses a very large territory, with intense socioeconomic differences across its macroregions, and is committed in achieving a high population coverage.
Table 1. Reasons for not taking influenza vaccine. Country region
Reasons Afraid of vaccine side effect Rarely gets the flu Do not believe the vaccine protects against flu Afraid of shot Didn’t know it was necessary to take the vaccine Medical contraindication Vaccine was not available in the health care center Didn’t know where to take the vaccine Transport issues Health care center was far away No one to accompany to the health service Financial difficulties Other
Brazil
North
Northeast
Southeast
South
Midwest
% 25.8 24.9 12.7 7.1 5.2 3.4 2.8 1.4 1.4 1.1 0.6 0.1 13.6
% 29.2 15.8 10.1 8.9 7.4 2.6 1.6 3.9 0.9 4.6 2.2 0.0 12.7
% 25.5 19.2 12.7 9.1 4.4 2.9 3.5 1.7 1.7 1.6 1.0 0.1 16.6
% 26.2 31.5 13.1 4.6 6.5 3.0 2.4 0.9 1.1 0.2 0.0 0.1 10.3
% 27.2 17.6 13.5 12.1 2.1 6.3 2.3 0.3 1.6 1.3 0.0 0.2 15.3
% 18.4 26.6 9.8 4.4 3.0 4.3 3.9 3.3 1.2 1.6 2.7 0.0 20.8
HUMAN VACCINES & IMMUNOTHERAPEUTICS
Table 2. Descriptive statistics and Unadjusted PR according to total sample and country regions. Brazil, 2013 (ND11,175).
Table 3. Multiple variables analysis: Poisson regression model for influenza vaccination among the elderly (nD 11,175). Brazil, 2013.
Influenza vaccine uptake Variables Gender Male Female Age (years) 60 – 69 70 – 79 80 or more Race / skin color White Black Brown Yellow Indigenous Marital relationship No Yes Education (years) 0–3 4–8 8–11 12 or more Binge drinking No Yes Smoking No Yes Physical activity No Yes Number of chronic diseases 0 diseases 1 diseases 2C diseases Depression No Yes Disability No Yes Recent health care No Yes Health insurance No Yes Register in the Family Health Program No Yes Don’t know
%
Yes (%)
No (%)
43.6 56.4
71.9 73.1
28.1 26.9
Variables p-value
Gender Male Female Age (years) 60 – 69 70 – 79 80 or more Race / skin color White Black Brown Yellow Indigenous Marital relationship No Yes
0.456 0.149 56.4 30.0 13.6
71.6 74.8 72.1
28.4 25.2 27.9 0.032
53.6 9.2 35.6 1.3 0.3
74.1 66.9 71.4 83.9 71.4
25.9 33.1 28.6 16.1 28.6 0.021
42.6 57.4
70.6 74.1
29.4 25.9
Education (years) 0–3 4–7 8–11 12 or more
0.197 44.9 25.1 19.8 10.2
70.9 73.5 74.6 74.1
29.1 26.5 25.4 25.9
95.8 4.2
73.2 59.9
26.8 40.1
87.3 12.7
74.3 61.0
25.7 39.0
86.1 13.9
71.4 79.9
28.6 20.1
33.6 34.8 31.6
65.1 74.7 78.3
34.9 25.3 21.7
90.5 9.5
72.2 76.0
27.8 24.0
RESEARCH PAPER
Correlates of influenza vaccine uptake among community-dwelling older adults in Brazil Fabıola Bof de Andradea, Ana Paula Sayuri Satob, Roudom Ferreira Mourac, and Jose Leopoldo Ferreira Antunesb a Center for Studies in Public Health and Aging, Rene Rachou Research Institute, Oswaldo Cruz Foundation, Belo Horizonte, Brazil; bDepartment of Epidemiology, School of Public Health, University of S~ao Paulo, S~ao Paulo, Brazil; cCenter for Epidemiological Surveillance “Professor Alexandre Vranjac” of the S~ao Paulo State, S~ao Paulo, Brazil
ABSTRACT
ARTICLE HISTORY
This study aimed at assessing the factors associated with vaccine uptake in a representative sample of community-dwelling Brazilian older adults, specifically focusing on differences in socioeconomic factors among the country regions. We conducted a cross-sectional, population-based study, using a probabilistic household sample in 2013. Individuals aged 60 years or more answered a structured questionnaire informing on vaccination status and sociodemographic and behavioral covariates. Associations between variables were evaluated using prevalence ratios estimated by Poisson regression models. The overall vaccination coverage (72.6%) in older adults ranked lower than the goal of 80% stipulated by the Brazilian health authority; vaccine uptake differed significantly among the country regions. The prevalence of vaccination was lower in black individuals in Brazil than that in their white counterparts. The prevalence of vaccine uptake was significantly associated with covariates on current life style, use of health care, and socioeconomic determinants. Compared with individuals with 0–3 years of education, more schooled individuals had higher prevalence of vaccine uptake in the North, Northeast, and South regions of the country. This study showed that there is room for increasing vaccination coverage among the elderly in Brazil. The knowledge previously obtained on factors significantly associated with vaccine uptake has not prevented them to continue influencing this outcome. The socioeconomic inequality in vaccination in some Brazilian regions reinforces the need of targeting the intervention toward the most vulnerable groups.
Received 9 June 2016 Revised 1 August 2016 Accepted 20 August 2016
Introduction Seasonal influenza is a public health problem with significant socioeconomic implications.1 It is a respiratory infectious disease that affects 5–10% of the world’s adult population,1,2 causing 250,000–500,000 deaths in annual epidemics.2 Severe illness, complications, and hospitalizations are more frequent in groups including children aged less than 5 years, people with chronic diseases, and older individuals.1,3,4 In particular, older adults are considered to be at a higher risk for influenza-associated excess of mortality.5,6 Influenza vaccination is still the most effective way to prevent the disease and reduce the mortality rate among elderly individuals, albeit its efficacy in this age group is modest.1 Antunes et al.7 observed a reduction of 26% in the overall mortality due to influenza and pneumonia after the introduction of annual mass vaccination. Daufenbach et al. (2014)8 reported a decrease in the influenza-related hospitalization rate (0.75/ 1,000 elderly/year) among Brazilian elderly population between 1992 and 2006. In addition to reducing the risk of hospitalization and death, influenza vaccination may benefit older adults by preventing secondary complications (e.g., severe respiratory infections and cardiopulmonary disease).9,10 Although factors related to vaccine uptake have been widely investigated,4,11-13 continuous research is needed to evaluate CONTACT Fabıola Bof de Andrade, PhD © 2017 Taylor & Francis
fabiola.andrade@cpqrr.fiocruz.br
KEYWORDS
aging; coverage; epidemiology; inequalities; Influenza vaccination; uptake
whether the knowledge previously acquired has impacted on subsequent vaccination campaigns or the factors that have been identified as constraints to vaccination still continue influencing this outcome. The Advisory Group of the World Health Organization for Influenza Vaccines stated that the policymaking process demands studies assessing how attitudes are shaped and identifying the factors that are related to the decision to vaccinate.14 These studies became even more necessary with the emergence of the H1N1 (2009) pandemic, a more lethal virus, which reinforces vaccination as an essential public health intervention. Influenza vaccination has been implemented in Brazil since 1999 through nationwide campaigns that are usually conducted in April/May, immediately before the cold season. The Brazilian National Immunization Program provides free-of-charge influenza vaccination to the following groups: children aged 6 months to 5 years, pregnant women, old adults (aged 60 years or more), health professionals, indigenous population, and people with chronic diseases and other diseases that compromise immunity. Vaccine delivery is primarily conducted at primary health care units. The health system produces the vaccine and distributes it to each state, municipality, and public health service. In 2013, nearly 43 million doses of influenza vaccine were delivered at an estimated cost of almost 150 million Av. Augusto de Lima, 1715 - Barro Preto - Belo Horizonte/M.G - Brazil. 30.190-002.
104
F. B. DE ANDRADE ET AL.
US dollars; an additional financial transfer of more than 11 million dollars was demanded for the organization of the annual vaccination campaign.15 Vaccine uptake varies widely between and within regions, independent of the country’s level of economic development.11 In Brazil, previous studies have reported evidence on vaccination coverage in specific sites16-18 or in the biggest city of the country.12,19 However, no previous study has reported information regarding either the national level or its macroregions. This study aimed at assessing the factors associated with vaccine uptake in a representative sample of community-dwelling Brazilian older adults and evaluating the differences in the uptake related to socioeconomic factors among the country regions.
Results In this study of a representative sample of Brazilian older individuals, the overall prevalence of influenza vaccine uptake was 72.6% (95% CI: 71.1–74.1). Vaccination coverage was significantly different (p < 0.001) among the country regions, the Northeast region being the one with the lowest uptake (66.6%). The other regions showed vaccination uptake of more than 70% [North (71.2%); Southeast (73.6%), South (78.7%), and Midwest (75.4%)] (Fig. 1). The most frequent reason for not taking the vaccine in Brazil was the fear of vaccine side effects (25.8%), followed by the report that they rarely get the flu (24.9%) and that they do not believe that the vaccine protects against influenza (12.7%; Table 1). Table 2 depicts the distribution of population and shows the unadjusted assessment of covariates for vaccination in the whole sample. According to the results, vaccine uptake was significantly associated with 2 demographic variables (race and current marital relationship). A lower proportion of vaccination was observed among black individuals (66.9%) and among single, widowed, or divorced people (70.6%). Vaccine uptake was significantly associated with use of health services and life style factors (Table 2). According to the multiple regression model, the prevalence of influenza vaccine uptake was higher among older individuals and those currently married [PR D 1.05 (1.01–1.10)]. Black
elders had 9% lower prevalence of vaccine uptake when compared to whites. As regards current life style, the prevalence of vaccination was significantly higher among those who reported practicing physical activities [PR D 1.11 (1.06–1.16)] and about 17% lower among elders with unhealthy life style (i.e., binge drinking and smoking). The number of chronic diseases was the only general health variable related to vaccination. Older individuals with more than one chronic disease had more chance of being vaccinated. Being registered in the family health program, having had a recent health care visit, and having a health insurance plan significantly increased the prevalence of vaccine uptake, respectively, in 27%, 6%, and 8% of the individuals (Table 3). Table 4 shows the adjusted association of vaccine uptake and socioeconomic status according to the 5 Brazilian regions. Except in the Southeast and Midwest regions, the prevalence of vaccination was higher among more schooled individuals. In the North, the prevalence of vaccine uptake among individuals with 4–11 years of education was nearly 20% higher than that in individuals with 0–3 years of education. In the Northeast and South, this association was observed in individuals with 12 or more years of education, with an increase of 15% and 12%, respectively.
Discussion This study showed that vaccine uptake in Brazil ranked lower than the goal of 80% stipulated by the Brazilian Ministry of Health,20 although it was close to the 75% coverage suggested by the World Health Organization.21 Prevalence significantly differed between the country’s regions, and uptake was associated with race, lifestyle, and health services in Brazil. Schooling significantly increased the prevalence of vaccine uptake in the North, Northeast, and South regions. To the best of our knowledge, this was the first study to produce information regarding the factors related to vaccine uptake at the national level and its macroregions. The continuous monitoring of information on vaccine coverage and associated factors is relevant for the evaluation and planning of the vaccination program, primarily in Brazil, which encompasses a very large territory, with intense socioeconomic differences across its macroregions, and is committed in achieving a high population coverage.
Table 1. Reasons for not taking influenza vaccine. Country region
Reasons Afraid of vaccine side effect Rarely gets the flu Do not believe the vaccine protects against flu Afraid of shot Didn’t know it was necessary to take the vaccine Medical contraindication Vaccine was not available in the health care center Didn’t know where to take the vaccine Transport issues Health care center was far away No one to accompany to the health service Financial difficulties Other
Brazil
North
Northeast
Southeast
South
Midwest
% 25.8 24.9 12.7 7.1 5.2 3.4 2.8 1.4 1.4 1.1 0.6 0.1 13.6
% 29.2 15.8 10.1 8.9 7.4 2.6 1.6 3.9 0.9 4.6 2.2 0.0 12.7
% 25.5 19.2 12.7 9.1 4.4 2.9 3.5 1.7 1.7 1.6 1.0 0.1 16.6
% 26.2 31.5 13.1 4.6 6.5 3.0 2.4 0.9 1.1 0.2 0.0 0.1 10.3
% 27.2 17.6 13.5 12.1 2.1 6.3 2.3 0.3 1.6 1.3 0.0 0.2 15.3
% 18.4 26.6 9.8 4.4 3.0 4.3 3.9 3.3 1.2 1.6 2.7 0.0 20.8
HUMAN VACCINES & IMMUNOTHERAPEUTICS
Table 2. Descriptive statistics and Unadjusted PR according to total sample and country regions. Brazil, 2013 (ND11,175).
Table 3. Multiple variables analysis: Poisson regression model for influenza vaccination among the elderly (nD 11,175). Brazil, 2013.
Influenza vaccine uptake Variables Gender Male Female Age (years) 60 – 69 70 – 79 80 or more Race / skin color White Black Brown Yellow Indigenous Marital relationship No Yes Education (years) 0–3 4–8 8–11 12 or more Binge drinking No Yes Smoking No Yes Physical activity No Yes Number of chronic diseases 0 diseases 1 diseases 2C diseases Depression No Yes Disability No Yes Recent health care No Yes Health insurance No Yes Register in the Family Health Program No Yes Don’t know
%
Yes (%)
No (%)
43.6 56.4
71.9 73.1
28.1 26.9
Variables p-value
Gender Male Female Age (years) 60 – 69 70 – 79 80 or more Race / skin color White Black Brown Yellow Indigenous Marital relationship No Yes
0.456 0.149 56.4 30.0 13.6
71.6 74.8 72.1
28.4 25.2 27.9 0.032
53.6 9.2 35.6 1.3 0.3
74.1 66.9 71.4 83.9 71.4
25.9 33.1 28.6 16.1 28.6 0.021
42.6 57.4
70.6 74.1
29.4 25.9
Education (years) 0–3 4–7 8–11 12 or more
0.197 44.9 25.1 19.8 10.2
70.9 73.5 74.6 74.1
29.1 26.5 25.4 25.9
95.8 4.2
73.2 59.9
26.8 40.1
87.3 12.7
74.3 61.0
25.7 39.0
86.1 13.9
71.4 79.9
28.6 20.1
33.6 34.8 31.6
65.1 74.7 78.3
34.9 25.3 21.7
90.5 9.5
72.2 76.0
27.8 24.0
