Abstract

Introduction

Influenza virus infection frequently causes complications, the most common of which is pneumonia (primary or secondary), often leading to hospitalization and death. Influenza also exacerbates chronic diseases (chronic obstructive pulmonary disease, or COPD, cardiopathies, and other diseases with systemic repercussions) ¹1. Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza, ano 2014. Informe técnico. http://sprs.com.br/sprs2013/bancoimg/140402011250Informe_Campanha_Influenza_25_03_2014.pdf (acessado em 30/Out/2017).
http://sprs.com.br/sprs2013/bancoimg/140... . Influenza virus is one of the most prevalent respiratory viruses implicated in complications of COPD ²2. Zwaans WAR, Mallia P, van Winden MEC, Rohde GGU. The relevance of respiratory viral infections in the exacerbations of chronic obstructive pulmonary disease: a systematic review. J Clin Virol 2014; 61:181-8..

Vaccination is one of the most effective ways of preventing influenza and its complications ³3. Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep 2013; 62(RR-07):1-43.. In Brazil, annual vaccination campaigns have been held since 1999 and have contributed to the prevention of seasonal influenza in the population, with positive results in reducing complications, hospitalizations, expenditures on medication, and avoidable death ¹1. Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza, ano 2014. Informe técnico. http://sprs.com.br/sprs2013/bancoimg/140402011250Informe_Campanha_Influenza_25_03_2014.pdf (acessado em 30/Out/2017).
http://sprs.com.br/sprs2013/bancoimg/140... ^,44. Coordenação Geral do Programa Nacional de Imunizações, Departamento de Vigilância Epidemiológica, Secretaria de Vigilância em Saúde, Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza: informe técnico. 19ª Ed. Brasília: Ministério da Saúde; 2017.. In unvaccinated adults, the majority of complications and deaths occur in individuals with underlying diseases, while deaths from seasonal influenza in the unvaccinated population are reported mainly in the elderly ⁴4. Coordenação Geral do Programa Nacional de Imunizações, Departamento de Vigilância Epidemiológica, Secretaria de Vigilância em Saúde, Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza: informe técnico. 19ª Ed. Brasília: Ministério da Saúde; 2017..

The Centers for Disease Control and Prevention (CDC) ³3. Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep 2013; 62(RR-07):1-43. and the Brazilian Ministry of Health ¹1. Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza, ano 2014. Informe técnico. http://sprs.com.br/sprs2013/bancoimg/140402011250Informe_Campanha_Influenza_25_03_2014.pdf (acessado em 30/Out/2017).
http://sprs.com.br/sprs2013/bancoimg/140... recommend annual influenza vaccination in individuals with increased risk of complications of the disease, and for those living with or caring for these persons. Priority groups with formal recommendation of vaccination include the elderly (≥ 60 years) and individuals with chronic noncommunicable diseases (NCDs). In individuals with NCDs, the recommendation features those with chronic respiratory diseases (asthma, COPD, bronchiectasis, and pulmonary arterial hypertension, among others) ¹1. Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza, ano 2014. Informe técnico. http://sprs.com.br/sprs2013/bancoimg/140402011250Informe_Campanha_Influenza_25_03_2014.pdf (acessado em 30/Out/2017).
http://sprs.com.br/sprs2013/bancoimg/140... ^,33. Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep 2013; 62(RR-07):1-43.^,44. Coordenação Geral do Programa Nacional de Imunizações, Departamento de Vigilância Epidemiológica, Secretaria de Vigilância em Saúde, Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza: informe técnico. 19ª Ed. Brasília: Ministério da Saúde; 2017..

The benefits of vaccination in the elderly and individuals with chronic diseases have been reported in recent decades ³3. Centers for Disease Control and Prevention. Prevention and control of seasonal influenza with vaccines. MMWR Recomm Rep 2013; 62(RR-07):1-43., and many studies demonstrate the vaccine’s importance for preventing serious forms of influenza and pneumonia and reducing deaths in high-risk groups ⁵5. Francisco PMSB, Donalisio MR, Lattorre MRDO. Impacto da vacinação contra influenza na mortalidade por doenças respiratórias em idosos. Rev Saúde Pública 2005; 39:75-81.^,66. Francisco PMSB, Donalisio MR, Lattorre MRDO. Internações por doenças respiratórias em idosos e a intervenção vacinal contra influenza no Estado de São Paulo. Rev Bras Epidemiol 2004; 7:220-7.^,77. Luna EJA, Gattás VL, Campos SRSLC. Efetividade da estratégia brasileira de vacinação contra influenza: uma revisão sistemática. Epidemiol Serv Saúde 2014; 23:559-76.^,88. Nichol KL, Nordin JD, Nelson DB, Mullooly JP, Hak E. Effectiveness of influenza vaccine in the community-dwelling elderly. N Engl J Med 2007; 357:1373-81.^,99. Wang CS, Wang ST, Lai CT, Lin LJ, Chou P. Impact of influenza vaccination on major cause-specific mortality. Vaccine 2007; 25:1196-203.^,1010. Bekkat-Berkani R, Wilkinson T, Buchy P, Dos Santos G, Stefanidis D, Devaster J, et al. Seasonal influenza vaccination in patients with COPD: a systematic literature review. BMC Pulm Med 2017; 17:79.. Still, despite national and international recommendations for vaccination of these groups, international studies point to low vaccination rates in patients with chronic respiratory diseases ¹⁰10. Bekkat-Berkani R, Wilkinson T, Buchy P, Dos Santos G, Stefanidis D, Devaster J, et al. Seasonal influenza vaccination in patients with COPD: a systematic literature review. BMC Pulm Med 2017; 17:79.^,1111. Vozoris NT, Lougheed MD. Influenza vaccination among Canadians with chronic respiratory disease. Respir Med 2009; 103:50-8.^,1212. Mayo Montero EM, Hernández-Barrera V, Carrasco-Garrido P, Gil de Miguel A, Jiménez-García R. Influenza vaccination among persons with chronic respiratory diseases: coverage, related factors and time-trend, 1993-2001. Public Health 2007; 121:113-21.^,1313. Nitsch-Osuch A, Golebiak I, Wyszkowska D, Rosinska R, Kargul L, Szuba B, et al. Influenza vaccination coverage among Polish patients with chronic diseases. Adv Exp Med Biol 2017; 968:19-34..

Surveys on vaccination coverage in Brazilian adults and elderly with chronic respiratory disease (CRD) provide scarce data, and the prevalence of vaccination in this specific subgroup is insufficiently measured in general. The aim of this brief communication was thus to verify the prevalence of influenza vaccination in adults and elderly with CRD.

Methods

The study used public domain data for Brazilian adults (20-59 years; n = 23,329) and elderly (≥ 60 years; n = 9,019) from the Brazilian National Survey on Access, Utilization, and Promotion of Rational Use of Medicines (PNAUM), conducted from September 2013 to February 2014, available at http://www.ufrgs.br/pnaum/documentos/micro-dados.

The survey sample in the PNAUM included individuals living in urban households in Brazil. Calculation of the sample considered eight demographic domains (sex and age brackets) replicated for each of the five major geographic regions (40 sampling domains). The survey estimated 960 interviews per domain, and the selection was performed with three-stage probabilistic sampling: municipality (primary unit), census tract, and household. In the households, selection of individuals to participate in the survey was based on the expected proportion of each age group and sex to establish the final sample. The complex design guaranteed national representativeness of Brazil’s five major geographic regions, stratified by sex and age group. Details on the PNAUM methods were described by Mengue et al. ¹⁴14. Mengue SS, Bertoldi AD, Boing AC, Tavares NUL, da Silva Dal Pizzol T, Oliveira MA, et al. Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos (PNAUM): métodos do inquérito domiciliar. Rev Saúde Pública 2016; 50 Suppl 2:4s..

As for target variables selected for the study, the section with individual information collected sociodemographic characteristics, and the section on chronic diseases gathered information on influenza vaccination among individuals that reported CRDs.

The prevalence rates for influenza vaccination were estimated with respective 95% confidence intervals (95%CI). Associations were verified with the Rao-Scott chi-square test with significance set at 5%. All the analyses were performed with Stata 14.0 (StataCorp LP, College Station, USA), considering the study’s complex sampling design.

This study was performed with secondary data from the PNAUM survey and approved by the National Commission for Research Ethics (CONEP; case review 398.131, September 16, 2013).

Results

The mean age of the population ≥ 20 years was 44.0 years (95%CI: 43.4-44.6), and prevalence of CRD was 3% (95%CI: 2.7-3.3). Of the latter, 42.1% (95%CI: 37.2-47.1) reported influenza vaccination.

Some 50% of the sample resided in Southeast Brazil, the majority women, married, with ≤ 8 years of schooling, and without private health plans. In adults with CRD, there was a statistically significant difference in vaccination prevalence rates according to marital status (p < 0.05). In the elderly, there was a difference between the South and Northeast of Brazil (p < 0.05) (Table 1). Overall vaccination prevalence rates were 35.7% and 56.7% in adults and elderly, respectively (data not shown in table).

Table 2 shows the population’s distribution according to one or more CRDs (asthma, bronchitis, emphysema, or other respiratory disease) and vaccination rate. Chronic bronchitis was the most frequently reported disease (43.5%), and considering each specific disease, the proportion of vaccinated adults was low, ranging from 25% (other respiratory diseases) to 42% (chronic bronchitis), without a statistically significant difference (p = 0.330). The elderly also showed no significant difference in the vaccination rate (p = 0.225). The percentage of vaccinated elderly was higher than that in adults, among those reporting asthma, and in those reporting other respiratory diseases.

Discussion

In our study, influenza vaccination prevalence rates were low in adults and elderly with CRDs. According to the Brazilian Ministry of Health, in 2013, 7.3 million doses were administered in the “comorbidities” group, the majority of which in individuals with chronic respiratory disease (some 3.7 million) ¹1. Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza, ano 2014. Informe técnico. http://sprs.com.br/sprs2013/bancoimg/140402011250Informe_Campanha_Influenza_25_03_2014.pdf (acessado em 30/Out/2017).
http://sprs.com.br/sprs2013/bancoimg/140... . In 2016, this figure increased to 9.4 million doses (48% in the CRD subgroup) ⁴4. Coordenação Geral do Programa Nacional de Imunizações, Departamento de Vigilância Epidemiológica, Secretaria de Vigilância em Saúde, Ministério da Saúde. Campanha Nacional de Vacinação Contra a Influenza: informe técnico. 19ª Ed. Brasília: Ministério da Saúde; 2017..

No information is available on prevalence of influenza vaccination in specific groups of comorbidities in Brazil. However, international studies report low vaccination rates in persons with chronic respiratory diseases ¹⁰10. Bekkat-Berkani R, Wilkinson T, Buchy P, Dos Santos G, Stefanidis D, Devaster J, et al. Seasonal influenza vaccination in patients with COPD: a systematic literature review. BMC Pulm Med 2017; 17:79.^,1111. Vozoris NT, Lougheed MD. Influenza vaccination among Canadians with chronic respiratory disease. Respir Med 2009; 103:50-8.^,1212. Mayo Montero EM, Hernández-Barrera V, Carrasco-Garrido P, Gil de Miguel A, Jiménez-García R. Influenza vaccination among persons with chronic respiratory diseases: coverage, related factors and time-trend, 1993-2001. Public Health 2007; 121:113-21.^,1313. Nitsch-Osuch A, Golebiak I, Wyszkowska D, Rosinska R, Kargul L, Szuba B, et al. Influenza vaccination coverage among Polish patients with chronic diseases. Adv Exp Med Biol 2017; 968:19-34.. In Canada, prevalence of influenza vaccination was low in individuals with asthma (36.3%) and COPD (47.9%), and the main reason for non-vaccination was that the vaccine was considered unnecessary ¹¹11. Vozoris NT, Lougheed MD. Influenza vaccination among Canadians with chronic respiratory disease. Respir Med 2009; 103:50-8.. In Poland, besides low vaccination of patients with respiratory diseases (58%), the main barrier was lack of recommendation by healthcare professionals ¹³13. Nitsch-Osuch A, Golebiak I, Wyszkowska D, Rosinska R, Kargul L, Szuba B, et al. Influenza vaccination coverage among Polish patients with chronic diseases. Adv Exp Med Biol 2017; 968:19-34..

Various factors can contribute to the low prevalence of vaccination in individuals with chronic respiratory diseases. According to Vozoris & Lougheed ¹¹11. Vozoris NT, Lougheed MD. Influenza vaccination among Canadians with chronic respiratory disease. Respir Med 2009; 103:50-8., younger age groups, smokers, and individuals without access to family physicians are less likely to vaccinate. In Spain, older age, worse self-rated health, presence of comorbidities, and marital status (married) correlated with vaccination ¹²12. Mayo Montero EM, Hernández-Barrera V, Carrasco-Garrido P, Gil de Miguel A, Jiménez-García R. Influenza vaccination among persons with chronic respiratory diseases: coverage, related factors and time-trend, 1993-2001. Public Health 2007; 121:113-21..

The observed differences between the South and Northeast of Brazil may be explained partly by influenza prevalence, access to health services, vaccination coverage, and recommendation by physicians and other healthcare professionals, among other factors. Older individuals with chronic diseases may be more inclined to vaccinate due to the vaccine’s blanket recommendation for the elderly ¹²12. Mayo Montero EM, Hernández-Barrera V, Carrasco-Garrido P, Gil de Miguel A, Jiménez-García R. Influenza vaccination among persons with chronic respiratory diseases: coverage, related factors and time-trend, 1993-2001. Public Health 2007; 121:113-21.. Studies on reasons for low uptake by individuals with CRDs are still scarce in Brazil, as are studies on the relationship between different variables and vaccination.

We thus need to understand the reasons for the low coverage rates in this specific subgroup in order to develop appropriate strategies. Awareness-raising on influenza and the importance of vaccination, as well as recommendation of the vaccine by healthcare professionals, especially for individuals with chronic respiratory diseases, are strategies that can help increase vaccination coverage.

The study’s potential limitations should consider those reported by Mengue et al. ¹⁴14. Mengue SS, Bertoldi AD, Boing AC, Tavares NUL, da Silva Dal Pizzol T, Oliveira MA, et al. Pesquisa Nacional sobre Acesso, Utilização e Promoção do Uso Racional de Medicamentos (PNAUM): métodos do inquérito domiciliar. Rev Saúde Pública 2016; 50 Suppl 2:4s. that are inherent to household surveys such as addressing multiple topics. In this study in particular, the use of self-reported measures limited to cases of persons with CRD diagnosed by a physician may have been influenced by unequal access to healthcare and diagnostic services.

Conclusion

Considering the specific diseases analyzed here and that both individuals with CRDs and the elderly (≥ 60 years) are priority groups for annual influenza immunization, the findings point to low prevalence of vaccination and the need for strategic measures to improve adherence in this population subgroup.

References

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