Estimating Influenza Vaccine Effectiveness in Spain Using Sentinel Surveillance Data
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Research articles Estimating influenza vaccine effectiveness in Spain using sentinel surveillance data S Jiménez-Jorge ([email protected])1,2, S de Mateo1,2, C Delgado-Sanz1,2, F Pozo3, I Casas3, M García-Cenoz2,4, J Castilla2,4, C Rodriguez5, T Vega5, C Quiñones6, E Martínez6, J M Vanrell7, J Giménez7, D Castrillejo8, J M Altzíbar2,9, F Carril10, J M Ramos11, M C Serrano11, A Martínez2,12, N Torner2,12, E Pérez13, V Gallardo13, A Larrauri1,2, on behalf of the Spanish Influenza Sentinel Surveillance System14 1. National Centre of Epidemiology, Institute of Health Carlos III, Madrid, Spain 2. CIBER Epidemiología y Salud Pública (CIBERESP), Institute of Health Carlos III, Madrid, Spain 3. National Centre for Microbiology, National Influenza Reference Laboratory, WHO National Influenza Centre, Institute of Health Carlos III, Madrid, Spain 4. Instituto de Salud Pública de Navarra, Navarre, Spain 5. Dirección General de Salud Pública, Consejería de Sanidad de Castilla y León, Valladolid, Spain 6. Servicio de Epidemiología y Prevención Sanitaria, Dirección General de Salud Pública y Consumo de La Rioja, La Rioja, Spain 7. Servicio de Epidemiología, Dirección General de Salut Pública, Mallorca, Baleares, Spain 8. Servicio de Epidemiología. Dirección General de Sanidad y Consumo, Consejería de Bienestar Social y Sanidad, Ciudad Autónoma de Melilla, Melilla, Spain 9. Dirección de Salud Pública de Gipuzkoa, País Vasco, San Sebastián, Spain 10. Servicio de Salud Pública, Departamento de Salud, Gobierno del País Vasco, Álava, Spain 11. Dirección General de Salud Pública, Servicio Extremeño de Salud, Junta de Extremadura, Mérida, Spain 12. Servicio de Vigilancia Epidemiológica, Dirección General de Salud Pública, Departament de Salut, Generalitat Catalunya, Barcelona, Spain 13. Servicio de Epidemiología y Salud Laboral, Secretaría General de Salud Pública y Participación, Consejería de Salud de Andalucía, Sevilla, Spain 14. Institutions involved in the network are listed at the end of the article (vgripe.isciii.es/gripe/) Citation style for this article: Jiménez-Jorge S, de Mateo S, Delgado-Sanz C, Pozo F, Casas I, García-Cenoz M, Castilla J, Rodriguez C, Vega T, Quiñones C, Martínez E, Vanrell JM, Giménez J, Castrillejo D, Altzíbar JM, Carril F, Ramos JM, Serrano MC, Martínez A, Torner N, Pérez E, Gallardo V, Larrauri A, on behalf of the Spanish Influenza Sentinel Surveillance System. Estimating influenza vaccine effectiveness in Spain using sentinel surveillance data. Euro Surveill. 2015;20(28):pii=21187. Available online: http://www.eurosurveillance.org/ViewArticle.aspx?ArticleId=21187 Article submitted on 25 July 2014/ published on 16 July 2015 We aimed to estimate influenza vaccine effective- information would optimise the system to provide reli- ness (VE) against laboratory-confirmed influenza dur- able annual influenza VE estimates to guide influenza ing three influenza seasons (2010/11 to 2012/2013) vaccination policies. in Spain using surveillance data and to compare the results with data obtained by the cycEVA study, Introduction the Spanish component of the Influenza Monitoring Influenza causes considerable morbidity worldwide, Vaccine Effectiveness (I-MOVE) network. We used the even among those who are not in vulnerable high-risk test-negative case–control design, with data from the groups, and therefore represents a public health prob- Spanish Influenza Sentinel Surveillance System (SISS) lem with socio-economic implications [1]. Influenza vac- or from the cycEVA study. Cases were laboratory-con- cination has the potential to prevent annual morbidity firmed influenza patients with the predominant influ- and premature mortality. The influenza vaccine is refor- enza virus of each season, and controls were those mulated every year and consequently its effectiveness testing negative for any influenza virus. We calculated must be estimated annually [1]. In Europe, seasonal the overall and age-specific adjusted VE. Although and pandemic influenza vaccine effectiveness (VE) has the number of patients recorded in the SISS was three been monitored since the 2008/09 influenza season times higher than that in the cycEVA study, the quality through the Influenza Monitoring Vaccine Effectiveness of information for important variables, i.e. vaccination (I-MOVE) project [2], a publicly funded network sup- status and laboratory results, was high in both stud- ported by the European Centre for Disease Prevention ies. Overall, the SISS and cycEVA influenza VE esti- and Control (ECDC) and European Union (EU) Member mates were largely similar during the study period. For States in the framework of the European sentinel influ- elderly patients (> 59 years), the SISS estimates were enza systems. Since the inception of I-MOVE, Spain slightly lower than those of cycEVA, and estimates has participated through an observational case–con- for children (0–14 years) were higher using SISS in trol study to monitor influenza VE in Spain (cycEVA). two of the three seasons studied. Enhancing the SISS This study is conducted within the framework of well- by collecting the date of influenza vaccination and established sentinel influenza networks comprising the reducing the percentage of patients with incomplete Spanish Influenza Sentinel Surveillance System (SISS). www.eurosurveillance.org 29 Figure 1 Test-negative controls and laboratory-confirmed influenza cases by type/subtype of influenza virus and epidemiological week, Spanish Influenza Sentinel Surveillance System (A) and cycEVA study (B), 2010/11, 2011/12 and 2012/13 seasons, Spain A. Spanish Influenza Surveillance System B. cycEVA study I I L 400 800 400 800 L I 2010/11 2010/11 I p p a a t t i i e e n n s s t t t t 300 600 s 300 600 s n n / e e / i i t t 100 a a 100 p p I I L L Vaccination Vaccination , I I , 000 000 f f 200 400 200 400 o o campaign campaign r r e e popu popu b b m m u u N N 100 200 100 200 l l a a t t i i on on 0 0 0 0 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 Epidemiological weeks Epidemiological weeks I L I L 400 800 400 800 I I p 2011/12 p 2011/12 a a t i t e i e n n t s s s t t t 300 600 s 300 600 / n n / e e i i 100 t t 100 a a p p I I Vaccination Vaccination , L L 000 , I I 000 f 200 400 f 200 400 o campaign o campaign r r popu e e popu b b m m u u N N 100 200 100 200 l a l a t i t on i on 0 0 0 0 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 Epidemiological weeks Epidemiological weeks I I 250 800 250 800 L L 2012/13 2012/13 I I p p a a t t i i e e 200 200 n n s s t t t 600 t 600 s s n n / / e e i i t t 100 100 a a p 150 p 150 I I , L L , I I Vaccination Vaccination 000 000 f 400 f 400 o o campaign campaign r r e e 100 100 popu popu b b m m u u N N l 200 l 200 a a 50 50 t t i i on on 0 0 0 0 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 40 42 44 46 48 50 52 2 4 6 8 10 12 14 16 18 20 Epidemiological weeks Epidemiological weeks Test-negative controls Influenza A not subtyped-positive cases ILI incidence sentinel regions Influenza A(H3N2)-positive cases Influenza B-positive cases Influenza A(H1N1)pdm09-positive cases cycEVA study: the Spanish component of the Influenza Monitoring Vaccine Effectiveness (I-MOVE) network; ILI: influenza-like illness. Participating sentinel physicians follow a European level [9]. However, after the initial ECDC funding was protocol specifically designed for this study [3]. The exhausted (December 2012), the Spanish cycEVA study protocol includes systematic swabbing of recruited encountered serious difficulties in continuing to meas- patients and recording the date of influenza vaccina- ure influenza VE. Therefore, a major challenge in Spain tion and information on potential confounding factors and the rest of Europe is sustaining these VE studies. that have not been historically collected during influ- enza surveillance. Through five influenza seasons, the Influenza surveillance data have been used in Australia, cycEVA study has provided timely and reliable [4-8] the United Kingdom (UK) and Canada [10-12] to monitor influenza VE estimates and has been useful in guiding influenza VE using the test-negative control approach, public vaccination policy at the national and European an efficient method of estimating VE [13]. Because 30 www.eurosurveillance.org surveillance data are already available, this method is diseases, chronic pulmonary diseases, congenital or less costly than observational studies. acquired immunodeficiency, diabetes mellitus, chronic hepatic disease and chronic renal disease) and risk fac- The SISS was established in 1996 to provide timely epi- tors (i.e. pregnancy (in women aged 15–44 years) and demiological and virological information on influenza morbid obesity (defined as body mass index (BMI) ≥ 40 activity in Spain [14]. The SISS also participates in the kg/m2)). European Influenza Surveillance Network (EISN). After more than 15 years, the SISS has been demonstrated to Vaccination status is collected as a dichotomous vari- be a robust system for monitoring seasonal influenza able (yes/no); this information is collected either by [15].