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Eurosurveillance, Volume 21, Issue 22, 02 June 2016
Research article
Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season
J Castilla 1 2 , A Navascu?s 3 , M Fern?ndez-Alonso 4 , G Reina 4 , E Alb?niz 5 , F Pozo 6 , N ?lvarez 5 7 , I Mart?nez-Baz 1 2 , M Guevara 1 2 , M Garc?a-Cenoz 1 2 , F Irisarri 1 2 , I Casado 1 2 , C Ezpeleta 3 , Primary Health Care Sentinel Network and Network for Influenza Surveillance in Hospitals of Navarra 8
+ Author affiliations
1. Instituto de Salud P?blica de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
2. CIBER Epidemiolog?a y Salud P?blica (CIBERESP), Madrid, Spain
3. Complejo Hospitalario de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
4. Cl?nica Universidad de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
5. Servicio Navarro de Salud, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
6. Centro Nacional de Microbiologia (World Health Organization National Influenza Centre Madrid), Instituto de Salud Carlos III, Majadahonda, Spain
7. Red de Investigaci?n en Servicios de Salud en Enfermedades Cr?nicas (REDISSEC), Pamplona, Spain
8. The members of these networks are listed at the end of the article
Correspondence: Jes?s Castilla (jcastilc@navarra.es)
Citation style for this article: Castilla J, Navascu?s A, Fern?ndez-Alonso M, Reina G, Alb?niz E, Pozo F, ?lvarez N, Mart?nez-Baz I, Guevara M, Garc?a-Cenoz M, Irisarri F, Casado I, Ezpeleta C, Primary Health Care Sentinel Network and Network for Influenza Surveillance in Hospitals of Navarra. Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season. Euro Surveill. 2016;21(22):pii=30243. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.22.30243
Received:27 July 2015; Accepted:25 February 2016
We estimated whether previous episodes of influenza and trivalent influenza vaccination prevented laboratory-confirmed influenza in Navarre, Spain, in season 2013/14. Patients with medically-attended influenza-like illness (MA-ILI) in hospitals (n = 645) and primary healthcare (n = 525) were included. We compared 589 influenza cases and 581 negative controls. MA-ILI related to a specific virus subtype in the previous five seasons was defined as a laboratory-confirmed influenza infection with the same virus subtype or MA-ILI during weeks when more than 25% of swabs were positive for this subtype. Persons with previous MA-ILI had 30% (95% confidence interval (CI): −7 to 54) lower risk of MA-ILI, and those with previous MA-ILI related to A(H1N1)pdm09 or A(H3N2) virus, had a, respectively, 63% (95% CI: 16?84) and 65% (95% CI: 13?86) lower risk of new laboratory-confirmed influenza by the same subtype. Overall adjusted vaccine effectiveness in preventing laboratory-confirmed influenza was 31% (95% CI: 5?50): 45% (95% CI: 12?65) for A(H1N1)pdm09 and 20% (95% CI: −16 to 44) for A(H3N2). While a previous influenza episode induced high protection only against the same virus subtype, influenza vaccination provided low to moderate protection against all circulating subtypes. Influenza vaccine remains the main preventive option for high-risk populations.
full article
Research article
Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season
J Castilla 1 2 , A Navascu?s 3 , M Fern?ndez-Alonso 4 , G Reina 4 , E Alb?niz 5 , F Pozo 6 , N ?lvarez 5 7 , I Mart?nez-Baz 1 2 , M Guevara 1 2 , M Garc?a-Cenoz 1 2 , F Irisarri 1 2 , I Casado 1 2 , C Ezpeleta 3 , Primary Health Care Sentinel Network and Network for Influenza Surveillance in Hospitals of Navarra 8
+ Author affiliations
1. Instituto de Salud P?blica de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
2. CIBER Epidemiolog?a y Salud P?blica (CIBERESP), Madrid, Spain
3. Complejo Hospitalario de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
4. Cl?nica Universidad de Navarra, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
5. Servicio Navarro de Salud, IdiSNA - Navarra Institute for Health Research, Pamplona, Spain
6. Centro Nacional de Microbiologia (World Health Organization National Influenza Centre Madrid), Instituto de Salud Carlos III, Majadahonda, Spain
7. Red de Investigaci?n en Servicios de Salud en Enfermedades Cr?nicas (REDISSEC), Pamplona, Spain
8. The members of these networks are listed at the end of the article
Correspondence: Jes?s Castilla (jcastilc@navarra.es)
Citation style for this article: Castilla J, Navascu?s A, Fern?ndez-Alonso M, Reina G, Alb?niz E, Pozo F, ?lvarez N, Mart?nez-Baz I, Guevara M, Garc?a-Cenoz M, Irisarri F, Casado I, Ezpeleta C, Primary Health Care Sentinel Network and Network for Influenza Surveillance in Hospitals of Navarra. Effects of previous episodes of influenza and vaccination in preventing laboratory-confirmed influenza in Navarre, Spain, 2013/14 season. Euro Surveill. 2016;21(22):pii=30243. DOI: http://dx.doi.org/10.2807/1560-7917.ES.2016.21.22.30243
Received:27 July 2015; Accepted:25 February 2016
We estimated whether previous episodes of influenza and trivalent influenza vaccination prevented laboratory-confirmed influenza in Navarre, Spain, in season 2013/14. Patients with medically-attended influenza-like illness (MA-ILI) in hospitals (n = 645) and primary healthcare (n = 525) were included. We compared 589 influenza cases and 581 negative controls. MA-ILI related to a specific virus subtype in the previous five seasons was defined as a laboratory-confirmed influenza infection with the same virus subtype or MA-ILI during weeks when more than 25% of swabs were positive for this subtype. Persons with previous MA-ILI had 30% (95% confidence interval (CI): −7 to 54) lower risk of MA-ILI, and those with previous MA-ILI related to A(H1N1)pdm09 or A(H3N2) virus, had a, respectively, 63% (95% CI: 16?84) and 65% (95% CI: 13?86) lower risk of new laboratory-confirmed influenza by the same subtype. Overall adjusted vaccine effectiveness in preventing laboratory-confirmed influenza was 31% (95% CI: 5?50): 45% (95% CI: 12?65) for A(H1N1)pdm09 and 20% (95% CI: −16 to 44) for A(H3N2). While a previous influenza episode induced high protection only against the same virus subtype, influenza vaccination provided low to moderate protection against all circulating subtypes. Influenza vaccine remains the main preventive option for high-risk populations.
full article