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Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination
BACKGROUND: In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectivenes...
Autores principales: | , , , , , , , , , , , , , , , , , , |
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Formato: | Online Artículo Texto |
Lenguaje: | English |
Publicado: |
BioMed Central
2013
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Materias: | |
Acceso en línea: | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3848794/ https://www.ncbi.nlm.nih.gov/pubmed/24053661 http://dx.doi.org/10.1186/1471-2334-13-441 |
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author | Jiménez-Jorge, Silvia de Mateo, Salvador Delgado-Sanz, Concha Pozo, Francisco Casas, Inmaculada Garcia-Cenoz, Manuel Castilla, Jesús Pérez, Esteban Gallardo, Virtudes Rodriguez, Carolina Vega, Tomás Quiñones, Carmen Martínez, Eva Vanrell, Juana María Giménez, Jaume Castrillejo, Daniel Serrano, María del Carmen Ramos, Julián Mauro Larrauri, Amparo |
author_facet | Jiménez-Jorge, Silvia de Mateo, Salvador Delgado-Sanz, Concha Pozo, Francisco Casas, Inmaculada Garcia-Cenoz, Manuel Castilla, Jesús Pérez, Esteban Gallardo, Virtudes Rodriguez, Carolina Vega, Tomás Quiñones, Carmen Martínez, Eva Vanrell, Juana María Giménez, Jaume Castrillejo, Daniel Serrano, María del Carmen Ramos, Julián Mauro Larrauri, Amparo |
author_sort | Jiménez-Jorge, Silvia |
collection | PubMed |
description | BACKGROUND: In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza-like illness (ILI) among the target groups for vaccination in Spain in the 2011–2012 season. We also studied influenza VE in the early (weeks 52/2011-7/2012) and late (weeks 8-14/2012) phases of the epidemic and according to time since vaccination. METHODS: Medically attended patients with ILI were systematically swabbed to collect information on exposure, laboratory outcome and confounding factors. Patients belonging to target groups for vaccination and who were swabbed <8 days after symptom onset were included. Cases tested positive for influenza and controls tested negative for any influenza virus. To examine the effect of a late season, analyses were performed according to the phase of the season and according to the time between vaccination and symptoms onset. RESULTS: The overall adjusted influenza VE against A(H3N2) was 45% (95% CI, 0–69). The estimated influenza VE was 52% (95% CI, -3 to 78), 40% (95% CI, -40 to 74) and 22% (95% CI, -135 to 74) at 3.5 months, 3.5-4 months, and >4 months, respectively, since vaccination. A decrease in VE with time since vaccination was only observed in individuals aged ≥ 65 years. Regarding the phase of the season, decreasing point estimates were only observed in the early phase, whereas very low or null estimates were obtained in the late phase for the shortest time interval. CONCLUSIONS: The 2011–2012 influenza vaccine showed a low-to-moderate protective effect against medically attended, laboratory-confirmed influenza in the target groups for vaccination, in a late season and with a limited match between the vaccine and circulating strains. The suggested decrease in influenza VE with time since vaccination was mostly observed in the elderly population. The decreasing protective effect of the vaccine in the late part of the season could be related to waning vaccine protection because no viral changes were identified throughout the season. |
format | Online Article Text |
id | pubmed-3848794 |
institution | National Center for Biotechnology Information |
language | English |
publishDate | 2013 |
publisher | BioMed Central |
record_format | MEDLINE/PubMed |
spelling | pubmed-38487942013-12-04 Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination Jiménez-Jorge, Silvia de Mateo, Salvador Delgado-Sanz, Concha Pozo, Francisco Casas, Inmaculada Garcia-Cenoz, Manuel Castilla, Jesús Pérez, Esteban Gallardo, Virtudes Rodriguez, Carolina Vega, Tomás Quiñones, Carmen Martínez, Eva Vanrell, Juana María Giménez, Jaume Castrillejo, Daniel Serrano, María del Carmen Ramos, Julián Mauro Larrauri, Amparo BMC Infect Dis Research Article BACKGROUND: In Spain, the influenza vaccine effectiveness (VE) was estimated in the last three seasons using the observational study cycEVA conducted in the frame of the existing Spanish Influenza Sentinel Surveillance System. The objective of the study was to estimate influenza vaccine effectiveness (VE) against medically attended, laboratory-confirmed influenza-like illness (ILI) among the target groups for vaccination in Spain in the 2011–2012 season. We also studied influenza VE in the early (weeks 52/2011-7/2012) and late (weeks 8-14/2012) phases of the epidemic and according to time since vaccination. METHODS: Medically attended patients with ILI were systematically swabbed to collect information on exposure, laboratory outcome and confounding factors. Patients belonging to target groups for vaccination and who were swabbed <8 days after symptom onset were included. Cases tested positive for influenza and controls tested negative for any influenza virus. To examine the effect of a late season, analyses were performed according to the phase of the season and according to the time between vaccination and symptoms onset. RESULTS: The overall adjusted influenza VE against A(H3N2) was 45% (95% CI, 0–69). The estimated influenza VE was 52% (95% CI, -3 to 78), 40% (95% CI, -40 to 74) and 22% (95% CI, -135 to 74) at 3.5 months, 3.5-4 months, and >4 months, respectively, since vaccination. A decrease in VE with time since vaccination was only observed in individuals aged ≥ 65 years. Regarding the phase of the season, decreasing point estimates were only observed in the early phase, whereas very low or null estimates were obtained in the late phase for the shortest time interval. CONCLUSIONS: The 2011–2012 influenza vaccine showed a low-to-moderate protective effect against medically attended, laboratory-confirmed influenza in the target groups for vaccination, in a late season and with a limited match between the vaccine and circulating strains. The suggested decrease in influenza VE with time since vaccination was mostly observed in the elderly population. The decreasing protective effect of the vaccine in the late part of the season could be related to waning vaccine protection because no viral changes were identified throughout the season. BioMed Central 2013-09-22 /pmc/articles/PMC3848794/ /pubmed/24053661 http://dx.doi.org/10.1186/1471-2334-13-441 Text en Copyright © 2013 Jiménez-Jorge et al.; licensee BioMed Central Ltd. http://creativecommons.org/licenses/by/2.0 This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/2.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. |
spellingShingle | Research Article Jiménez-Jorge, Silvia de Mateo, Salvador Delgado-Sanz, Concha Pozo, Francisco Casas, Inmaculada Garcia-Cenoz, Manuel Castilla, Jesús Pérez, Esteban Gallardo, Virtudes Rodriguez, Carolina Vega, Tomás Quiñones, Carmen Martínez, Eva Vanrell, Juana María Giménez, Jaume Castrillejo, Daniel Serrano, María del Carmen Ramos, Julián Mauro Larrauri, Amparo Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title | Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title_full | Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title_fullStr | Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title_full_unstemmed | Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title_short | Effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in Spain, among population targeted for vaccination |
title_sort | effectiveness of influenza vaccine against laboratory-confirmed influenza, in the late 2011–2012 season in spain, among population targeted for vaccination |
topic | Research Article |
url | https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3848794/ https://www.ncbi.nlm.nih.gov/pubmed/24053661 http://dx.doi.org/10.1186/1471-2334-13-441 |
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