tetano
Editor, Senior Moderator
Marta Valenciano1*, Esther Kissling1, Jean-Marie Cohen2, Beatrix Oroszi3, Anne-Sophie Barret4,5, Caterina Rizzo6, Baltazar Nunes7, Daniela Pitigoi8,9, Amparro Larrauri C?mara10, Anne Mosnier2, Judith K. Horvath3, Joan O'Donnell4, Antonio Bella6, Raquel Guiomar7, Emilia Lupulescu8, Camelia Savulescu1,10, Bruno C. Ciancio11, Piotr Kramarz11, Alain Moren1
1 EpiConcept, Paris, France, 2 R?seau des GROG/Open Rome, Paris, France, 3 National Center for Epidemiology, Budapest, Hungary, 4 Health Protection Surveillance Centre, Dublin, Ireland, 5 European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden, 6 National Centre for Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanit?, Roma, Italy, 7 Instituto Nacional de Sa?de Dr Ricardo Jorge, Lisbon, Portugal, 8 Cantacuzino Institute, National Institute of Research ? Development for Microbiology and Immunology, Bucharest, Romania, 9 Universitatea de Medicina si Farmacie Carol Davila, Bucharest, Romania, 10 National Centre for Epidemiology, Instituto de Salud Carlos III, Madrid, Spain, 11 European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
Background
A multicentre case-control study based on sentinel practitioner surveillance networks from seven European countries was undertaken to estimate the effectiveness of 2009?2010 pandemic and seasonal influenza vaccines against medically attended influenza-like illness (ILI) laboratory-confirmed as pandemic influenza A (H1N1) (pH1N1).
Methods and Findings
Sentinel practitioners swabbed ILI patients using systematic sampling. We included in the study patients meeting the European ILI case definition with onset of symptoms >14 days after the start of national pandemic vaccination campaigns. We compared pH1N1 cases to influenza laboratory-negative controls. A valid vaccination corresponded to >14 days between receiving a dose of vaccine and symptom onset. We estimated pooled vaccine effectiveness (VE) as 1 minus the odds ratio with the study site as a fixed effect. Using logistic regression, we adjusted VE for potential confounding factors (age group, sex, month of onset, chronic diseases and related hospitalizations, smoking history, seasonal influenza vaccinations, practitioner visits in previous year). We conducted a complete case analysis excluding individuals with missing values and a multiple multivariate imputation to estimate missing values. The multivariate imputation (n = 2902) adjusted pandemic VE (PIVE) estimates were 71.9% (95% confidence interval [CI] 45.6?85.5) overall; 78.4% (95% CI 54.4?89.8) in patients <65 years; and 72.9% (95% CI 39.8?87.8) in individuals without chronic disease. The complete case (n = 1,502) adjusted PIVE were 66.0% (95% CI 23.9?84.8), 71.3% (95% CI 29.1?88.4), and 70.2% (95% CI 19.4?89.0), respectively. The adjusted PIVE was 66.0% (95% CI −69.9 to 93.2) if vaccinated 8?14 days before ILI onset. The adjusted 2009?2010 seasonal influenza VE was 9.9% (95% CI −65.2 to 50.9).
Conclusions
Our results suggest good protection of the pandemic monovalent vaccine against medically attended pH1N1 and no effect of the 2009?2010 seasonal influenza vaccine. However, the late availability of the pandemic vaccine and subsequent limited coverage with this vaccine hampered our ability to study vaccine benefits during the outbreak period. Future studies should include estimation of the effectiveness of the new trivalent vaccine in the upcoming 2010?2011 season, when vaccination will occur before the influenza season starts.
http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000388
1 EpiConcept, Paris, France, 2 R?seau des GROG/Open Rome, Paris, France, 3 National Center for Epidemiology, Budapest, Hungary, 4 Health Protection Surveillance Centre, Dublin, Ireland, 5 European Programme for Intervention Epidemiology Training (EPIET), European Centre for Disease Prevention and Control, Stockholm, Sweden, 6 National Centre for Epidemiology, Surveillance and Health Promotion, Istituto Superiore di Sanit?, Roma, Italy, 7 Instituto Nacional de Sa?de Dr Ricardo Jorge, Lisbon, Portugal, 8 Cantacuzino Institute, National Institute of Research ? Development for Microbiology and Immunology, Bucharest, Romania, 9 Universitatea de Medicina si Farmacie Carol Davila, Bucharest, Romania, 10 National Centre for Epidemiology, Instituto de Salud Carlos III, Madrid, Spain, 11 European Centre for Disease Prevention and Control (ECDC), Stockholm, Sweden
Background
A multicentre case-control study based on sentinel practitioner surveillance networks from seven European countries was undertaken to estimate the effectiveness of 2009?2010 pandemic and seasonal influenza vaccines against medically attended influenza-like illness (ILI) laboratory-confirmed as pandemic influenza A (H1N1) (pH1N1).
Methods and Findings
Sentinel practitioners swabbed ILI patients using systematic sampling. We included in the study patients meeting the European ILI case definition with onset of symptoms >14 days after the start of national pandemic vaccination campaigns. We compared pH1N1 cases to influenza laboratory-negative controls. A valid vaccination corresponded to >14 days between receiving a dose of vaccine and symptom onset. We estimated pooled vaccine effectiveness (VE) as 1 minus the odds ratio with the study site as a fixed effect. Using logistic regression, we adjusted VE for potential confounding factors (age group, sex, month of onset, chronic diseases and related hospitalizations, smoking history, seasonal influenza vaccinations, practitioner visits in previous year). We conducted a complete case analysis excluding individuals with missing values and a multiple multivariate imputation to estimate missing values. The multivariate imputation (n = 2902) adjusted pandemic VE (PIVE) estimates were 71.9% (95% confidence interval [CI] 45.6?85.5) overall; 78.4% (95% CI 54.4?89.8) in patients <65 years; and 72.9% (95% CI 39.8?87.8) in individuals without chronic disease. The complete case (n = 1,502) adjusted PIVE were 66.0% (95% CI 23.9?84.8), 71.3% (95% CI 29.1?88.4), and 70.2% (95% CI 19.4?89.0), respectively. The adjusted PIVE was 66.0% (95% CI −69.9 to 93.2) if vaccinated 8?14 days before ILI onset. The adjusted 2009?2010 seasonal influenza VE was 9.9% (95% CI −65.2 to 50.9).
Conclusions
Our results suggest good protection of the pandemic monovalent vaccine against medically attended pH1N1 and no effect of the 2009?2010 seasonal influenza vaccine. However, the late availability of the pandemic vaccine and subsequent limited coverage with this vaccine hampered our ability to study vaccine benefits during the outbreak period. Future studies should include estimation of the effectiveness of the new trivalent vaccine in the upcoming 2010?2011 season, when vaccination will occur before the influenza season starts.
http://www.plosmedicine.org/article/info:doi/10.1371/journal.pmed.1000388