Estimates of pandemic influenza vaccine effectiveness in Europe, 2009-2010: results of Influenza Monitoring Vaccine Effectiveness in Europe (I-MOVE) multicentre case-control study

• Published in: PLoS medicine 2011-01, Vol.8 (1), p.e1000388-e1000388
• Main Authors: Valenciano, Marta, Kissling, Esther, Cohen, Jean-Marie, Oroszi, Beatrix, Barret, Anne-Sophie, Rizzo, Caterina, Nunes, Baltazar, Pitigoi, Daniela, Larrauri Cámara, Amparro, Mosnier, Anne, Horvath, Judith K, O'Donnell, Joan, Bella, Antonino, Guiomar, Raquel, Lupulescu, Emilia, Savulescu, Camelia, Ciancio, Bruno C, Kramarz, Piotr, Moren, Alain
• Format: Article
• Language: English
• Subjects: Adult; Aged; Case-Control Studies; Child; Child, Preschool; Estimates; Europe - epidemiology; Female; Humans; Immunization; Infant; Infectious Diseases/Epidemiology and Control of Infectious Diseases; Influenza; Influenza A Virus, H1N1 Subtype; Influenza Vaccines; Influenza, Human - epidemiology; Influenza, Human - prevention & control; Influenza, Human - virology; Logistic Models; Male; Middle Aged; Odds Ratio; Outcome Assessment (Health Care); Pandemics - prevention & control; Public Health and Epidemiology/Immunization; Public Health and Epidemiology/Infectious Diseases; Sentinel Surveillance; Studies; Vaccines; Young Adult
• ISSN: 1549-1676; 1549-1277; 1549-1676
• DOI: 10.1371/journal.pmed.1000388

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). 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