Pooled crude and adjusted seasonal vaccine effectiveness against all influenza, A(H1N1)2009 and influenza B, overall and by age group, imputed data, I-MOVE multi-centre case control study, influenza season 2010-11.

‡Study site included in the model as fixed effect.∫Model adjusted for 2009-10 seasonal and pandemic influenza vaccination, presence of at least one chronic disease, sex, at least one hospitalisation for chronic disease in the previous 12 months, current smoker, age group (10 year bands), practitioner visits in previous 12 months (0-1, 2-4 and 5+ visits), week of symptom onset.NB: For influenza B imputed analysis, we are obliged to drop week 14 (1 record) in order to do computation.For the certain analyses, weeks of onset had to be dropped due to only positive or negative outcomes during this week.1Weeks 13 and 14 dropped (8 records dropped).2Week 14 dropped (2 records dropped).3Weeks 46 and 14 dropped (5 records dropped).4Weeks 12, 13 and 14 dropped (8 records dropped).5Week 14 dropped (1 record dropped).6Weeks 48,49 and 10-14 dropped (28 records dropped).7Week 13 dropped (4 records dropped).8Week 49 dropped (14 records dropped).9Weeks 46 and 50 dropped (14 records dropped).