| Methods |
Multicentre, randomised, placebo‐controlled trial assessing the effectiveness of both inactivated and live attenuated vaccines in preventing laboratory‐confirmed influenza in healthy adults aged below 50 years. Same methods as aa Ohmit 2006. |
| Participants |
For study year 2005 to 2006, healthy men and women aged 18 to 48 years were recruited at 6 study sites (4 university sites and 2 community sites) in Michigan. In all 2058 participants were enrolled. Of these, 972 were already enrolled in the 2004 to 2005 season (see aa Ohmit 2006). |
| Interventions |
Participants who were enrolled in the 2005 to 2006 season were randomised (see aa Ohmit 2006) to receive inactivated vaccine (Fluzone; Sanofi Pasteur), live attenuated vaccine (FluMist; MedImmune), or placebo. Participants already enrolled in the 2004 to 2005 season received the same intervention type (i.e. Fluzone, FluMist, or placebo) as before.
Fluzone (intramuscularly administered) contained 15 g haemagglutinin from each of the following strains: A/New Caledonia/20/99 (H1N1), A/New York/55/2004 (H3N2) (A/California/7/2004‐like), and B/Jiangsu/10/2003 (B/Shanghai/361/2002‐like). FluMist (intranasally administered) was formulated to contain a median tissue‐culture infective dose of 106.5 to 107.5 live attenuated influenza virus reassortants of the same strains. Intramuscular or intranasal saline placebo.
|
| Outcomes |
Local and systemic reactions within 7 days from immunisation (see Ohmit 2006). Symptomatic laboratory‐confirmed influenza A or B illness (primary efficacy outcome). Symptoms were defined as at least 1 respiratory symptom (cough or nasal congestion) plus at least 1 systemic symptom (fever or feverishness, chills, or body aches). Laboratory confirmation was assessed by isolation of the influenza virus in cell culture or by comparison of paired postvaccination (preseason) and postseason serum with at least a 4‐fold increase in haemagglutination‐inhibition antibody titre to 1 circulating influenza strain. Illnesses confirmed by identification of the virus in real‐time PCR assays was considered as a secondary efficacy outcome. |
| Notes |
Government funded |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Unclear |
| Allocation concealment (selection bias) |
Unclear risk |
Unclear |
| Blinding (performance bias and detection bias)
All outcomes |
Unclear risk |
Unclear |
| Incomplete outcome data (attrition bias)
All outcomes |
Unclear risk |
Unclear |
| Summary assessment |
Unclear risk |
Unclear |
