| Study characteristics |
| Methods |
Experimental study conducted in New York, USA during the 1990 to 1991 influenza season, randomised, double‐blind, placebo‐controlled study. 34 participants received live vaccine; 30 participants received trivalent vaccine; 11 participants received placebo. Follow‐up period was for 7 days after vaccination. Participants filled self administered diary card. |
| Participants |
75 outpatients with chronic disease or elderly, mostly 65 years or older |
| Interventions |
Live cold‐adapted influenza B virus vaccine, aerosol administered; parenteral trivalent influenza vaccine |
| Outcomes |
Upper respiratory symptoms (coryza or sore throat), lower respiratory symptoms (cough, hoarseness, or dyspnoea), systemic symptoms (malaise and myalgia), sore arm, fever |
| Notes |
Participants experiencing symptoms within 1 week of vaccination were considered. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Random sequence generation (selection bias) |
Unclear risk |
Randomisation method not described. |
| Allocation concealment (selection bias) |
Unclear risk |
Allocation concealment not described. |
| Blinding (performance bias and detection bias)
All outcomes |
Unclear risk |
Described as placebo controlled, but no further details available |
| Incomplete outcome data (attrition bias)
All outcomes |
Low risk |
No attrition |
