| Methods |
Randomised controlled trial conducted in the USA during the 1993 to 1994 influenza season. Follow‐up was not indicated. Influenza period was not defined. Participants were randomly assigned to receive 1 of the following 5 vaccine preparations in a double‐blinded manner: 15 mg of rHA0, 15 mg of rHA0 plus alum, 90 mg of rHA0, licensed, and placebo. Spring sera were collected. |
| Participants |
59 healthy university students: 51 treated and 8 placebo. Age of participants was 18 to 45. |
| Interventions |
Subvirion monovalent parenteral vaccine. Schedule and dose were: single dose; 15 µg rHA0. Vaccine composition was: the recombinant HA vaccine contained HA0 glycoprotein from the influenza A/Beijing/32/92 (H3N2) virus. Placebo was saline for injection. Vaccine was not recommended but matched circulating strain. |
| Outcomes |
Clinical and laboratory‐confirmed cases. An "influenza‐like illness" was defined as the presence of any respiratory symptom(s) for >= 2 days, accompanied by fever or systemic symptoms of myalgia or chills. Laboratory evidence of influenza A (H3N2) virus infection was defined as either or both of the isolation of virus from nasopharyngeal secretion and a >= 4‐fold increase in serum HI antibody titre between the 3‐week postvaccination (preseason) specimen and the corresponding postseason specimen collected in the following spring. |
| Notes |
Efficacy data only were extracted. |
| 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 |
