| Study characteristics |
| Methods |
Prospective cohort study conducted in Spain during the 1984 to 1985 influenza season, in the community. Data source was a questionnaire retrospectively applied by investigators in June to July 1985 (door‐to‐door survey). The whole population of a rural village was investigated. |
| Participants |
268 community‐dwelling (188 treated and 80 controls, all included in the analysis), 65 years or older |
| Interventions |
Parenteral influenza vaccine: A/Philippines/2/82; A/Chile/1/83; B/USSR/100/83. Matching unknown. |
| Outcomes |
Clinically defined ILI (fever 39 °C or more, chills, general malaise, myalgia, headache, arthralgia, conjunctivitis, lasting 3 days or more) |
| Notes |
None of the observed deaths was due to flu‐related illness. The season had low epidemic levels. Subgroup analysis was performed but only for the whole population. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
High risk |
C ‐ Inadequate |
