| Study characteristics |
| Methods |
Retrospective cohort study conducted in the UK during the 1990 to 1998 influenza season, in the community. Data source was a managed care organisation database. Follow‐up period was the epidemic period (period with consultation rate for ILI more than 50/100,000 person‐weeks). People were identified and included in the study if they were registered on the first day of the week that included 1 September each year. |
| Participants |
692,819 person‐years in vaccine recipients and 1,534,280 person‐years in vaccine non‐recipients, 65 years or older |
| Interventions |
Parenteral influenza vaccine |
| Outcomes |
Hospitalisation for acute respiratory illness (ICD 466, 480‐487), respiratory‐related deaths |
| Notes |
Most of the seasons were epidemic, with vaccine strains matching the circulating strains. Data were presented by health status; other strata: year, flu activity, age. Data by health status were extracted by rates reported in tables. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
