| Study characteristics |
| Methods |
Case‐control study conducted in Italy during the 1994 to 1995 influenza season, in the community. Data sources were database discharge diagnoses and mailed questionnaire. Follow‐up period was 1 December 1994 to 31 March 1995. Cases were people discharged from hospital with pneumonia and influenza; community controls were matched for age, sex, and residence. |
| Participants |
825 residents of the province of Florence (275 cases and 550 controls were included in analysis; non‐response rate was 15% in each group), 65 years or older |
| Interventions |
Parenteral influenza vaccine. Vaccine strains did not match the circulating strain. |
| Outcomes |
Hospitalisation from pneumonia and influenza (ICD 480‐487) |
| Notes |
Pneumococcal vaccination was very unlikely. The season was an epidemic one. The study controls for confounders in analysis: disability, socio‐economic factors, and smoking habits. Quantitative analysis was also performed. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
B ‐ Unclear |
