| Study characteristics |
| Methods |
Case‐control study conducted in Valencia, Spain during the 2002 to 2003 influenza season, in the community. Data sources were: hospital records; structured interview by trained field investigator. Follow‐up period was 15 November 2002 to 31 March 2003. Cases were people admitted to hospital for pneumonia; controls were admitted to hospital in the same week for acute abdominal surgical condition or trauma. |
| Participants |
815 non‐institutionalised people (325 cases and 525 controls were identified; 290 and 525 were included in analysis, respectively), 65 years or older |
| Interventions |
Parenteral influenza MF59 adjuvant vaccine. 42% of cases and 34% of controls received pneumococcal vaccination. Vaccine strains matched the circulating strain. |
| Outcomes |
Hospitalisation for pneumonia (ICD‐9 code 480‐487); pneumonia was clinically defined and radiologically confirmed |
| Notes |
The study controls for confounders in analysis: health status, smoking habits, pneumococcal vaccination. The season had low epidemic levels. Quantitative analysis was also performed. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
