| Study characteristics |
| Methods |
Prospective cohort study conducted in Melbourne, Australia during the 1976 influenza season. Authors investigated an outbreak in a nursing home. Follow‐up period was from mid‐April to mid‐August. Throat swabs and paired sera specimens were obtained from residents. |
| Participants |
222 nursing home residents (154 treated and 68 controls, all included in the analysis); elderly |
| Interventions |
Parenteral influenza vaccine: A/Victoria/3/75; A/Scotland/840/74; B/Hong Kong/8/73. Vaccine strains matched circulating strains. |
| Outcomes |
Laboratory‐confirmed influenza, deaths from influenza |
| Notes |
Poor reporting; no confounders control. The circulating strain was A/Victoria/3/75. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
High risk |
C ‐ Inadequate |
