| Study characteristics |
| Methods |
Authors investigated an outbreak in a nursing home in Canada during the 1982 to 1983 influenza season; partial surveillance for delayed notification of outbreak. Follow‐up period was 30 November 1982 to 9 January 1983. Throat swab and paired sera specimens were obtained from some residents. |
| Participants |
171 female, chronically ill nursing home residents (53 treated and 118 controls, all included in the analysis); 19 to 105 years old |
| Interventions |
Parenteral whole influenza vaccine: A/Brazil/11/78; A/Bangkok/1/79; B/Singapore/222/80. Vaccine strains probably matched circulating strains. |
| Outcomes |
Clinically defined ILI without further specification; death from pneumonia |
| Notes |
Poor reporting; no confounders control. Circulating strain: A/Bangkok/1/79‐like |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
B ‐ Unclear |
