| Study characteristics |
| Methods |
Authors investigated an outbreak in a nursing home in Canada during the 1982 to 1983 influenza season; active surveillance. Follow‐up period was 3 November 1982 to 17 January 1983. Throat swab and paired sera specimens were obtained from some residents. |
| Participants |
545 chronically ill nursing home residents (321 treated and 224 controls, all included in the analysis); 18 to 103 years old, mean age 80 years |
| Interventions |
Parenteral influenza vaccine, whole and subvirion: A/Brazil/11/78; A/Bangkok/1/79; B/Singapore/222/79. Vaccine strains probably matched circulating strains. |
| Outcomes |
Acute respiratory symptoms: fever, congestion, cough, sore throat, general malaise, without a clear definition; death from pneumonia |
| Notes |
Poor reporting; no confounders control. Circulating strain: A/Bangkok/1/79‐like; no other viruses were identified |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
B ‐ Unclear |
