| Study characteristics |
| Methods |
Authors investigated an outbreak in a nursing home, in Atlanta, USA, during the 1984 to 1985 influenza season; active surveillance; medical records were reviewed. Follow‐up period was 26 January 1985 to 1 February 1985. Pharyngeal swab and paired sera were collected to confirm diagnosis. |
| Participants |
55 nursing home residents (31 treated and 24 controls, all included in the analysis), mean age 85 years |
| Interventions |
Parenteral influenza vaccine: A/Philippines/2/82, A/Chile/83, B/USSR/84. Vaccine strains probably matched circulating strains. |
| Outcomes |
Clinically defined ILI (fever 38.7 °C or greater, cough, coryza, sore throat); hospitalisation from ILI; ILI severity (not extracted) |
| Notes |
7 days after the outbreak started, all residents were given amantadine. Successive outcomes were not accounted for. The circulating strain was related to A/Philippines/2/82. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
B ‐ Unclear |
