| Study characteristics |
| Methods |
Authors investigated an outbreak in a multiple‐level care facility in Connecticut, USA, during the 1984 to 1985 influenza season; medical records were reviewed. Follow‐up period was 1 February 1985 to 10 April 1985. Throat swab and paired sera specimens were obtained from some ill residents. |
| Participants |
458 residents (332 treated and 151 controls, 332 and 126 included in the analysis respectively), 64 to 104 years old |
| Interventions |
Parenteral influenza vaccine: A/Philippines/2/82; A/Chile/83; B/USSR/100/84. Vaccine strains probably matched circulating strains. |
| Outcomes |
Clinically defined ILI (fever 37.8 °C or greater, cough, coryza, sore throat); hospitalisation from ILI; deaths occurring within 2 weeks of ILI with no other explanation |
| Notes |
42 days after the outbreak started amantadine prophylaxis was given to most of the remaining well residents. 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 |
