| Study characteristics |
| Methods |
Authors investigated an outbreak in a skilled nursing home, in New York, USA during the 1987 to 1988 influenza season; individual charts were reviewed. Follow‐up period was 26 December 1987 to 25 January 1988. Throat swab and paired sera specimens were obtained from some ill residents. |
| Participants |
124 nursing home residents (112 treated and 12 controls, all included in the analysis), 20 to 100 years old (mean age 85 years). 105 participants had 1 or more underlying medical conditions. |
| Interventions |
Parenteral influenza vaccine: A/Taiwan/1/86; A/Leningrad/360/86; B/Ann Arbor/1/86. Vaccine strains did not match the circulating strain. |
| Outcomes |
Clinically defined ILI (fever 100 °F or greater, cough, coryza, sore throat, pneumonia); pneumonia; hospitalisation from ILI; flu‐related deaths |
| Notes |
Vaccinated and not vaccinated participants were similar as underlying conditions. The circulating strain was Shanghai/11/87. Only 1 participant received amantadine prophylaxis. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
