| Study characteristics |
| Methods |
Authors investigated an outbreak in a nursing home in Los Angeles, USA during the 1982 to 1983 influenza season; patients records were reviewed. Follow‐up period was 1 February 1983 to 31 March 1983. Virus circulation was confirmed with throat swab from ill people. |
| Participants |
87 nursing home residents, 59 to 94 years old, most of them suffering from dementia (65 treated and 19 controls were included in the analysis; vaccination status could not be determined for 3 residents) |
| Interventions |
Parenteral influenza vaccine: A/Bangkok/79; A/Brazil/78; B/Singapore/79. Vaccine strains probably matched circulating strains. |
| Outcomes |
Clinically defined ILI (fever or fever + respiratory symptoms) occurring during the epidemic period, deaths from ILI |
| Notes |
Age, sex ratio, and health status were similar in vaccinated and unvaccinated people. The circulating strain was A/Bangkok/79‐like. No other positive laboratory findings were found. Amantadine was not used. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
