| Study characteristics |
| Methods |
Prospective cohort study conducted in Japan during the 1999 to 2000 influenza season in 11 nursing homes. Follow‐up period was the epidemic period. Efficacy assessment was also performed by vaccination rate in residents and HCWs, physical impairment, sex, age, and health status of residents. Throat swabs were obtained from ill individuals; medical charts were reviewed. |
| Participants |
930 residents in 11 nursing homes (743 treated and 187 controls, all included in the analysis). The vaccinated group had more physical impairment of daily living. |
| Interventions |
Parenteral influenza vaccine: A/Beijing/262/95; A/Sydney/5/97; B/Shandon/7/97. Vaccine strains matched circulating strains (good match). |
| Outcomes |
Clinically defined ILI (fever + cough or coryza or sore throat) occurring during the epidemic period |
| Notes |
The circulating strain was A/Sydney. Influenza virus exposure was confirmed in only 4/11 facilities. No outbreaks were detected. No other respiratory viruses were isolated. Data were extracted by RRs reported in tables. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Unclear risk |
B ‐ Unclear |
