| Study characteristics |
| Methods |
Authors investigated 2 consecutive outbreaks in the same nursing home in Japan during the 1996 to 1997 influenza season; patients' records were reviewed. Follow‐up period was 25 December 1996 to 14 January 1997 and 19 February 1997 to 26 February 1997. Throat swab and paired sera specimens were obtained from ill residents. |
| Participants |
128 nursing home residents (60 treated and 68 controls, all included in the analysis), 70 years or older. None of the residents was previously vaccinated. |
| Interventions |
2 doses of parenteral influenza vaccine: A/Yamagata/32/89; A/Wuhan/359/95; B/Mie/1/93. Vaccine strains matched circulating strains. |
| Outcomes |
ICHPP‐2 defined ILI (laboratory evidence or epidemiological criteria or 6 of the following symptoms: sudden onset, fever, cough, prostration, chills, weakness, myalgia, widespread aches), hospitalisations, and deaths without definition |
| Notes |
Epidemic reoccurrence of influenza A outbreak was observed. Both outbreaks were investigated; vaccinated and control groups were comparable as age or risk status. The circulating strain was A/Wuhan/359/95. Amantadine was not used. Other respiratory viruses were not isolated. |
| Risk of bias |
| Bias |
Authors' judgement |
Support for judgement |
| Allocation concealment (selection bias) |
Low risk |
A ‐ Adequate |
