Effect of influenza vaccination of nursing home staff on mortality of residents: a cluster-randomized trial. Additive preventive effect of influenza and pneumococcal vaccines in elderly persons. Effectiveness of influenza vaccination in preventing influenza-like illness among community-dwelling elderly: population-based cohort study in Japan. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomised controlled trial. Influenza vaccination of health care workers in long-term-care hospitals reduces the mortality of elderly patients.
To evaluate the effect of staff influenza vaccination on all-cause mortality in nursing home residents.
                Pair-matched cluster-randomized trial.
                Forty nursing homes matched for size, staff vaccination coverage during the previous season, and resident disability index.
                All persons aged 60 and older residing in the nursing homes.
                Influenza vaccine was administered to volunteer staff after a face-to-face interview. No intervention took place in control nursing homes.
                The primary endpoint was total mortality rate in residents from 2 weeks before to 2 weeks after the influenza epidemic in the community. Secondary endpoints were rates of hospitalization and influenza-like illness (ILI) in residents and sick leave from work in staff.
                Staff influenza vaccination rates were 69.9% in the vaccination arm versus 31.8% in the control arm. Primary unadjusted analysis did not show significantly lower mortality in residents in the vaccination arm (odds ratio=0.86, P=.08), although multivariate-adjusted analysis showed 20% lower mortality (P=.02), and a strong correlation was observed between staff vaccination coverage and all-cause mortality in residents (correlation coefficient=-0.42, P=.007). In the vaccination arm, significantly lower resident hospitalization rates were not observed, but ILI in residents was 31% lower (P=.007), and sick leave from work in staff was 42% lower (P=.03).
                These results support influenza vaccination of staff caring for institutionalized elderly people. In 1999, all individuals > or = 65 yrs of age (n=258,754) in Stockholm County, Sweden, were offered influenza and pneumococcal vaccination in a prospective study on the effectiveness of these vaccines in reducing the need for hospital treatment and death due to influenza, pneumonia and invasive pneumococcal disease (IPD). Data on hospitalisation and mortality during 1 yr were obtained from the administrative database in Stockholm County Council. Vaccination was performed in 124,702 (48%) subjects; 72,107 had both vaccines, 29,346 only had the influenza vaccine and 23,249 only had the pneumococcal vaccine. Compared with the unvaccinated cohort, a lower incidence of hospitalisation for all endpoint diagnoses was seen in vaccinated persons. An additive effectiveness of vaccination was seen when both vaccines were given, with a reduction of hospital admissions for influenza (37%), pneumonia (29%) and IPD (44%). In-hospital mortality for pneumonia was significantly lower in those who received both vaccines, than in unvaccinated persons. To conclude, vaccination with influenza and pneumococcal vaccines together was effective in reducing the need for hospital admission for influenza and pneumonia. There was a strong indication that pneumococcal vaccination alone, was effective not only in the prevention of invasive pneumococcal disease, but also of pneumonia overall, although to a low degree. A population-based cohort study was conducted during the 2003-2004 season to examine the effectiveness of influenza vaccine among community-dwelling elderly. The subjects consisted of 4787 elderly, ranging from 65 to 79 years. We either interviewed the elderly directly or their families regarding acute febrile illness, hospital visits, hospitalization and death by telephone every month. The vaccination status and physician-diagnosed clinical influenza (hereinafter referred as clinical influenza) were determined based on data obtained from the city office and hospitals, respectively. Influenza-like illness (ILI) was defined as an acute febrile illness (> or = 38.5 degrees C) during the epidemic period. After adjusting for confounders, vaccination decreased ILI significantly (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.17-0.85), but not clinical influenza (OR, 0.76; 95% CI, 0.28-2.06). The results were inconclusive for preventing hospitalization for influenza or pneumonia (OR, 0.37; 95% CI, 0.09-1.47) and death (OR, 3.68; 95% CI, 0.75-18.12), due to the inadequate sample size. In conclusion, the influenza vaccination was thus found to be associated with a decreased ILI during the epidemic period in community-dwelling elderly. Vaccination of health-care workers has been claimed to prevent nosocomial influenza infection of elderly patients in long-term care. Data are, however, limited on this strategy. We aimed to find out whether vaccination of health-care workers lowers mortality and the frequency of virologically proven influenza in such patients.
                In a parallel-group study, health-care workers in 20 long-term elderly-care hospitals (range 44-105 patients) were randomly offered or not offered influenza vaccine (cluster randomisation, stratified for policy for vaccination of patients and hospital size). All deaths among patients were recorded over 6 months in the winter of 1996-97. We selected a random sample of 50% of patients for virological surveillance for influenza, with combined nasal and throat swabs taken every 2 weeks during the epidemic period. Swabs were tested by tissue culture and PCR for influenza viruses A and B.
                Influenza vaccine uptake in health-care workers was 50.9% in hospitals in which they were routinely offered vaccine, compared with 4.9% in those in which they were not. The uncorrected rate of mortality in patients was 102 (13.6%) of 749 in vaccine hospitals compared with 154 (22.4%) of 688 in no-vaccine hospitals (odds ratio 0.58 [95% CI 0.40-0.84], p=0.014). The two groups did not differ for proportions of patients positive for influenza infection (5.4% and 6.7%, respectively); at necropsy, PCR was positive in none of 17 patients from vaccine hospitals and six (20%) of 30 from no-vaccine hospitals (p=0.055).
                Vaccination of health-care workers was associated with a substantial decrease in mortality among patients. However, virological surveillance showed no associated decrease in non-fatal influenza infection in patients. Vaccination of health care workers (HCWs) is recommended as a strategy for preventing influenza in elderly patients in long-term care. However, there have been no controlled studies to show whether this approach is effective. During the winter of 1994-1995, 1059 patients in 12 geriatric medical long-term-care sites, randomized for vaccination of HCWs, were studied. In hospitals where HCWs were offered vaccination, 653 (61%) of 1078 were vaccinated. Vaccination of HCWs was associated with reductions in total patient mortality from 17% to 10% (odds ratio [OR], 0.56; 95% confidence interval [CI], 0.40-0.80) and in influenza-like illness (OR, 0.57; 95% CI, 0.34-0.94). Vaccination of patients was not associated with significant effects on mortality (OR, 1.15; 95% CI, 0.81-1.64). Results of this study support recommendations for vaccination against influenza of HCWs in long-term geriatric care. Vaccination of frail elderly long-term-care patients may not give clinically worthwhile benefits.
No effect was shown for specific outcomes: laboratory-proven influenza, pneumonia and death from pneumonia. An effect was shown for the non-specific outcomes of ILI, GP consultations for ILI and all-cause mortality in individuals ≥ 60. These non-specific outcomes are difficult to interpret because ILI includes many pathogens, and winter influenza contributes < 10% to all-cause mortality in individuals ≥ 60. The key interest is preventing laboratory-proven influenza in individuals ≥ 60, pneumonia and deaths from pneumonia, and we cannot draw such conclusions.
The identified studies are at high risk of bias.
Some HCWs remain unvaccinated because they do not perceive risk, doubt vaccine efficacy and are concerned about side effects. This review did not find information on co-interventions with HCW vaccination: hand washing, face masks, early detection of laboratory-proven influenza, quarantine, avoiding admissions, anti-virals, and asking HCWs with ILI not to work. We conclude there is no evidence that vaccinating HCWs prevents influenza in elderly residents in LTCFs. High quality RCTs are required to avoid risks of bias in methodology and conduct, and to test these interventions in combination.