The Importance of Staff Immunization in Long-Term Care Facilities

There is evidence that many frail elderly adults do not mount an adequate antibody response as a result of immunizations. This means that these adults continue to be at risk for development of influenza, even after administration of the vaccine. So far, no factors have been found that will predict which adults are less likely to respond to the vaccine (see the third abstract below).

Just because some adults do not respond to influenza vaccine does not mean that the vaccine should not be given. ACIP recommendations support administration of influenza vaccine to older adults. However, the continued vulnerability of many who reside in long-term care increases the importance of using additional strategies to protect this population.

A key strategy to protecting frail older adults in long-term care settings is to immunize the facility staff who come into contact with these residents. Long-term care facilities should strongly encourage staff to receive annual influenza immunizations. Strategies to support staff immunization, such as administration of the vaccine on-site and payment of the vaccine cost by the facility, should be seriously considered and implemented when possible.

Abstracts of four key articles relating to the importance of staff immunization are presented below.

1. Morens DM, Rash VM. Lessons from a nursing home outbreak of influenza A. Infect Control Hosp Edidemiol 1995 May;16(5):275-80.
   

OBJECTIVE: To characterize risk factors for outbreak-associated influenza illness and death in a nursing home. DESIGN: Outbreak investigation with predetermined and concurrently determined risk information. SETTING: A nursing home service in a multiward chronic care hospital, Honolulu, Oahu, 1989 to 1990. PATIENTS: Elderly nursing home patients receiving long-term care. INTERVENTIONS: Influenza vaccination, amantadine administration, and infection control measures. RESULTS: Neither routine infection control measures nor vaccination prevented illness, complications, or death in a nursing home outbreak of influenza A. The 55% case-fatality rate resulted from severe pneumonia. Influenza transmission may have been mediated by staff via either contaminated hands or fomites. CONCLUSIONS: Data from this and other outbreaks suggest that recommendations for preventing nosocomial influenza in the nation's 1.5 million nursing home residents should be reconsidered.

2. Potter JM, et.al. Influenza vaccination of health care workers in long-term care hospitals reduces the mortality of elderly patients. J Infect Dis 1997 Jan;175(1):1-6.

COMMENT: Comment in: ACP J Club 1997 Jul-Aug;127(1):

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.

3. Potter JM, et.al. Serological response to influenza vaccination and nutritional and functional status of patients in geriatric medical long-term care. Age Ageing - 1999 Mar; 28(2): 141-5.

INTRODUCTION: In the UK the Department of Health recommends influenza vaccination for elderly people resident in institutional care. However, the efficacy of vaccination may be reduced in very frail elderly people with functional impairment, undernutrition and multiple pathologies. Nutritional and functional status is claimed to affect vaccine responses in healthy elderly subjects. We wished to determine if a relationship could be seen between nutritional and functional status and seroconversion in patients receiving long-term care. METHODS: All patients in geriatric medical long-term care were offered vaccine. Consenting patients had pre- and post-vaccine serology measured using single radial hemolysis. Anthropometry was measured to enable body mass index (BMI) to be calculated. Functional independence was assessed using the 20-point Barthel index. RESULTS: Of 260 patients who received influenza vaccine, 137 (36 male, 101 female) consented to venesection for serology and thus form the study population. Mean age was 82 years (SD 7.9). The median Barthel score was 3/20 and the mean BMI was 21.6 (SD 4.6, range 13-36.2). Antibodies to influenza A were undetectable both pre- and post-vaccination in 63/137 patients. In 49 patients the antibody titre rose after vaccination and 25 had detectable antibody titres pre-vaccination which failed to rise post-vaccine. There were no significant associations between post-vaccination influenza antibody responses and BMI, Barthel score or age. CONCLUSION: Frail elderly patients in geriatric medical long-term care had a poor antibody response to influenza vaccination. Within this group, serological responses could not be predicted by nutritional or functional status.

4. Carman WF, Elder AG, Wallace LA, et al. Effects of influenza vaccination of health-care workers on mortality of elderly people in long-term care: a randomized controlled trial Lancet 2000;355:93-97.

BACKGROUND: 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.  METHODS: 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. FINDINGS: 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). INTERPRETATION: 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.