Influenza in long-term care facilities: Preventable, detectable, treatable
ABSTRACTInfluenza in long-term care facilities is an ever more challenging problem. Vaccination of residents and health care workers is the most important preventive measure. Although vaccine efficacy has been questioned, the preponderance of data favors vaccination. Antiviral resistance complicates postexposure chemoprophylaxis and treatment. Factors that limit the choice of antiviral agents in this patient population include limited vaccine supplies and impaired dexterity and confusion in long-term care residents.
KEY POINTS
- When health care workers in long-term care facilities are vaccinated against influenza, significantly fewer residents die or develop influenza-like illness, particularly when residents are also vaccinated.
- Easily accessible dispensers for alcohol-based antiseptic foam or gel can significantly improve hand hygiene rates in health care workers.
- If a patient in a long-term care facility is visibly coughing and cannot cover his or her mouth, health care workers should wear a mask when within 3 feet of the patient.
- All isolates of pandemic influenza A/H1N1 (previously called swine-origin influenza virus) are susceptible to zanamivir (Relenza) and oseltamivir (Tamiflu), but are resistant to amantadine (Symmetrel) and rimantadine (Flumadine).
Vaccination works, despite the controversy
Whether influenza vaccination prevents deaths in elderly people—or how many deaths it prevents—is a subject of ongoing controversy. 16 Even though influenza vaccination coverage in the elderly increased from 15% to 65% since 1980, the specific influenza-related death rate did not decrease.17
It has been suggested that cohort studies may have overestimated the mortality benefit of influenza vaccination in the elderly because of “frailty selection bias” (ie, extremely frail elderly patients are less likely to be vaccinated and are more likely to die for reasons other than influenza than are less frail, vaccinated elderly people) and because of the use of nonspecific end points such as all-cause mortality. 16 Similarly, observational studies may have overestimated the in-hospital mortality benefit of influenza vaccination in older patients with pneumonia occurring outside of influenza season because of the “healthy user effect” (ie, residual confounding by functional and socioeconomic status).18
One nested case-control study in immunocompetent elderly patients showed that influenza vaccination was not associated with a reduced risk of community-acquired pneumonia after adjusting for the presence and severity of comorbidities.19
Since death is a rare end point, it is hard to show a reduction in the death rate with vaccination in randomized controlled studies. The absolute risk reduction in hospitalization and death with vaccination is two to five times higher in elderly patients at high risk than in the healthy elderly.20
The mortality benefit in elderly patients is increased with annual revaccination, with one death prevented for every 300 vaccinations, and one for every 200 revaccinations.21
The response to influenza vaccination is reduced in elderly people because of immune senescence, and higher doses of vaccine have been shown to be more immunogenic and remain safe.22 This enhanced antibody response may be maintained for subsequent antigenically different influenza variants, even against viruses appearing more than 10 years after vaccination. 23 The 2008–2009 influenza vaccine does not protect against the new, pandemic influenza A/H1N1 variant; efforts to produce such a vaccine are under way.
Influenza vaccination is safe. Recent data showed no association between immunization and Guillain-Barré syndrome.24 In fact, influenza itself may be a triggering agent for Guillain-Barré syndrome during major influenza outbreaks.25
DURATION OF SEROPROTECTION IS MORE THAN 6 MONTHS
Every effort should be made to vaccinate residents of long-term care facilities and their caregivers as early as possible in the influenza season to allow an adequate antibody response to develop before the onset of an influenza outbreak.
In the past, there has been concern that the influenza-vaccine-induced antibody response declines more rapidly in the elderly and may fall below seroprotective levels within 4 months of vaccination. But a recent review of 14 published studies argued against that notion, showing that if seroprotection is achieved in the first month after vaccination, it is then maintained for more than 6 months.26 That review also showed that seroconversion varies inversely with preimmunization titers, but not with age.
Moreover, a prospective study27 in 303 residents of a long-term care facility reported that seroprotection did not correlate with nutritional status. In the study, vaccination was very effective despite a high prevalence of nutritional deficiencies. This study also indicated that although an influenza antibody titer greater than 1:40 is considered protective in the general population, long-term care facility residents may require higher levels for effective immunization.
A recent survey showed that a national shortage of influenza vaccine results in decreased immunization rates in residents and in health care workers in long-term care facilities. 28 In that survey, only 2.3% of facilities expressed concern about emergency preparedness, and this has significant implications for a possible influenza pandemic.
VACCINATION PROGRAMS
Standing-order programs have been shown to significantly increase vaccination rates in ambulatory and hospital settings. However, a recent survey showed that only 9% of long-term care facilities use such programs.29 The greatest use of such programs was in government-owned, nonprofit, dual-certified (ie, by both Medicare and Medicaid), and independent long-term care facilities, and in facilities with a lower index of disease acuity. Use varied substantially by state.
The Healthy People 2010 goal of 90% vaccination may be attained by implementing written protocols for documenting immunization—and refusal of immunization—in a consistent place in the patient’s medical record.30
VACCINATION OF WORKERS
When health care workers in long-term care facilities are vaccinated against influenza, significantly fewer residents die31,32 or develop influenza-like illness, particularly when residents themselves are vaccinated.33 Additional benefits include decreased need for consultations with general practitioners or admissions to the hospital for influenza-like illness during periods of moderate influenza activity.32
The policy of mandatory influenza vaccination for health care workers has its proponents34 and opponents.35 When a large tertiary care center adopted mandatory vaccination, vaccination rates increased significantly over time.36 The Centers for Medicare & Medicaid Services recently mandated public reporting of vaccination rates in health care workers and residents of long-term care facilities, and compliance is expected to increase as a result.
BETWEEN INFLUENZA OUTBREAKS
Studies show that hygienic measures prevent transmission of respiratory viruses.37 Therefore, the cornerstones of any program to prevent transmission of influenza and other microorganisms in long-term care facilities are hand hygiene, cough and sneeze etiquette, maintaining a distance of 3 feet between beds, and education of residents and health care workers.
