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).
Wash your hands!
Hands should be washed before and after direct contact with patients or with inanimate objects in their immediate vicinity.38 Contrary to popular belief, hands should also be washed before and after wearing gloves, particularly when handling an invasive device for patient care, and after contact with bodily fluids, excretions, mucous membranes, non-intact skin, or wound dressings. Hands should be washed not only between patients but also during care for the same patient if moving from a contaminated body site to a clean site.
Hands should be washed for 15 to 20 seconds using soap and water or an alcohol-based foam or gel; when hands are visibly soiled, only soap and water should be used. It is not known whether adding virucidals or antiseptics to normal hand-washing further decreases the spread of these viruses.
Continuous education, feedback interventions, and patient-awareness programs can improve hand-washing compliance, but they are not sufficient. Easily accessible dispensers for alcohol-based waterless antiseptic foam or gel can significantly improve hand hygiene rates among health care workers.39
DETECTING INFLUENZA OUTBREAKS
Direct fluorescent antigen detection and nucleic acid detection by polymerase chain reaction (PCR) are the tests recommended for early detection of influenza outbreaks in long-term care facilities. Rapid point-of-care tests to detect influenza antigen are only 60% to 70% sensitive,13,40 viral culture takes several days, and serologic diagnosis requires documentation of seroconversion at least 2 weeks apart, and so none of these is adequate for the early detection of an influenza outbreak.
There is no widely available test to differentiate influenza A/H1N1 from A/H3N2, or to test for drug resistance. In addition, the PCR tests widely used today do not differentiate between seasonal influenza A/H1N1 and the new, pandemic influenza A/H1N1 variant. Efforts are under way to produce and distribute such a test.
Controlling influenza outbreaks
An outbreak should be declared when two or more residents develop an influenza-like illness within 72 hours of each other during the influenza season.41 After influenza infection is confirmed by laboratory testing, testing of all residents who subsequently develop an influenza-like illness may not be feasible, and other respiratory viruses may be responsible for mixed outbreaks during influenza epidemics, particularly respiratory syncytial virus.
Roommates of residents who test positive for influenza have a risk of acquiring influenza three times higher than that of residents living in single rooms.42 Obviously, private rooms for all residents would be optimal, but this is not practical in most facilities. “Cohorting” (ie, housing infected residents together) is reasonable, but in this situation they might infect each other with other viruses or with influenza viruses of different serotypes.
When an outbreak occurs, potential solutions include closing subunits of the facility to new admissions, limiting movement of residents and health care workers from affected to unaffected units, and using curtains or other barriers between roommates. But most important during seasonal outbreaks are hand hygiene, proper cough and sneeze etiquette, and 3-foot separation between roommates. A simulation model showed that during an influenza pandemic, preventing ill residents of long-term care facilities from making contact with other residents may reduce rates of illness and death by about 60%.43 If a long-term care facility resident is visibly coughing and cannot cover his or her mouth, health care workers should wear a mask when within 3 feet of the patient or when entering the room of a resident with confirmed influenza.
CHEMOPROPHYLAXIS DURING INFLUENZA OUTBREAKS
When influenza outbreaks are recognized early in long-term care facilities, appropriate infection control measures and chemoprophylaxis can be started. Chemoprophylaxis should also be considered in residents in whom influenza vaccination is contraindicated, such as those with severe egg allergy.
Rimantadine is preferred over amantadine in residents of long-term care facilities, since amantadine is associated with a much higher rate of adverse events (18.6% vs 1.9%), especially confusion (10.6% vs 0.6%), resulting in more frequent discontinuation (17.3% vs 1.9%).44 In addition, viral resistance to amantadine develops in about 30% of those who receive it. In long-term care facilities, viral resistance occurs not only when it is used for the management of influenza, but also when it is used to treat Parkinson disease.45
Oseltamivir prophylaxis for 6 weeks in influenza-vaccinated, frail elderly residents of long-term care facilities during influenza epidemics was 91% effective in preventing laboratory-confirmed clinical influenza, and 85% effective in preventing a secondary bacterial complication such as pneumonia or sinusitis.46 The rate of adverse events associated with oseltamivir in that population was similar to that with placebo. Importantly, oseltamivir was not associated with suppression of antibody response to influenza infection or vaccination.
Oseltamivir is very effective in terminating influenza outbreaks in long-term care facilities, even when amantadine fails.4,13 When used in that manner, it is also associated with decreased antibiotic prescriptions, hospitalizations, deaths,47 and substantial cost-savings, even when compared with amantadine, which has a much lower acquisition cost but a higher rate of adverse events, lower efficacy, and individualized dosing requirements.48
Zanamivir prophylaxis for 2 weeks given to unvaccinated residents was 29% effective in preventing all symptomatic influenza confirmed by laboratory testing (by culture, PCR, or seroconversion). It was 65% effective in preventing symptomatic culture-confirmed influenza, 70% effective in preventing febrile, laboratory-confirmed influenza, and 21% effective in preventing complications.49 It was well tolerated in this population and was not associated with the emergence of zanamivir resistance. Zanamivir also provides 61% additional protective efficacy over rimantadine in vaccinated residents of long-term care facilities,50 primarily because of the emergence of viruses resistant to rimantadine. However, up to 50% of elderly people may have difficulty loading and priming the Diskhaler device used to deliver zanamivir.51
While several studies have shown chemoprophylaxis to be effective, it is not possible to ascribe the decrease in cases during an outbreak entirely to antiviral drugs since most studies were not placebo-controlled, and since the natural tendency of outbreaks is to subside.
