RAND STUDY FINDS VACCINATION OF NURSING HOME STAFF, RESIDENTS, KEY
TO REDUCING INFLUENZA OUTBREAKS
Potentially deadly influenza outbreaks in nursing homes are less likely to occur when large
numbers of staff and residents get flu shots, according to a study issued today by the RAND
Corporation.
The study by the nonprofit research organization found that nursing homes were 60 percent less
likely to have a cluster of influenza-like illness cases if more than 55 percent of the staff and more
than 89 percent of the residents were vaccinated for influenza. Researchers defined clusters of
influenza-like illness as more than three cases with influenza-like symptoms reported within 72
hours in close proximity within the nursing home.
"Simply immunizing nursing home residents against influenza is not going to ensure they're
protected from getting the flu," said Lisa R.Shugarman, a RAND researcher and lead author of
the study. "It's only the combination of high rates of immunization for residents and staff
that appears to make the difference."
The RAND Health study - titled "The Influence of Staff and Resident Immunization Rates on
Influenza-like Illness Outbreaks in Nursing Homes" - appears in the Nov. 15 issue of the Journal
of the American Medical Directors Association.
Influenza outbreaks in nursing homes are common and can result in prolonged hospitalizations
and death for vulnerable elderly residents, particularly those with serious chronic health
problems. From 1979 to 2000, influenza hospitalization rates for elderly patients were 17 times
higher than the average rate, and more than 90 percent of the patients who died were elderly.
According to another study, nursing home residents age 65 and older were three times more likely
to be hospitalized for influenza than people of similar ages who did not live in nursing homes.
The influenza vaccine can be 86 percent effective for healthy adults when the vaccine matches
the prevailing influenza strain. However, studies have shown that the vaccine is less effective
among the elderly. In nursing homes, it's estimated to be only 23 percent effective against
influenza-like illnesses for residents, and not significantly effective against influenza.
"Elderly people's immune systems are simply not as strong as younger adults' and the elderly
often have multiple chronic conditions that make the immune system less capable of fighting off
other diseases," Shugarman said.
In fact, Shugarman and her colleagues were unable to validate that immunization rates of
residents had any impact on rates of influenza-like illnesses or hospitalizations in their study. Nor
were staff vaccination rates on their own a significant predictor. Only if both staff and resident
immunization rates were high did the likelihood of influenza-like illness cases and
hospitalizations decrease.
Researchers surveyed more than 340 nursing homes belonging to a single nursing home
corporation with facilities located across the United States. Ninety percent responded, for a final
sample size of 301 nursing homes. The facilities ranged in size from 34 beds to 355. Vaccination
status was self-reported and not verified by medical abstraction or review of records at the
nursing homes.
Only a third of the facilities tested patients for influenza after they developed influenza-like
symptoms.
"Many nursing homes find it impractical to test residents because the tests are expensive, and the
results typically would not alter the course of medical treatment," Shugarman said.
As a result, researchers asked how many residents were diagnosed with influenza-like symptoms.
These consist of a sudden onset of fever or complaints of feverishness, and at least one
respiratory symptom such as sore throat, runny nose, cough or nasal congestion.
The survey focused on influenza-like illness clusters during the October 2004 to May 2005
influenza season, which was distinguished by the fact that the most common strain of the virus
was not covered by the vaccine given that season. The average immunization rate was 78.4
percent for residents, and 40.8 percent for staff. More than a third of the nursing homes -102 of
301 - reported an influenza-like illness cluster. Of those that did, the average cluster was more
than 15 residents and the average number of hospitalizations was 2.2, with an average of less than
1 death per facility. Researchers also found that nursing homes with no influenza-like illness
clusters were more likely to have large numbers of Medicaid-eligible patients, an unusual finding
that warrants further study, Shugarman said.
There is increasing support in the medical community for encouraging health care workers to be
vaccinated against influenza, including recommendations from the Joint Commission on
Accreditation of Healthcare Organizations. But if future studies confirm the results of this one,
Shugarman said more forceful requirements may be needed. Educating staff to be sure they know
the problems that outbreaks can cause or providing some incentives to get immunized may be
useful strategies. Publishing a nursing home's staff immunization rates so that residents' family
members can compare facilities also might be a way of increasing vaccination rates for staff.
The study also has implications for healthy adults who want to stay well and for public health
efforts to limit the severity of influenza outbreaks, which can put additional strain on an already
overburdened health care system.
"Low-cost public health measures such as hand-washing and social distancing - measures that
decrease the frequency of close contact with other people, particularly those known to be sick- are
just as valid as they ever were," Shugarman said. "People should not be lulled into a false sense of
security by getting a flu shot."
Other authors of the study include Craig Hales and Barbara Bardenheier, with the U.S. Centers
for Disease Control and Prevention; RAND researcher Claude Messan Setodji; and former
RAND scientist Joanne Lynn. The study was funded in part by the U.S. Centers for Disease
Control and Prevention.
RAND Health is the nation's largest independent health policy research program, with a broad
research portfolio that focuses on health care quality, costs and delivery, among other topics.