Epidemiologic Notes and Reports
Impact of Influenza on a Nursing Home Population -- New York
During December 1982, 49 (60.5%) of 81 residents at a
skilled-nursing facility in upstate New York experienced
influenza-like illness (1) with elevated temperature ( greater than
or
equal to 37.8 C (100.0 F) oral or greater than or equal to 38 C
(100.4 F) rectal) and at least one of the following symptoms:
cough,
congestion, or sore throat. Six of the clinically diagnosed cases
occurred sporadically before December 18, when the main cluster
began,
and the outbreak peaked on December 21 (Figure 1). Influenza type
A(H3N2) virus was grown from three of six respiratory specimens
cultured from ill residents on December 24. Six residents were
hospitalized following influenza-like illnesses. Three of those,
as
well as one non-hospitalized resident with influenza-like illness,
died, for a case-fatality ratio of 8.2%. Sixty-five (80.2%) of the
81
residents were female, and 38 (58.5%) of those were ill. The mean
age
for all patients was 86.4 years.
All residents except one were more than 65 years old, and 78
(96.3%) had at least one pre-existing medical condition for which
influenza vaccine is strongly recommended (2). Influenza vaccine
had
been offered to all residents in October 1982, and permission to
give
it was received for 54 (66.7%), all of whom were vaccinated. Using
the case definition above, the clinical attack rate for the
vaccinated
residents was 48.1%, and for the 27 unvaccinated residents, 85.2%,
resulting in a calculated rate of vaccine efficacy in preventing
clinical influenza illness of 43.5%.
During December, the number of visits for acute respiratory
disease (ARD) at the emergency room (ER) of an adjacent hospital
increased to 171 (31% of total visits) from 64 (14.5% of total
visits)
in November; during the week ending December 12, 33% of ER visits
were
for ARD, compared with 20% or less during each of the preceding 2
weeks, and 10%-15% in early and mid-November.
Reported by R Stricof, MPH, D Morse, MD, R Rothenberg, MD, State
Epidemiologist, New York State Dept of Health; M Johnson, D Weaver,
MD, W Luft, MD, Robert Packer Hospital, Sayre, V Pidcoe, DVM,
Pennsylvania Dept of Health; WHO Collaborating Center for
Influenza,
Influenza Br, Div of Viral Diseases, Center for Infectious
Diseases,
CDC.
Editorial Note
Editorial Note: This outbreak is unusual for its high attack rate
of
influenza-like illness, which ranged from 48% in vaccinated
residents
to 85% in non-vaccinated residents. Although the overall estimated
attack rates are based only on clinical illness, without supportive
diagnostic results for most patients, the probability that the
outbreak was largely associated with influenza viruses is supported
by
the finding that the impact of the outbreak was apparently lessened
by
vaccine use in more than half the residents. To reduce the impact
of
influenza on nursing home residents, it appears desirable that,
except
where specifically contraindicated (e.g., persons with egg
allergy),
consent for vaccination be given by all residents or relatives
responsible for them, and that communications from hospitals or
physicians about increased influenza activity be rapidly made
available to those in the locality responsible for infection
control
measures in nursing homes.
References
CDC. Influenza update--United States. MMWR 1983;32:17.
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