Older adults are susceptible to severe coronavirus disease 2019 (COVID-19) outcomes
as a consequence of their age and, in some cases, underlying health conditions (
). A COVID-19 outbreak in a long-term care skilled nursing facility (SNF) in King
County, Washington that was first identified on February 28, 2020, highlighted the
potential for rapid spread among residents of these types of facilities (
). On March 1, a health care provider at a second long-term care skilled nursing facility
(facility A) in King County, Washington, had a positive test result for SARS-CoV-2,
the novel coronavirus that causes COVID-19, after working while symptomatic on February
26 and 28. By March 6, seven residents of this second facility were symptomatic and
had positive test results for SARS-CoV-2. On March 13, CDC performed symptom assessments
and SARS-CoV-2 testing for 76 (93%) of the 82 facility A residents to evaluate the
utility of symptom screening for identification of COVID-19 in SNF residents. Residents
were categorized as asymptomatic or symptomatic at the time of testing, based on the
absence or presence of fever, cough, shortness of breath, or other symptoms on the
day of testing or during the preceding 14 days. Among 23 (30%) residents with positive
test results, 10 (43%) had symptoms on the date of testing, and 13 (57%) were asymptomatic.
Seven days after testing, 10 of these 13 previously asymptomatic residents had developed
symptoms and were recategorized as presymptomatic at the time of testing. The reverse
transcription–polymerase chain reaction (RT-PCR) testing cycle threshold (Ct) values
indicated large quantities of viral RNA in asymptomatic, presymptomatic, and symptomatic
residents, suggesting the potential for transmission regardless of symptoms. Symptom-based
screening in SNFs could fail to identify approximately half of residents with COVID-19.
Long-term care facilities should take proactive steps to prevent introduction of SARS-CoV-2
). Once a confirmed case is identified in an SNF, all residents should be placed on
isolation precautions if possible (
), with considerations for extended use or reuse of personal protective equipment
(PPE) as needed (
Immediately upon identification of the index case in facility A on March 1, nursing
and administrative leadership instituted visitor restrictions, twice-daily assessments
of COVID-19 signs and symptoms among residents, and fever screening of all health
care personnel at the start of each shift. On March 6, Public Health – Seattle and
King County, in collaboration with CDC, recommended infection prevention and control
measures, including isolation of all symptomatic residents and use of gowns, gloves,
eye protection, facemasks, and hand hygiene for health care personnel entering symptomatic
residents’ rooms. A data collection tool was developed to ascertain symptom status
and underlying medical conditions for all residents.
On March 13, the symptom assessment tool was completed by facility A’s nursing staff
members by reviewing screening records of residents for the preceding 14 days and
by clinician interview of residents at the time of specimen collection. For residents
with significant cognitive impairment, symptoms were obtained solely from screening
records. A follow-up symptom assessment was completed 7 days later by nursing staff
members. Nasopharyngeal swabs were obtained from all 76 residents who agreed to testing
and were present in the facility at the time; oropharyngeal swabs were also collected
from most residents, depending upon their cooperation. The Washington State Public
Health Laboratory performed one-step real-time RT-PCR assay on all specimens using
the SARS-CoV-2 CDC assay protocol, which determines the presence of the virus through
identification of two genetic markers, the N1 and N2 nucleocapsid protein gene regions
). The Ct, the cycle number during RT-PCR testing when detection of viral amplicons
occurs, is inversely correlated with the amount of RNA present; a Ct value <40 cycles
denotes a positive result for SARS-CoV-2, with a lower value indicating a larger amount
of viral RNA.
Residents were assessed for stable chronic symptoms (e.g., chronic, unchanged cough)
as well as typical and atypical signs and symptoms of COVID-19. Typical COVID-19 signs
and symptoms include fever, cough, and shortness of breath (
); potential atypical symptoms assessed included sore throat, chills, increased confusion,
rhinorrhea or nasal congestion, myalgia, dizziness, malaise, headache, nausea, and
diarrhea. Residents were categorized as asymptomatic (no symptoms or only stable chronic
symptoms) or symptomatic (at least one new or worsened typical or atypical symptom
of COVID-19) on the day of testing or during the preceding 14 days. Residents with
positive test results and were asymptomatic at time of testing were reevaluated 1
week later to ascertain whether any symptoms had developed in the interim. Those who
developed new symptoms were recategorized as presymptomatic. Ct values were compared
for the recategorized symptom groups using one-way analysis of variance (ANOVA) for
all residents with positive test results for SARS-CoV-2. Analyses were conducted using
SAS statistical software (version 9.4; SAS Institute).
On March 13, among the 82 residents in facility A; 76 (92.7%) underwent symptom assessment
and testing; three (3.7%) refused testing, two (2.4%) who had COVID-19 symptoms were
transferred to a hospital before testing, and one (1.2%) was unavailable. Among the
76 tested residents, 23 (30.3%) had positive test results.
Demographic characteristics were similar among the 53 (69.7%) residents with negative
test results and the 23 (30.3%) with positive test results (Table 1). Among the 23
residents with positive test results, 10 (43.5%) were symptomatic, and 13 (56.5%)
were asymptomatic. Eight symptomatic residents had typical COVID-19 symptoms, and
two had only atypical symptoms; the most common atypical symptoms reported were malaise
(four residents) and nausea (three). Thirteen (24.5%) residents who had negative test
results also reported typical and atypical COVID-19 symptoms during the 14 days preceding
Demographics and reported symptoms for residents of a long-term care skilled nursing
facility at time of testing* (N = 76), by SARS-CoV-2 test results — facility A, King
County, Washington, March 2020
Initial SARS-CoV-2 test results
Negative, no. (%)
Positive, no. (%)
Age, mean (SD)
Long-term admission type to facility A
Length of stay in facility A before test date, days, median (IQR)
Symptoms in last 14 days
At least one typical COVID-19 symptom§
Only atypical COVID-19 symptoms¶
Only stable, chronic symptoms
Specific signs and symptoms reported as new or worse in last 14 days
Shortness of breath
Any preexisting medical condition listed
Chronic lung disease
Abbreviations: COVID-19 = coronavirus disease 2019; IQR = interquartile range, SD = standard
* Testing performed on March 13, 2020.
† Unknown for one resident with negative test results.
§ Typical symptoms include fever, cough, and shortness of breath.
¶ Atypical symptoms include chills, malaise, sore throat, increased confusion, rhinorrhea
or nasal congestion, myalgia, dizziness, headache, nausea, and diarrhea.
** Residents might have multiple conditions.
One week after testing, the 13 residents who had positive test results and were asymptomatic
on the date of testing were reassessed; 10 had developed symptoms and were recategorized
as presymptomatic at the time of testing (Table 2). The most common signs and symptoms
that developed were fever (eight residents), malaise (six), and cough (five). The
mean interval from testing to symptom onset in the presymptomatic residents was 3
days. Three residents with positive test results remained asymptomatic.
Follow-up symptom assessment 1 week after testing for SARS-CoV-2 among 13 residents
of a long-term care skilled nursing facility who were asymptomatic on March 13, 2020
(date of testing) and had positive test results — facility A, King County, Washington,
Symptom status 1 week after testing
Developed new symptoms
Shortness of breath
Real-time RT-PCR Ct values for both genetic markers among residents with positive
test results for SARS-CoV-2 ranged from 18.6 to 29.2 (symptomatic [typical symptoms]),
24.3 to 26.3 (symptomatic [atypical symptoms only]), 15.3 to 37.9 (presymptomatic),
and 21.9 to 31.0 (asymptomatic) (Figure). There were no significant differences between
the mean Ct values in the four symptom status groups (p = 0.3).
Cycle threshold (Ct) values* for residents of a long-term care skilled nursing facility
with positive test results for SARS-CoV-2 by real-time reverse transcription–polymerase
chain reaction on March 13, 2020 (n = 23), by symptom status†,§ at time of test —
facility A, King County, Washington
* Ct values are the number of cycles needed for detection of each genetic marker identified
by real-time reverse transcription–polymerase chain reaction testing. A lower Ct value
indicates a higher amount of viral RNA. Paired values for each resident are depicted
using a different shape. Each resident has two Ct values for the two genetic markers
(N1 and N2 nucleocapsid protein gene regions).
† Typical symptoms include fever, cough, and shortness of breath.
§ Atypical symptoms include chills, malaise, sore throat, increased confusion, rhinorrhea
or nasal congestion, myalgia, dizziness, headache, nausea, and diarrhea.
The figure is a scatter plot showing the cycle threshold values for residents of a
long-term care skilled nursing facility with positive test results for SARS-CoV-2
by real-time reverse transcription–polymerase chain reaction on March 13, 2020 (n
= 23), by symptom status at time of test, in facility A, King County, Washington.
Sixteen days after introduction of SARS-CoV-2 into facility A, facility-wide testing
identified a 30.3% prevalence of infection among residents, indicating very rapid
spread, despite early adoption of infection prevention and control measures. Approximately
half of all residents with positive test results did not have any symptoms at the
time of testing, suggesting that transmission from asymptomatic and presymptomatic
residents, who were not recognized as having SARS-CoV-2 infection and therefore not
isolated, might have contributed to further spread. Similarly, studies have shown
that influenza in the elderly, including those living in SNFs, often manifests as
few or atypical symptoms, delaying diagnosis and contributing to transmission (
). These findings have important implications for infection control. Current interventions
for preventing SARS-CoV-2 transmission primarily rely on presence of signs and symptoms
to identify and isolate residents or patients who might have COVID-19. If asymptomatic
or presymptomatic residents play an important role in transmission in this population
at high risk, additional prevention measures merit consideration, including using
testing to guide cohorting strategies or using transmission-based precautions for
all residents of a facility after introduction of SARS-CoV-2. Limitations in availability
of tests might necessitate taking the latter approach at this time.
Although these findings do not quantify the relative contributions of asymptomatic
or presymptomatic residents to SARS-CoV-2 transmission in facility A, they suggest
that these residents have the potential for substantial viral shedding. Low Ct values,
which indicate large quantities of viral RNA, were identified for most of these residents,
and there was no statistically significant difference in distribution of Ct values
among the symptom status groups. Similar Ct values were reported in asymptomatic adults
in China who were known to transmit SARS-CoV-2 (
). Studies to determine the presence of viable virus from these specimens are currently
SNFs have additional infection prevention and control challenges compared with those
of assisted living or independent living long-term care facilities. For example, SNF
residents might be in shared rooms rather than individual apartments, and there is
often prolonged and close contact between residents and health care providers related
to the residents’ medical conditions and cognitive function. The index patient in
this outbreak was a health care provider, which might have contributed to rapid spread
in the facility. In addition, health care personnel in all types of long-term care
facilities might have limited experience with proper use of PPE. Symptom ascertainment
and room isolation can be exceptionally challenging in elderly residents with neurologic
conditions, including dementia. In addition, symptoms of COVID-19 are common and might
have multiple etiologies in this population; 24.5% of facility A residents with negative
test results for SARS-CoV-2 reported typical or atypical symptoms.
The findings in this report are subject to at least two limitations. First, accurate
symptom ascertainment in persons with cognitive impairment and other disabilities
is challenging; however, this limitation is estimated to be representative of symptom
data collected in most SNFs, and thus, these findings might be generalizable. Second,
because this analysis was conducted among residents of an SNF, it is not known whether
findings apply to the general population, including younger persons, those without
underlying medical conditions, or similarly aged populations in the general community.
This analysis suggests that symptom screening could initially fail to identify approximately
one half of SNF residents with SARS-CoV-2 infection. Unrecognized asymptomatic and
presymptomatic infections might contribute to transmission in these settings. During
the current COVID-19 pandemic, SNFs and all long-term care facilities should take
proactive steps to prevent introduction of SARS-CoV-2, including restricting visitors
except in compassionate care situations, restricting nonessential personnel from entering
the building, asking staff members to monitor themselves for fever and other symptoms,
screening all staff members at the beginning of their shift for fever and other symptoms,
and supporting staff member sick leave, including for those with mild symptoms (
). Once a facility has a case of COVID-19, broad strategies should be implemented
to prevent transmission, including restriction of resident-to-resident interactions,
universal use of facemasks for all health care personnel while in the facility, and
if possible, use of CDC-recommended PPE for the care of all residents (i.e., gown,
gloves, eye protection, N95 respirator, or, if not available, a face mask) (
). In settings where PPE supplies are limited, strategies for extended PPE use and
limited reuse should be employed (
). As testing availability improves, consideration might be given to test-based strategies
for identifying residents with SARS-CoV-2 infection for the purpose of cohorting,
either in designated units within a facility or in a separate facility designated
for residents with COVID-19. During the COVID-19 pandemic, collaborative efforts are
crucial to protecting the most vulnerable populations.
What is already known about this topic?
Once SARS-CoV-2 is introduced in a long-term care skilled nursing facility (SNF),
rapid transmission can occur.
What is added by this report?
Following identification of a case of coronavirus disease 2019 (COVID-19) in a health
care worker, 76 of 82 residents of an SNF were tested for SARS-CoV-2; 23 (30.3%) had
positive test results, approximately half of whom were asymptomatic or presymptomatic
on the day of testing.
What are the implications for public health practice?
Symptom-based screening of SNF residents might fail to identify all SARS-CoV-2 infections.
Asymptomatic and presymptomatic SNF residents might contribute to SARS-CoV-2 transmission.
Once a facility has confirmed a COVID-19 case, all residents should be cared for using
CDC-recommended personal protective equipment (PPE), with considerations for extended
use or reuse of PPE as needed.