Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility | NEJM

Abstract

Background

Severe
acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection can
spread rapidly within skilled nursing facilities. After identification
of a case of Covid-19 in a skilled nursing facility, we assessed
transmission and evaluated the adequacy of symptom-based screening to
identify infections in residents.

Methods

We
conducted two serial point-prevalence surveys, 1 week apart, in which
assenting residents of the facility underwent nasopharyngeal and
oropharyngeal testing for SARS-CoV-2, including real-time
reverse-transcriptase polymerase chain reaction (rRT-PCR), viral
culture, and sequencing. Symptoms that had been present during the
preceding 14 days were recorded. Asymptomatic residents who tested
positive were reassessed 7 days later. Residents with SARS-CoV-2
infection were categorized as symptomatic with typical symptoms (fever,
cough, or shortness of breath), symptomatic with only atypical symptoms,
presymptomatic, or asymptomatic.

Results

Twenty-three
days after the first positive test result in a resident at this skilled
nursing facility, 57 of 89 residents (64%) tested positive for
SARS-CoV-2. Among 76 residents who participated in point-prevalence
surveys, 48 (63%) tested positive. Of these 48 residents, 27 (56%) were
asymptomatic at the time of testing; 24 subsequently developed symptoms
(median time to onset, 4 days). Samples from these 24 presymptomatic
residents had a median rRT-PCR cycle threshold value of 23.1, and viable
virus was recovered from 17 residents. As of April 3, of the 57
residents with SARS-CoV-2 infection, 11 had been hospitalized (3 in the
intensive care unit) and 15 had died (mortality, 26%). Of the 34
residents whose specimens were sequenced, 27 (79%) had sequences that
fit into two clusters with a difference of one nucleotide.

Conclusions

Rapid
and widespread transmission of SARS-CoV-2 was demonstrated in this
skilled nursing facility. More than half of residents with positive test
results were asymptomatic at the time of testing and most likely
contributed to transmission. Infection-control strategies focused solely
on symptomatic residents were not sufficient to prevent transmission
after SARS-CoV-2 introduction into this facility.

Presymptomatic SARS-CoV-2 Infections and Transmission in a Skilled Nursing Facility | NEJM

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