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Volume 26, Number 7—July 2020
Online Report

Evidence Supporting Transmission of Severe Acute Respiratory Syndrome Coronavirus 2 While Presymptomatic or Asymptomatic

Nathan W. FurukawaComments to Author , John T. Brooks, and Jeremy Sobel
Author affiliations: Centers for Disease Control and Prevention, Atlanta, Georgia, USA

Main Article

Table 2

Summary of virologic reports supporting transmission of severe acute respiratory syndrome coronavirus 2 while asymptomatic and presymptomatic*

Reference Setting Patient(s), age/sex Laboratory findings Limitations
Nursing home outbreak in Washington
24 presymptomatic and 3 asymptomatic
Mean RT-PCR Ct value 24.2 for presymptomatic and 27.3 for asymptomatic patients. Viral culture identified infectious virus in 7 (64%) of 11 specimens from presymptomatic patients; no virus detected in 1 asymptomatic patient.
Incomplete viral culture sampling from all presymptomatic and asymptomatic patients.
Repatriated to Germany from Wuhan, China
2 asymptomatic adults
Patients’ RT-PCR Ct values 24 and 30; infectious virus was detected by viral culture for both.
No evidence of transmission during evacuation flight.
Family cluster in Singapore
Asymptomatic 6 mo/M
RT-PCR Ct values 14 at diagnosis and increased to 33 over 9 d.
No evidence of transmission from the infant to another household member.
Cluster in Vietnam related to travel to Wuhan
Asymptomatic 55 y/M
RT-PCR Ct values >40 at diagnosis and during 9 d of viral RNA shedding.
High Ct in the asymptomatic patient suggests minimal infectiousness.
(27) Family cluster in Guangdong, China Asymptomatic, 26 y/M RT-PCR Ct values 22–32 during testing 7–11 d after initial diagnosis. No evidence of transmission to other family members in the cluster.

*Ct, cycle threshold, RT-PCR, reverse transcription PCR.

Main Article

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