Grand Rounds

How Do Clinical Characteristics of COVID-19 Infection Differ Between Symptomatic and Asymptomatic Patients?

BACKGROUND AND PURPOSE:

Yang et al. (JAMA Netw Open., 2020) describe clinical characteristics of both symptomatic and asymptomatic patients with confirmed SARS-CoV-2 infection

Case series (December 24, 2019, to February 24, 2020)
Setting
- Wuhan, China
Participants
- Consecutive hospitalized cases with lab confirmed COVID-19
- Recruited from 26 cluster cases who had
  - Confirmed history of exposure to the Hunan seafood market or
  - Close contact with another patient who had been hospitalized for COVID-19
Study design
- RT-PCR on nasopharyngeal swabs was performed every 24 to 48 hours
- CT scan: On admission with a second chest CT at 4 to 6 days and third CT at 6 to 7 days after the second scan
  - Additional CT for worsening status
- CD4+T lymphocyte count was tested every 5 to 6 days

78 patients
- Median (IQR) number of patients per cluster: 3 (2-3) patients
- Range: 2 to 10 patients per cluster
Symptomatic vs asymptomatic
- Symptomatic cases: 57.7% of cases (45 patients)
- Asymptomatic: 42.3% of cases (33 patients)
Patients who were asymptomatic tended to
- Be younger (P < 0.001)
  - Asymptomatic: median (IQR) age 37 (26 to 45) years
  - Symptomatic: 56 (34 to 63) years
- Be women (P = 0.002)
  - Asymptomatic: 66.7% were women (22 patients)
  - Symptomatic: 31.0% were women (14 patients)
- Not have biochemical evidence of liver injury (P = 0.03)
  - Asymptomatic: 3% had a liver injury (1 patient)
  - Symptomatic: 20.0% had a liver injury (9 patients)
- Have higher CD4+T lymphocyte counts (P = 0.001)
  - Asymptomatic: median (IQR) 719 (538 to 963) per uL
  - Symptomatic: 474 (354 to 811) per ul
- Have faster lung recovery based on CT scan (P = 0.001)
  - Asymptomatic: median (IQR) duration 9 (6 to 18) days
  - Symptomatic: 15 (11 to 18) days
- Have a shorter duration of viral shedding on nasopharyngeal swabs (P = 0.001)
  - Asymptomatic: median (IQR) duration 8 (3 to 12) days
  - Symptomatic: 19 (16 to 24) days
- Have more stable SARS-CoV-2 testing results
  - Asymptomatic: 12.1% had fluctuated results (4 patients)
  - Symptomatic: 33.3% had fluctuated results (15 patients)

Compared to symptomatic COVID-19 patients, asymptomatic patients experienced less organ injury and CT scans improved more rapidly
- Consumption of CD4 lymphocytes was lower, suggesting less damage to the immune system
Asymptomatic patients appear to have a shorter duration of viral shedding, suggesting that they may be infectious for a shorter period of time

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