J Korean Med Sci.  2020 Aug;35(32):e297. 10.3346/jkms.2020.35.e297.

Clinical Characteristics of COVID-19: Clinical Dynamics of Mild Severe Acute Respiratory Syndrome Coronavirus 2 Infection Detected by Early Active Surveillance

• Suh HJ
• Kim DH
• Heo EY
• Lee HW
• Lee JK
• Lee CS
• Kim M
• Jeon YD
• Chung JW
• Kim YK
• Shin PJ
• Lee MS
• Kang JS
• Lee MJ
• Kim BN
• Park SW

• KMID: 2505585
• DOI: http://doi.org/10.3346/jkms.2020.35.e297

Abstract

Background
There is limited information describing the presenting characteristics and dynamic clinical changes in severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection diagnosed in the early phase of illness. This study is a case series of patients with coronavirus disease 2019 (COVID-19) admitted to 11 hospitals in Korea.
Methods
Patients with confirmed SARS-CoV-2 infection by positive polymerase chain reaction (PCR) testing of respiratory specimens by active surveillance that were finally discharged between February 20 and April 30, 2020 were included. Patients were classified into mild and non-mild groups on initial admission according to oxygen demand and Sequential Organ Failure Assessment score, and the mild group was followed up and subgrouped into non-aggravation and aggravation groups.
Results
A total of 161 patients with SARS-CoV2 infection were enrolled. Among the mild group of 136 patients, 11.7% of patients experienced clinical aggravation during hospitalization, but there was no initial clinical parameter on admission predicting their aggravation. Fever (odds ratio [OR], 4.56), thrombocytopenia (OR, 12.87), fever (OR, 27.22) and lactate dehydrogenase (LDH) > 300 U/L (OR, 18.35), and CRP > 1 mg/dL (OR, 11.31) significantly indicated aggravation in the 1st, 2nd, 3rd, and 4th 5-day periods, respectively. PCR positivity lasted for a median of 22 days and 32 days after the onset of illness in the nonaggravation and aggravation groups, respectively.
Conclusion
Old age was associated with early severe presentation. Clinical aggravation among asymptomatic or mild patients could not be predicted initially but was heralded by fever and several laboratory markers during the clinical course.

Keyword

COVID-19; SARS-CoV-2; Korea; Mild; Active Surveillance

Figure

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  Fig. 1 Study design. A total of 161 patients were enrolled, with 136 patients in the mild group and 25 patients in the non-mild group. The mild group was subgrouped into the non-aggravation group of 120 patients and the aggravation group of 16 patients during hospitalization.SARS-CoV-2 = severe acute respiratory syndrome coronavirus 2, SOFA = Sequential Organ Failure Assessment.

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  Fig. 2 Severity of patients based on oxygen requirement and SOFA score at baseline and during clinical course. In the initial mild group, a new need for oxygen therapy occurred in 7 patients (4 of low-flow, 1 of high-flow and 2 of mechanical ventilator) during the clinical course.SOFA = Sequential Organ Failure Assessment.

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  Fig. 3 Timeline after onset of illness of the initial mild group on admission. (A) Overall clinical course of the mild group. New respiratory symptoms, fever (> 37.5°C) and new oxygen demand occurred at median 5, 6 and 10 days after onset of illness, and the prevalence were 72.8%, 43.4% and 5.1%, respectively. (B) Dynamic changes in respiratory symptoms, fever and oxygen demand in the non-aggravation and aggravation groups. In the aggravation group, the parameters were mostly resolved after 3 weeks of illness onset, and they were related to a longer period of polymerase chain reaction positivity.RT-PCR = reverse transcription polymerase chain reaction.

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  Fig. 4 Dynamic changes in laboratory parameters. There were significant differences between the two groups in lymphocytes, platelets, total bilirubin and CRP on the 6–10th day of illness and LDH on the 11–15th day of illness.WBC = white blood cell, LDH = lactate dehydrogenase, CRP = C-reactive protein.

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  Fig. 5 Dynamic changes in rRT-PCR positivity for upper and lower respiratory specimens. (A) The cumulative positivity of rRT-PCR testing between the two groups. The cumulative positivity of rRT-PCR testing at days 7, 14, 21 and 28 after onset of illness was 98.3%, 81.7%, 54.2% and 23.3% in the non-aggravation group, respectively, and 100%, 100%, 87.5% and 68.7% in the aggravation groups, respectively. (B) The distribution of Ct values between the two groups. The mean Ct values surpassed 35 after 20 days of illness onset and remained at similar levels thereafter.rRT-PCR = real-time reverse transcription polymerase chain reaction, Ct = cycle threshold.

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