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Volume 26, Number 8—August 2020
Research Letter

Secondary Transmission of Coronavirus Disease from Presymptomatic Persons, China

Weiwei Zhang1, Weibin Cheng1, Lei Luo1, Yu Ma, Conghui Xu, Pengzhe QinComments to Author , and Zhoubin ZhangComments to Author 
Author affiliations: Guangzhou Center for Disease Control and Prevention, Guangzhou, China (W. Zhang, L. Luo, Y. Ma, C. Xu, P. Qin, Z. Zhang); Guangdong Second Provincial General Hospital, Guangzhou (W. Cheng)

Main Article

Table

Characteristics of and secondary attack rates among 369 close contacts of persons with presymptomatic coronavirus disease 2019, China*

Variable
No. contacts
No. infected
Attack rate, % (95% CI)
Relative risk (95% CI)
Sex
M 217 5 2.3 (0.1–5.2) Referent
F
152
7
4.6 (2.2–8.9)
2.1 (0.6–6.6)
Age
≤17 46 2 4.3 (1.2–14.5) Referent
18–30 104 3 2.9 (1.0–8.1) 0.7 (0.1–4.1)
31–40 72 1 1.4 (0.2–7.4) 0.4 (0.03–3.5)
41–50 68 1 1.5 (0.3–7.9) 0.4 (0.03–3.7)
51–60 54 3 5.6 (1.9–15.1) 1.3 (0.2–8.1)
≥61
25
2
8.0 (1.4–27.5)
1.9 (0.3–14.5)
Index case-patient status*
Asymptomatic 119 1 0.8 (0.2–5.6) Referent
Mild symptoms 141 5 3.5 (1.5–8.0) 4.3 (0.5–37.7)
Moderate symptoms 87 5 5.7 (2.5–12.8) 7.2 (0.8–62.7)
Severe symptoms
22
1
4.5 (0.8–21.8)
5.6 (0.3–93.4)
Contact mode
Social interaction with friends or relatives 66 1 1.5 (0.3–8.1) Referent
Lived together 62 10 16.1 (9.0–27.2) 12.5 (1.6–100.8)
Worked together 119 0 0 0
Social interaction with strangers
122
1
0.8 (0.2–4.9)
0.5 (0.03–8.7)
Contact frequency†
Rare 149 1 0.7 (0.1–3.7) Referent
Moderate 159 1 0.6 (0.1–3.5) 0.9 (0.1–15.1)
Frequent
61
10
16.4 (9.2–27.6)
29.0 (3.6–232.3)
*Status as of March 30, 2020, based on the person’s clinical course assessed by a physician. Moderate symptoms included fever, respiratory symptoms, and radiographic evidence of pneumonia. Severe symptoms included breathing rate >30/min; oxygen saturation level <93% at rest; oxygen concentration level PaO2/FiO2 <300 mmHg (1 mmHg = 0.133kPa); lung infiltrates >50% within the past 24–48 h; respiratory failure requiring mechanical ventilation; septic shock; or multiple organ dysfunction or failure. All other symptomatic cases were classified as mild. 
†Rare contact was defined as contacted with index cases <2 times during 2 days preceding confirmation of infection. Moderate contact was defined as contacted with index cases 3–5 times during 2 days preceding confirmation of infection. Frequent contact was defined as contacted with index cases >5 times during 2 days preceding confirmation of infection.

Main Article

1These first authors contributed equally to this article.

Page created: May 15, 2020
Page updated: July 19, 2020
Page reviewed: July 19, 2020
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