To the Editor:

A small number of cases of coronavirus disease 2019 (Covid-19) have been described in children,1,2 and our understanding of the spectrum of illness is limited.3 We conducted a retrospective analysis involving hospitalized children in Wuhan, China.

From January 7 to January 15, 2020, a total of 366 hospitalized children (≤16 years of age) were enrolled in a retrospective study of respiratory infections at three branches of Tongji Hospital, which are located 14 km to 34 km from one another in central Wuhan (Fig. S1 in the Supplementary Appendix, available with the full text of this letter at NEJM.org). The study was approved by the ethics committee of Tongji Hospital. Among the 366 children, the most frequently detected pathogens were influenza A virus (in 23 patients [6.3%]) and influenza B virus (in 20 [5.5%]). SARS-CoV-2, the virus that causes Covid-19, was detected in 6 patients (1.6%). Informed consent was obtained from the parents or guardians of the patients with Covid-19 for the publication of their clinical data. The dates of illness onset in the six patients with Covid-19 were between January 2 and January 8, 2020, and the patients were hospitalized between January 7 and January 13 (Fig. S2). Details of the study methods are provided in the Supplementary Appendix.

Table 1. Table 1. Summary of the Clinical Characteristics of Six Children with Covid-19.

The median age of the six patients was 3 years (range, 1 to 7) (Table 1). All six children had previously been completely healthy. Common clinical characteristics included high fever (>39°C) (in all six patients), cough (in all six), and vomiting (in four). Laboratory investigations showed that the levels of lymphocytes, white cells, and neutrophils were below the normal range in six, four, and three patients, respectively. Four of the six patients had pneumonia, as assessed radiographically, with computed tomographic scans of the chest showing typical viral pneumonia patterns (Fig. S3). One child was admitted to the pediatric intensive care unit (ICU) and received pooled immune globulin from healthy donors. All the patients were treated empirically with antiviral agents, antibiotic agents, and supportive therapies. All the patients recovered after hospitalization for a median of 7.5 days (range, 5 to 13).

This study showed that Covid-19 occurred in children, causing moderate-to-severe respiratory illness, in the early phase of the SARS-CoV-2 outbreak in Wuhan and was associated with ICU admission in one patient. None of the patients or their family members had had direct exposure to Huanan Seafood Wholesale Market (the initial location to which cases of Covid-19 were linked) or to one another. It is worth mentioning that we unexpectedly found a case of Covid-19 in one patient (Patient 3) who resided outside Wuhan; this patient had illness onset on January 2, 2020. The patient and her family were residents of the Yangxin area of Huangshi and had not traveled outside the city in the month before illness onset. We have not identified the source of infection for this patient. Our findings indicate that SARS-CoV-2 infections in children were occurring early in the epidemic.4

Weiyong Liu, Ph.D.

Tongji Hospital of Huazhong University of Science and Technology, Wuhan, China

Qi Zhang, Ph.D.

Wuhan University, Wuhan, China

Junbo Chen, Ph.D.

Fudan University, Shanghai, China

Rong Xiang, Ph.D.

Central South University, Changsha, China

Huijuan Song, M.Sc.

Sainan Shu, M.D.

Ling Chen, M.D.

Tongji Hospital of Huazhong University of Science and Technology, Wuhan, China

Lu Liang, M.D.

Sichuan University, Chengdu, China

Jiaxin Zhou, M.D.

Lei You, M.Sc.

Fudan University, Shanghai, China

Peng Wu, Ph.D.

University of Hong Kong, Hong Kong, China

Bo Zhang, M.Sc.

Yanjun Lu, Ph.D.

Liming Xia, M.D.

Lu Huang, M.D.

Tongji Hospital of Huazhong University of Science and Technology, Wuhan, China

Yang Yang, Ph.D.

Fang Liu, Ph.D.

Wuhan University, Wuhan, China

Malcolm G. Semple, Ph.D., B.M., B.Ch.

University of Liverpool, Liverpool, United Kingdom

Benjamin J. Cowling, Ph.D.

University of Hong Kong, Hong Kong, China

Ke Lan, M.D., Ph.D.

Wuhan University, Wuhan, China

[email protected]

Ziyong Sun, Ph.D.

Tongji Hospital of Huazhong University of Science and Technology, Wuhan, China

[email protected]

Hongjie Yu, Ph.D.

Fudan University, Shanghai, China

[email protected]

Yingle Liu, Ph.D.

Wuhan University, Wuhan, China

[email protected]

Supported by the Ministry of Science and Technology of China, by a grant (2017ZX10103005) from the National Mega Project on Major Infectious Disease Prevention , and by a grant (2018YFE0204500) from the National Key Research and Development Program of China . Disclosure forms provided by the authors are available with the full text of this letter at NEJM.org.

This letter was published on March 12, 2020, at NEJM.org.

Drs. W. Liu, Q. Zhang, and J. Chen and Drs. K. Lan, Z. Sun, H. Yu, and Y. Liu contributed equally to this letter.