CHARACTERISTICS OF CORONAVIRUS DISEASE 2019 IN CHINA were used in a previous study to assess the se-descriptive only.We used ArcGIS.version 10.2.2 verity of other serious infectious diseases,such to plot the numbers of patients with reportedly as H7N9 infection.Secondary end points were the rate of death and the time from symptom em光e 3.6.2 (R Foundation for Statistical Computing) composite end point ReSuLts STUDY DEFINITIONS The incubation period was defined as the inter- DEMOGRAPHIC AND CLINICAL CHARACTERISTICS val between the potential earliest date of contact Of the 7736 patients with Covid-19 who had been of the transmission source (wildlife or person hospitalized at 552 sites as of January 29,2020 ed or confirmed case)and the pote est date of symptoms i.w。ns 132 pital The hosp patients had continuous exposure to contamina. tals that were included in this study accounted tion sources;in these cases,the latest date of for 29.7%of the 1856 designated hospitals exposure was recorded.The summary statistics where patients with Covid-19 could be admitted of incubation periods we e calculated on the in 30 provinces,autonomous regions,or munici- f29 clear information palities across Ch the posure ed of e de phice of37.5℃or higher. e health care and a history of fined as a lymphe ocvte count of less than 1500 contact with wildlife was documented in 1.9% cells per cubic millimeter.Thrombocytopenia was 483 patients (43.9%)were residents of wuhan defined as a platelet coun of less Among the patients who lived outside Wuhan per cubic millimeter.Additional definitions- 2.3%ha conta ct w h residents of Wuhan,in ife,ac ute respirator cluding 3 had vis ute heartm e city nc nd myolysis-are provided in the Supplementary The median incubation period was 4 days Appendix,available at NEJM.org. (interquartile range 2 to 7)The median age of the patients was 47 years(interquartile range,35 LABORATORY CONFIRMATIO to 58);0.9%of the patients were younger than mation of SARS-Co as per 5 years or age.A ota ent in tie 88 The nd m RT-PCR assavs were erformed in accordance was cough (67.8%):nausea or vomiting (5.0%) with the protocol established by the WHO.De-and diarrhea (3.8%)were uncommon.Among tails regarding laboratory confirmation processes the overall population,23.7%had at least one are provided in the Supplementary Appendix. coexisting illness (e.g..hypertension and chronic STATISTICAL ANALYSIS sdiCoid-19 the A of severity in and interquartile ranges or simple ranges,as ap patients and severe in 173 patients.Patients with propriate.Categorical variables were summarized severe disease were older than those with non- as counts and percentages.No imputation was severe disease by a median of 7 years.Moreover made for missing data.Because the cohort of the presence of any coexisting illness was more patients in our s dy wa ed tr ere di se tha dom selection,all stati om ra h nonsevere disease (8.%vs. N ENGLJ MED NEJM.ORG The New England Joumal of Medicine All rights n engl j med nejm.org 3 Char acteristics of Coronavirus Disease 2019 in China were used in a previous study to assess the se￾verity of other serious infectious diseases, such as H7N9 infection.16 Secondary end points were the rate of death and the time from symptom onset until the composite end point and until each component of the composite end point. Study Definitions The incubation period was defined as the inter￾val between the potential earliest date of contact of the transmission source (wildlife or person with suspected or confirmed case) and the poten￾tial earliest date of symptom onset (i.e., cough, fever, fatigue, or myalgia). We excluded incuba￾tion periods of less than 1 day because some patients had continuous exposure to contamina￾tion sources; in these cases, the latest date of exposure was recorded. The summary statistics of incubation periods were calculated on the basis of 291 patients who had clear information regarding the specific date of exposure. Fever was defined as an axillary temperature of 37.5°C or higher. Lymphocytopenia was de￾fined as a lymphocyte count of less than 1500 cells per cubic millimeter. Thrombocytopenia was defined as a platelet count of less than 150,000 per cubic millimeter. Additional definitions — including exposure to wildlife, acute respiratory distress syndrome (ARDS), pneumonia, acute kidney failure, acute heart failure, and rhabdo￾myolysis — are provided in the Supplementary Appendix, available at NEJM.org. Laboratory Confirmation Laboratory confirmation of SARS-CoV-2 was per￾formed at the Chinese Center for Disease Preven￾tion and Control before January 23, 2020, and subsequently in certified tertiary care hospitals. RT-PCR assays were performed in accordance with the protocol established by the WHO.17 De￾tails regarding laboratory confirmation processes are provided in the Supplementary Appendix. Statistical Analysis Continuous variables were expressed as medians and interquartile ranges or simple ranges, as ap￾propriate. Categorical variables were summarized as counts and percentages. No imputation was made for missing data. Because the cohort of patients in our study was not derived from ran￾dom selection, all statistics are deemed to be descriptive only. We used ArcGIS, version 10.2.2, to plot the numbers of patients with reportedly confirmed cases on a map. All the analyses were performed with the use of R software, version 3.6.2 (R Foundation for Statistical Computing). Results Demographic and Clinical Characteristics Of the 7736 patients with Covid-19 who had been hospitalized at 552 sites as of January 29, 2020, we obtained data regarding clinical symptoms and outcomes for 1099 patients (14.2%). The largest number of patients (132) had been ad￾mitted to Wuhan Jinyintan Hospital. The hospi￾tals that were included in this study accounted for 29.7% of the 1856 designated hospitals where patients with Covid-19 could be admitted in 30 provinces, autonomous regions, or munici￾palities across China (Fig. 1). The demographic and clinical characteristics of the patients are shown in Table 1. A total of 3.5% were health care workers, and a history of contact with wildlife was documented in 1.9%; 483 patients (43.9%) were residents of Wuhan. Among the patients who lived outside Wuhan, 72.3% had contact with residents of Wuhan, in￾cluding 31.3% who had visited the city; 25.9% of nonresidents had neither visited the city nor had contact with Wuhan residents. The median incubation period was 4 days (interquartile range, 2 to 7). The median age of the patients was 47 years (interquartile range, 35 to 58); 0.9% of the patients were younger than 15 years of age. A total of 41.9% were female. Fever was present in 43.8% of the patients on admission but developed in 88.7% during hospi￾talization. The second most common symptom was cough (67.8%); nausea or vomiting (5.0%) and diarrhea (3.8%) were uncommon. Among the overall population, 23.7% had at least one coexisting illness (e.g., hypertension and chronic obstructive pulmonary disease). On admission, the degree of severity of Covid-19 was categorized as nonsevere in 926 patients and severe in 173 patients. Patients with severe disease were older than those with non￾severe disease by a median of 7 years. Moreover, the presence of any coexisting illness was more common among patients with severe disease than among those with nonsevere disease (38.7% vs. The New England Journal of Medicine Downloaded from nejm.org at SOUTHERN MEDICAL UNIVERSITY on March 6, 2020. For personal use only. No other uses without permission. Copyright © 2020 Massachusetts Medical Society. All rights reserved