The NEW ENGLAND JOURNAL Of MEDICINE Linked to Huanan market Not linked to Huanan market A novel coro CR diagnostic reagents provided to Wuhan by China CDC 45 WHC Huaeo irst con eported in anothe R8crS provinces 10- 5811141720 Nov. Dec n 2019 Outbreak Period 2020 The declir after sis and lat ssion and wHo World Health orea cifically,the latter part of the curve doe first period was for ain nt a Seafood wholesale Marke the cutoff date.Care should be taken in inter- second period was for those with onset betweer preting the speed of growth in cases in January,January 1 and January 11,which was the date given an increase in the availability and use of when RT-PCR reagents were provided to Wuhan testing kits as time has progressed.The major- and the third period was tho e with illness onse ity c est cases m 0 or al r January 12 (Tab 1).The patient bure to he in e were number of nonlinked cases beginning in late ure to the Huanan Seafood December Market The pro portion of cases in health care The median age of the patients was 59 years workers gradually increased across the three (range,15 to 89),and 240 of the 425 patients periods (Table 1). (56%)were male .Ther e were no case in chil We examined data on exposures w ye we the days(9%conf N ENGLJ MED NEJM.ORC The New Eng Downloaded from ejm.ga SOUTHERN ME land Joural of Medicine s Mo 4 n engl j med nejm.org The new england journal o f medicine cifically, the latter part of the curve does not indicate a decrease in the number of incident cases but is due to delayed case ascertainment at the cutoff date. Care should be taken in inter￾preting the speed of growth in cases in January, given an increase in the availability and use of testing kits as time has progressed. The major￾ity of the earliest cases included reported expo￾sure to the Huanan Seafood Wholesale Market, but there was an exponential increase in the number of nonlinked cases beginning in late December. The median age of the patients was 59 years (range, 15 to 89), and 240 of the 425 patients (56%) were male. There were no cases in chil￾dren below 15 years of age. We examined char￾acteristics of cases in three time periods: the first period was for patients with illness onset before January 1, which was the date the Huan￾an Seafood Wholesale Market was closed; the second period was for those with onset between January 1 and January 11, which was the date when RT-PCR reagents were provided to Wuhan; and the third period was those with illness onset on or after January 12 (Table 1). The patients with earlier onset were slightly younger, more likely to be male, and much more likely to report exposure to the Huanan Seafood Wholesale Market. The proportion of cases in health care workers gradually increased across the three periods (Table 1). We examined data on exposures among 10 confirmed cases, and we estimated the mean incubation period to be 5.2 days (95% confidence Figure 1. Onset of Illness among the First 425 Confirmed Cases of Novel Coronavirus (2019-nCoV)–Infected Pneumonia (NCIP) in Wuhan, China. The decline in incidence after January 8 is likely to be due to delays in diagnosis and laboratory confirmation. China CDC denotes Chi￾nese Center for Disease Control and Prevention, NHC National Health Commission of the People’s Republic of China, PCR polymerase chain reaction, WHC Wuhan Health Commission, and WHO World Health Organization. No. of Cases 45 50 35 40 30 25 15 10 20 5 0 27 30 3 6 9 12 15 18 21 24 27 30 2 5 8 11 14 17 20 Nov. 2019 Dec. 2020 Jan. A novel coronavirus was officially announced as the causative pathogen of the outbreak by China CDC Huanan Seafood Wholesale Market closed Outbreak announced by WHC; NHC and China CDC involved in investigation and response Case-finding activated Pneumonia cases linked to the Huanan Seafood Wholesale Market China CDC publicly shared the gene sequence of the novel coronavirus; completed PCR diagnostic reagent development and testing PCR diagnostic reagents provided to Wuhan First confirmed case from Wuhan reported outside China (in Thailand) China CDC emergency response level upgraded to Level 1 (the highest level); national technical protocols for 2019- nCoV released by NHC NCIP incorporated as a notifiable disease in the Infectious Disease Law and Health and Quarantine Law in China Reagent probes and primers shared with the public by China CDC Strict exit screening measures activated in Wuhan, people with body temperature ≥37.3ºC were restricted from leaving First confirmed case reported in another province in China (in a person who had traveled from Wuhan); China CDC issued test reagent to all provinces in China China CDC Level 2 emergency response activated Emergency monitoring, case investigation, close contact management, and market investigation initiated, technical protocols for Wuhan released; NHC notified WHO and relevant countries and regions; gene sequencing completed by China CDC Outbreak Period Linked to Huanan market Not linked to Huanan market The New England Journal of Medicine Downloaded from nejm.org at SOUTHERN MEDICAL UNIVERSITY on March 6, 2020. 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