EARLY TRANSMISSION DYNAMICS OF NCIP Cluster 1 (December 2019) Cluster 5 ganuary 2020) eaw卫 cw中 case12F575 cas0s2.2s回 case13F319 ce53.Ms,工 Cluster2 (December 2019-January 2020) ases4.6☐ ce21卫 Case22.M64 aomhs Cluster3(December 201) ce1,8工 cae2r国工 13 ae3.M8四D 43 caeAwso0D cae卫 cae42wsID nd other cases case43.2s4□ Figure 3.Detailed Exposures and Dates ofness Onset in Five Clusters Including 16Cases. he first four usters were identified in Wuhan,and the fifth custer was would account for underrepresentation in the tion were much longer,with 89%of patients not wave of epidemic wot dicates the difficult y in identif alt larify this question ad the on has not he It ma cases an ea high as during the SARS and MERS outbreaks.able resources to testing in outpatient clinics One of the features of SARS and MERS out-and emergency departments for proactive case breaks is heterogeneity in transmissibility,and finding,both as part of the containment strategy in particular the rence of super-spreading in locations wi hout local spread yet as well as to permit earlier clinical manage de super-spreac ent of cases. an appro. ecomea feature as the epidemic delays betwen the of Our preliminary estimate of the incubation and seeking medical attention were generally period distribution provides important evidence short,with 27%of patients seeking attention to support a 14-day medical observation period within 2 days after onset,delays to hospitaliza-or quarantine for exposed persons.Our estimate N ENGLIMED NEIM.ORO nal us Copyngnt 2020 Masn engl j med nejm.org 7 Early Transmission Dynamics of NCIP would account for underrepresentation in the confirmed case count. Serosurveys after the first wave of the epidemic would clarify this question. Although infections in health care workers have been detected, the proportion has not been as high as during the SARS and MERS outbreaks.15 One of the features of SARS and MERS out￾breaks is heterogeneity in transmissibility, and in particular the occurrence of super-spreading events, particularly in hospitals.16 Super-spread￾ing events have not yet been identified for NCIP, but they could become a feature as the epidemic progresses. Although delays between the onset of illness and seeking medical attention were generally short, with 27% of patients seeking attention within 2 days after onset, delays to hospitaliza￾tion were much longer, with 89% of patients not being hospitalized until at least day 5 of illness (Fig. 2). This indicates the difficulty in identify￾ing and isolating cases at an earlier stage of disease. It may be necessary to commit consider￾able resources to testing in outpatient clinics and emergency departments for proactive case finding, both as part of the containment strategy in locations without local spread yet as well as to permit earlier clinical management of cases. Such an approach would also provide important infor￾mation on the subclinical infections for a better assessment of severity. Our preliminary estimate of the incubation period distribution provides important evidence to support a 14-day medical observation period or quarantine for exposed persons. Our estimate Figure 3. Detailed Information on Exposures and Dates of Illness Onset in Five Clusters Including 16 Cases. Numbers in boxes are calendar dates in December 2019 and January 2020. Data from the 5 secondary cases (patients who had clear exposure to only one index case and had no other potential source of infection) were used to estimate the serial interval distribution. The first four clusters were identified in Wuhan, and the fifth cluster was identified in Huanggang. Case 2.1. F62 index 3 Onset Case 2.2. M64 Cluster 2 (December 2019–January 2020) Onset 27 Case 3.1. M49 index 15 Onset Case 3.2. F48 Case 3.3. M78 19 Onset Case 3.4. M50 20 Onset Cluster 3 (December 2019) Onset 12 22 Onset Case 4.2. M51 Case 4.3. F25 24 Onset Cluster 4 (December 2019) Case 4.1. F52 index Onset 21 Case 1.1. M61 index Case 1.3. F31 29 Onset Cluster 1 (December 2019) Onset 20 Onset Case 1.2. F57 25 Exposure to wet market Exposure to other cases Exposure to wet market and other cases Exposure not determined Case 5.1. M32 index 11 Onset Case 5.2. F28 Case 5.3. M57 13 Onset Case 5.4. F 16 Onset Cluster 5 (January 2020) Onset 4 Case Serial Interval (days) Data from the 5 Clusters Used in the Estimation of Serial Interval 5 9 3 7 7 7 1.2 1.3 2.2 3.3 4.3 5.2 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