BACKGROUND: Understanding the characteristics and natural history of novel pathogens is crucial to inform successful control measures. Japan was one of the first affected countries in the COVID-19 pandemic reporting their first case on 14 January 2020. Interventions including airport screening, contact tracing, and cluster investigations were quickly implemented. Here we present insights from the first 3 months of the epidemic in Japan based on detailed case data. METHODS: We conducted descriptive analyses based on information systematically extracted from individual case reports from 13 January to 31 March 2020 including patient demographics, date of report and symptom onset, symptom progression, travel history, and contact type. We analysed symptom progression and estimated the time-varying reproduction number, Rt, correcting for epidemic growth using an established Bayesian framework. Key delays and the age-specific probability of transmission were estimated using data on exposures and transmission pairs. RESULTS: The corrected fitted mean onset-to-reporting delay after the peak was 4 days (standard deviation: ± 2 days). Early transmission was driven primarily by returning travellers with Rt peaking at 2.4 (95% CrI: 1.6, 3.3) nationally. In the final week of the trusted period (16-23 March 2020), Rt accounting for importations diverged from overall Rt at 1.1 (95% CrI: 1.0, 1.2) compared to 1.5 (95% CrI: 1.3, 1.6), respectively. Household (39.0%) and workplace (11.6%) exposures were the most frequently reported potential source of infection. The estimated probability of transmission was assortative by age with individuals more likely to infect, and be infected by, contacts in a similar age group to them. Across all age groups, cases most frequently onset with cough, fever, and fatigue. There were no reported cases of patients < 20 years old developing pneumonia or severe respiratory symptoms. CONCLUSIONS: Information collected in the early phases of an outbreak are important in characterising any novel pathogen. The availability of timely and detailed data and appropriate analyses is critical to estimate and understand a pathogen's transmissibility, high-risk settings for transmission, and key symptoms. These insights can help to inform urgent response strategies.
BACKGROUND: Understanding the characteristics and natural history of novel pathogens is crucial to inform successful control measures. Japan was one of the first affected countries in the COVID-19 pandemic reporting their first case on 14 January 2020. Interventions including airport screening, contact tracing, and cluster investigations were quickly implemented. Here we present insights from the first 3 months of the epidemic in Japan based on detailed case data. METHODS: We conducted descriptive analyses based on information systematically extracted from individual case reports from 13 January to 31 March 2020 including patient demographics, date of report and symptom onset, symptom progression, travel history, and contact type. We analysed symptom progression and estimated the time-varying reproduction number, Rt, correcting for epidemic growth using an established Bayesian framework. Key delays and the age-specific probability of transmission were estimated using data on exposures and transmission pairs. RESULTS: The corrected fitted mean onset-to-reporting delay after the peak was 4 days (standard deviation: ± 2 days). Early transmission was driven primarily by returning travellers with Rt peaking at 2.4 (95% CrI: 1.6, 3.3) nationally. In the final week of the trusted period (16-23 March 2020), Rt accounting for importations diverged from overall Rt at 1.1 (95% CrI: 1.0, 1.2) compared to 1.5 (95% CrI: 1.3, 1.6), respectively. Household (39.0%) and workplace (11.6%) exposures were the most frequently reported potential source of infection. The estimated probability of transmission was assortative by age with individuals more likely to infect, and be infected by, contacts in a similar age group to them. Across all age groups, cases most frequently onset with cough, fever, and fatigue. There were no reported cases of patients < 20 years old developing pneumonia or severe respiratory symptoms. CONCLUSIONS: Information collected in the early phases of an outbreak are important in characterising any novel pathogen. The availability of timely and detailed data and appropriate analyses is critical to estimate and understand a pathogen's transmissibility, high-risk settings for transmission, and key symptoms. These insights can help to inform urgent response strategies.
Authors: Tini Garske; Judith Legrand; Christl A Donnelly; Helen Ward; Simon Cauchemez; Christophe Fraser; Neil M Ferguson; Azra C Ghani Journal: BMJ Date: 2009-07-14
Authors: Annemarie B Docherty; Ewen M Harrison; Christopher A Green; Hayley E Hardwick; Riinu Pius; Lisa Norman; Karl A Holden; Jonathan M Read; Frank Dondelinger; Gail Carson; Laura Merson; James Lee; Daniel Plotkin; Louise Sigfrid; Sophie Halpin; Clare Jackson; Carrol Gamble; Peter W Horby; Jonathan S Nguyen-Van-Tam; Antonia Ho; Clark D Russell; Jake Dunning; Peter Jm Openshaw; J Kenneth Baillie; Malcolm G Semple Journal: BMJ Date: 2020-05-22
Authors: Olivia V Swann; Karl A Holden; Lance Turtle; Louisa Pollock; Cameron J Fairfield; Thomas M Drake; Sohan Seth; Conor Egan; Hayley E Hardwick; Sophie Halpin; Michelle Girvan; Chloe Donohue; Mark Pritchard; Latifa B Patel; Shamez Ladhani; Louise Sigfrid; Ian P Sinha; Piero L Olliaro; Jonathan S Nguyen-Van-Tam; Peter W Horby; Laura Merson; Gail Carson; Jake Dunning; Peter J M Openshaw; J Kenneth Baillie; Ewen M Harrison; Annemarie B Docherty; Malcolm G Semple Journal: BMJ Date: 2020-08-27
Authors: Bruce Aylward; Philippe Barboza; Luke Bawo; Eric Bertherat; Pepe Bilivogui; Isobel Blake; Rick Brennan; Sylvie Briand; Jethro Magwati Chakauya; Kennedy Chitala; Roland M Conteh; Anne Cori; Alice Croisier; Jean-Marie Dangou; Boubacar Diallo; Christl A Donnelly; Christopher Dye; Tim Eckmanns; Neil M Ferguson; Pierre Formenty; Caroline Fuhrer; Keiji Fukuda; Tini Garske; Alex Gasasira; Stephen Gbanyan; Peter Graaff; Emmanuel Heleze; Amara Jambai; Thibaut Jombart; Francis Kasolo; Albert Mbule Kadiobo; Sakoba Keita; Daniel Kertesz; Moussa Koné; Chris Lane; Jered Markoff; Moses Massaquoi; Harriet Mills; John Mike Mulba; Emmanuel Musa; Joel Myhre; Abdusalam Nasidi; Eric Nilles; Pierre Nouvellet; Deo Nshimirimana; Isabelle Nuttall; Tolbert Nyenswah; Olushayo Olu; Scott Pendergast; William Perea; Jonathan Polonsky; Steven Riley; Olivier Ronveaux; Keita Sakoba; Ravi Santhana Gopala Krishnan; Mikiko Senga; Faisal Shuaib; Maria D Van Kerkhove; Rui Vaz; Niluka Wijekoon Kannangarage; Zabulon Yoti Journal: N Engl J Med Date: 2014-09-22 Impact factor: 91.245