Browsing by Author "Ajelli, Marco"

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    Case fatality risk of the first pandemic wave of novel coronavirus disease 2019 (COVID-19) in China
    (Oxford University Press, 2020-05-15) Deng, Xiaowei; Yang, Juan; Wang, Wei; Wang, Xiling; Zhou, Jiaxin; Chen, Zhiyuan; Li, Jing; Chen, Yinzi; Yan, Han; Zhang, Juanjuan; Zhang, Yongli; Wang, Yan; Qiu, Qi; Gong, Hui; Wei, Xianglin; Wang, Lili; Sun, Kaiyuan; Wu, Peng; Ajelli, Marco; Cowling, Benjamin J.; Viboud, Cecile; Yu, Hongjie; Epidemiology, School of Public Health
    Objective To assess the case fatality risk (CFR) of COVID-19 in mainland China, stratified by region and clinical category, and estimate key time-to-event intervals. Methods We collected individual information and aggregated data on COVID-19 cases from publicly available official sources from December 29, 2019 to April 17, 2020. We accounted for right-censoring to estimate the CFR and explored the risk factors for mortality. We fitted Weibull, gamma, and lognormal distributions to time-to-event data using maximum-likelihood estimation. Results We analyzed 82,719 laboratory-confirmed cases reported in mainland China, including 4,632 deaths, and 77,029 discharges. The estimated CFR was 5.65% (95%CI: 5.50%-5.81%) nationally, with highest estimate in Wuhan (7.71%), and lowest in provinces outside Hubei (0.86%). The fatality risk among critical patients was 3.6 times that of all patients, and 0.8-10.3 fold higher than that of mild-to-severe patients. Older age (OR 1.14 per year; 95%CI: 1.11-1.16), and being male (OR 1.83; 95%CI: 1.10-3.04) were risk factors for mortality. The time from symptom onset to first healthcare consultation, time from symptom onset to laboratory confirmation, and time from symptom onset to hospitalization were consistently longer for deceased patients than for those who recovered. Conclusions Our CFR estimates based on laboratory-confirmed cases ascertained in mainland China suggest that COVID-19 is more severe than the 2009 H1N1 influenza pandemic in hospitalized patients, particularly in Wuhan. Our study provides a comprehensive picture of the severity of the first wave of the pandemic in China. Our estimates can help inform models and the global response to COVID-19.
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    Effectiveness of regional restrictions in reducing SARS-CoV-2 transmission during the second wave of COVID-19, Italy
    (Cold Spring Harbor Laboratory Press, 2021) Manica, Mattia; Guzzetta, Giorgio; Riccardo, Flavia; Valenti, Antonio; Poletti, Piero; Marziano, Valentina; Trentini, Filippo; Andrianou, Xanthi; Urdiales, Alberto Mateo; del Manso, Martina; Fabiani, Massimo; Vescio, Maria Fenicia; Spuri, Matteo; Petrone, Daniele; Bella, Antonino; Iavicoli, Sergio; Ajelli, Marco; Brusaferro, Silvio; Pezzotti, Patrizio; Merler, Stefano; Epidemiology, School of Public Health
    To counter the second COVID-19 wave, the Italian government has adopted a scheme of three sets of restrictions (coded as yellow, orange, and red) imposed on a regional basis. We estimate that milder restrictions in regions at lower risk (yellow) resulted in a transmissibility reduction of about 18%, leading to a reproduction number Rt of about 0.99. Stricter measures (orange and red) led to reductions of 34% and 45% and Rt values of about 0.89 and 0.77 respectively.