Reconstructing early transmission networks of SARS-CoV-2 using a genomic mutation model.

The coronavirus disease 2019 (COVID-19) pandemic has greatly damaged human society, but the origins and early transmission patterns of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) pathogen remain unclear. Here, we reconstructed the transmission networks of SARS-CoV-2 during the first three and six months since its first report based on ancestor-offspring relationships using BANAL-52-referenced mutations. We explored the position (i.e., root, middle, or tip) of early detected samples in the evolutionary tree of SARS-CoV-2. In total, 6 799 transmission chains and 1 766 transmission networks were reconstructed, with chain lengths ranging from 1-9 nodes. The root node samples of the 1 766 transmission networks were from 58 countries or regions and showed no common ancestor, indicating the occurrence of many independent or parallel transmissions of SARS-CoV-2 when first detected (i.e., all samples were located at the tip position of the evolutionary tree). No root node sample was found in any sample ( n=31, all from the Chinese mainland) collected in the first 15 days from 24 December 2019. Results using six-month data or RaTG13-referenced mutation data were similar. The reconstruction method was verified using a simulation approach. Our results suggest that SARS-CoV-2 may have already been spreading independently worldwide before the outbreak of COVID-19 in Wuhan, China. Thus, a comprehensive global survey of human and animal samples is essential to explore the origins of SARS-CoV-2 and its natural reservoirs and hosts.

Transmission rate and control efficiency of COVID-19 was lower in warm and wet climate.

COVID-19 has caused huge damage to public health around the world, revealing the influencing factors are essential to take effective control. By using a global dataset covering 617 time series over the world, we estimated the transmission parameters and modeled human and climate effects on COVID-19 transmission. We found that the average transmission rate was lower in warm climate over the world and in wet climate (more precipitation) in Europe. The maximum transmission rate was lower in warm climate in the world, China and USA, and in wet climate in China. The control efficiency in the world, China, and USA was lower in warm and wet condition. In general, our results indicate that warm and wet climate do not favor transmission and human intervention of COVID-19, and COVID-19 transmission rate would be lower in warm and wet seasons or regions than in dry and cold ones.

Modeling analysis reveals the transmission trend of COVID-19 and control efficiency of human intervention.

BACKGROUND: A novel coronavirus disease (COVID-19) has caused huge damage to public health around the world. Revealing the transmission dynamics of COVID-19 and control efficiency is important for containing the spread of the virus. METHODS: By using a logistic growth model, we estimated the transmission parameters of COVID-19 in China and six other countries (Republic of Korea, Iran, Italy, Spain, France and Germany). The transmission parameters represent the maximum daily increase rate in the early stages of the epidemic and the control efficiency under human intervention. The control efficiency was determined by the significant decrease of the daily increase rate in time and cumulative cases. RESULTS: We found the daily increase rate of cumulative cases of COVID-19 decreased significantly in both time and cumulative cases in all countries, but the decreasing trend was not further reduced in other countries except for China and Republic of Korea. The response of the daily increase rate to control measures was much earlier than the number of new cases. CONCLUSIONS: Our results suggested that lockdown at the epicenter and social distancing effectively reduced the spread of COVID-19 in the early stage, but identification and isolation of patients, suspected cases and people with close contact at a community level is essential in further reduction of the daily increase rate of COVID-19.

Combating COVID-19 Together: China’s Collaborative Response and the Role of Business Associations

Drawing on data from Zhejiang Province, this study explores China?s collaborative response to COVID-19 in which business associations played a critical role. Consistent with existing literature on cross-sector collaboration and nonprofit contributions in extreme events, the preliminary findings of this study carry significant implications for future research to advance new knowledge. Specifically, two important next steps of future research that hold considerable promise?examining the overwhelming impact of the institutional environment on collaboration and accounting for the complex mechanisms in which multiple components of collaboration create outcomes through a configurational approach?emerged from this study. In addition, the practical implications of these findings are highlighted.