Importance Several parameters driving the transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) remain unclear, including age-specific differences in infectivity and susceptibility, and the contribution of inapparent infections to transmission. Robust estimates of key time-to-event distributions remain scarce as well. Objective Illustrate SARS-CoV-2 transmission patterns and risk factors, and estimate key time-to-event distributions. Design, Setting, and Participants Individual-based data on 1,178 SARS-CoV-2 infected individuals and their 15,648 contacts identified by contact tracing monitoring over the period from January 13-April 02, 2020 were extracted from the notifiable infectious diseases reporting system in Hunan Province, China. Demographic characteristics, severity classification, exposure and travel history, and key clinical timelines were retrieved. Exposures Confirmed SARS-CoV-2 infection by positive polymerase chain reaction test result of respiratory samples, and exposure to SARS-CoV-2 infected individuals via household, relative, social, and other types of contacts. Main Outcomes and Measures The relative contribution of pre-symptomatic and asymptomatic transmission, key time-to-event parameters, and the effect of biological, demographic, and behavioral factors on SARS-CoV-2 infectivity and susceptibility were quantified. Results Among SARS-CoV-2 infected individuals, the estimated mean serial interval was 5.5 days (95%CI -5.0, 19.9) and the mean generation time was 5.5 days (95%CI 1.7, 11.6). Infectiousness was estimated to peak 1.8 days before symptom onset, with 95% of transmission events occurring between -7.6 days and 7.3 days from the date of symptom onset. The proportion of pre-symptomatic transmission was estimated at 62.5%, while a lower bound for the proportion of asymptomatic transmission was 3.5%. Infectiousness of SARS-CoV-2 was not significantly different between working-age adults (15-59 years old) and other age groups (0-14 years old: p-value=0.16; 60 years and over: p-value=0.33), whilst susceptibility to SARS-CoV-2 infection was estimated to increase with age (p-value=0.03). In addition, transmission risk was higher for household contacts (p-value<0.001), but decreased in later generations of a cluster (second generation: OR=0.13, p-value<0.001; generations 3-4: OR=0.05, p-value<0.001, relative to generation 1) and for those exposed to infectors with a larger number of contacts (p-value=0.04). Conclusions and Relevance These findings support the contribution of children to transmission and the importance of pre-symptomatic transmission, in turn highlighting the importance of large-scale testing, contact tracing activities, and the use of personnel protective equipment during the COVID-19 pandemic.

Background: Immune checkpoint inhibitor (ICI)–associated myocarditis is an uncommon and potentially fatal immune-related adverse event (irAE). Although corticosteroids are recommended as the first-line treatment by current guidelines, patients still have variable responses to it, and the guidelines vary significantly in terms of treatment strategies.Objectives: In this study, we performed a retrospective analysis of ICI-associated myocarditis in our hospital to propose a new comparative analysis to aid individualized treatment.Methods: We reviewed detailed records of 24 patients with confirmed ICI-associated myocarditis in our hospital from July 1, 2019, to April 1, 2021. Although all the cases in our study received recommended initial corticosteroid treatment according to the guidelines, different responses to corticosteroid were observed during the process of subsequent corticosteroid tapering. Basing on troponin cardiac troponin T rebound during corticosteroid tapering, we propose a new classification analysis of ICI-associated myocarditis that included two subgroups: corticosteroid-sensitive (n = 8) and corticosteroid-resistant group (n = 16).Results: Compared with corticosteroid-sensitive patients, larger doses of corticosteroid, longer period of treatment, and higher mortality rate were found in corticosteroid-resistant patients. Corticosteroid-resistant patients were characterized by more prominent ptosis, muscle weakness, elevated cardiac biomarkers, creatine kinase, and hepatic enzymes levels than that in the corticosteroid-sensitive patients. Tofacitinib (5 mg twice a day) was used in 11 corticosteroid-resistant patients, with seven patients recovered from ICI-associated myocarditis, showing a promising therapeutic effect.Conclusion: Our group analysis of corticosteroid responsiveness in patients with ICI-associated myocarditis may help clinicians to apply individualized treatment in this high-risk cohort. In addition, tofacitinib could provide clinical benefits when used early in the corticosteroid-resistant patients and may provide a new option for the treatment of ICI-associated myocarditis.

Biomass carbon material has a good potential as an anode for potassium-ion batteries (KIBs). However, it suffers from a low initial Coulombic efficiency (ICE), which hinders its mass adoption. The...