The dynamics of coronavirus disease 2019 (COVID-19) transmissibility are yet to be fully understood. Better understanding of the transmission dynamics is important for the development and evaluation ...of effective control policies.
To delineate the transmission dynamics of COVID-19 and evaluate the transmission risk at different exposure window periods before and after symptom onset.
This prospective case-ascertained study in Taiwan included laboratory-confirmed cases of COVID-19 and their contacts. The study period was from January 15 to March 18, 2020. All close contacts were quarantined at home for 14 days after their last exposure to the index case. During the quarantine period, any relevant symptoms (fever, cough, or other respiratory symptoms) of contacts triggered a COVID-19 test. The final follow-up date was April 2, 2020.
Secondary clinical attack rate (considering symptomatic cases only) for different exposure time windows of the index cases and for different exposure settings (such as household, family, and health care).
We enrolled 100 confirmed patients, with a median age of 44 years (range, 11-88 years), including 44 men and 56 women. Among their 2761 close contacts, there were 22 paired index-secondary cases. The overall secondary clinical attack rate was 0.7% (95% CI, 0.4%-1.0%). The attack rate was higher among the 1818 contacts whose exposure to index cases started within 5 days of symptom onset (1.0% 95% CI, 0.6%-1.6%) compared with those who were exposed later (0 cases from 852 contacts; 95% CI, 0%-0.4%). The 299 contacts with exclusive presymptomatic exposures were also at risk (attack rate, 0.7% 95% CI, 0.2%-2.4%). The attack rate was higher among household (4.6% 95% CI, 2.3%-9.3%) and nonhousehold (5.3% 95% CI, 2.1%-12.8%) family contacts than that in health care or other settings. The attack rates were higher among those aged 40 to 59 years (1.1% 95% CI, 0.6%-2.1%) and those aged 60 years and older (0.9% 95% CI, 0.3%-2.6%).
In this study, high transmissibility of COVID-19 before and immediately after symptom onset suggests that finding and isolating symptomatic patients alone may not suffice to contain the epidemic, and more generalized measures may be required, such as social distancing.
Mussel‐inspired polydopamine (PDA) deposition offers a promising route to fabricate multifunctional coatings for various materials. However, PDA deposition is generally a time‐consuming process, and ...PDA coatings are unstable in acidic and alkaline media, as well as in polar organic solvents. We report a strategy to realize the rapid deposition of PDA by using CuSO4/H2O2 as a trigger. Compared to the conventional processes, our strategy shows the fastest deposition rate reported to date, and the PDA coatings exhibit high uniformity and enhanced stability. Furthermore, the PDA‐coated porous membranes have excellent hydrophilicity, anti‐oxidant properties, and antibacterial performance. This work demonstrates a useful method for the environmentally friendly, cost‐effective, and time‐saving fabrication of PDA coatings.
Mussel‐inspired surfaces: A facile and robust approach to rapidly construct polydopamine (PDA) coatings on various substrates is presented. The CuSO4/H2O2‐triggered PDA coatings show high uniformity, enhanced stability, excellent hydrophilicity, antioxidant ability, and antibacterial performance.
An unprecedented surge of COVID-19 cases in Taiwan in May 2021 led the government to implement strict nationwide control measures beginning May 15. During the surge, the government was able to bring ...the epidemic under control without a complete lockdown despite the cumulative case count reaching >14,400 and >780 deaths. We investigated the effectiveness of the public health and social measures instituted by the Taiwan government by quantifying the change in the effective reproduction number, which is a summary measure of the ability of the pathogen to spread through the population. The control measures that were instituted reduced the effective reproduction number from 2.0–3.3 to 0.6–0.7. This decrease was correlated with changes in mobility patterns in Taiwan, demonstrating that public compliance, active case finding, and contact tracing were effective measures in preventing further spread of the disease.
•Robust contact tracing with an integrated system effectively intervenes early transmission of COVID-19 in Taiwan.•Developing an integrated management system to support traditional contact tracing is ...critical in response to control the spread of COVID-19.•Management tools augment the capacity and decrease workloads of contact tracers, which improve contact tracing effectiveness.
Comprehensive case investigation and contact tracing are crucial to prevent community spread of COVID-19. We demonstrated a utility of using traditional contact tracing measures supplemented with symptom tracking and contact management system to assist public health workers with high efficiency.
A centralized contact tracing system was developed to support data linkage, cross-jurisdictional coordination, and follow-up of contacts’ health status. We illustrated the process of how digital tools support contact tracing and management of COVID-19 cases and measured the timeliness from case detection to contact monitoring to evaluate system performance.
Among the 8051 close contacts of the 487 confirmed cases (16.5 close contacts/case, 95% CI 13.9–19.1), the median elapsed time from last exposure to quarantine was three days (IQR 1–5). By implementing the approach of self-reporting using automatic text-messages and web-app, the percentage of health status updates from self-reporting increased from 22.5% to 61.5%. The high proportion of secondary cases detected via contact tracing (88%) might reduce the R0 to under one and minimize the impact of local transmission in the community.
Comprehensive contact tracing and management with complementary technology would still be a pillar of strategies for containing outbreaks during de-escalation or early in the next wave of COVID-19 pandemic.
Mitigation of alkali-silica reaction (ASR) in concrete is essential for durable and sustainable constructions. In conventional Portland cement-based concrete, alumina-rich supplementary cementitious ...materials such as low-calcium fly ash and metakaolin have been successfully used to mitigate ASR. Such effect has not been investigated for alkali-activated slag based materials. In this study, ASR expansion, changes in mortar weight and pore solution alkalinity have been studied. XRD and SEM/EDX have been employed to examine the reaction products and degradation of aggregates. The results demonstrate that there is an optimum dosage of fly ash to reduce ASR expansion of the studied mortars, whereas ASR expansion decreases with increasing the amount of metakaolin. It is found that the amount of ASR product formed is minor in the studied mortars with highest expansion. The pore solution alkalinity of the studied mortars is the main factor which controls the ASR in the alkali-activated slag mortars.
Taiwan is one of the few countries with initial success in COVID-19 control without strict lockdown or school closure. The reasons remain to be fully elucidated.
To compare and evaluate the ...effectiveness of case-based (including contact tracing and quarantine) and population-based (including social distancing and facial masking) interventions for COVID-19 in Taiwan.
This comparative effectiveness study used a stochastic branching process model using COVID-19 epidemic data from Taiwan, an island nation of 23.6 million people, with no locally acquired cases of COVID-19 reported for 253 days between April and December 2020.
Effective reproduction number of COVID-19 cases (the number of secondary cases generated by 1 primary case) and the probability of outbreak extinction (0 new cases within 20 generations). For model development and calibration, an estimation of the incubation period (interval from exposure to symptom onset), serial interval (time between symptom onset in an infector-infectee pair), and the statistical distribution of the number of any subsequent infections generated by 1 primary case was calculated.
This study analyzed data from 158 confirmed COVID-19 cases (median age, 45 years; interquartile range, 25-55 years; 84 men 53%). An estimated 55% (95% credible interval CrI, 41%-68%) of transmission events occurred during the presymptomatic stage. In our estimated analysis, case detection, contact tracing, and 14-day quarantine of close contacts (regardless of symptoms) was estimated to decrease the reproduction number from the counterfactual value of 2.50 to 1.53 (95% CrI, 1.50-1.57), which would not be sufficient for epidemic control, which requires a value of less than 1. In our estimated analysis, voluntary population-based interventions, if used alone, were estimated to have reduced the reproduction number to 1.30 (95% CrI, 1.03-1.58). Combined case-based and population-based interventions were estimated to reduce the reproduction number to below unity (0.85; 95% CrI, 0.78-0.89). Results were similar for additional analyses with influenza data and sensitivity analyses.
In this comparative effectiveness research study, the combination of case-based and population-based interventions (with wide adherence) may explain the success of COVID-19 control in Taiwan in 2020. Either category of interventions alone would have been insufficient, even in a country with an effective public health system and comprehensive contact tracing program. Mitigating the COVID-19 pandemic requires the collaborative effort of public health professionals and the general public.
The coronavirus disease 2019 (COVID-19) pandemic has become severe threats to economic, societal, and healthcare systems. To analyze the epidemiological characteristics of the COVID-19 outbreak in ...Taiwan and evaluate the key interventions, we conducted a retrospective cohort study during January 17–June 30, 2020. As of June 30, the COVID-19 outbreak, including 447 laboratory-confirmed cases, was eliminated by mixed approaches: border control, enhanced surveillance, case detection with contact tracing, quarantine, and population-based interventions like face mask use. The improvement of median time from disease onset to notification (5 days range −3 to 27 before March 1 to 1 day range −8 to 22 after March 1) suggested the timeliness and comprehensiveness of surveillance and contact tracing. Travel restrictions with quarantine, resulting in fewer clusters, were also complementary to minimize disease spread. Under combined interventions, Taiwan successfully contained the COVID-19 spread within the country and minimized its impact on the society.
Diabetic cardiomyopathy (DCM) is a serious complication of diabetes mellitus (DM). One of the hallmarks of the DCM is enhanced oxidative stress in myocardium. The aim of this study was to research ...the underlying mechanisms involved in the effects of dapagliflozin (Dap) on myocardial oxidative stress both in streptozotocin-induced DCM rats and rat embryonic cardiac myoblasts H9C2 cells exposed to high glucose (33.0 mM). In
in vivo
studies, diabetic rats were given Dap (1 mg/ kg/ day) by gavage for eight weeks. Dap treatment obviously ameliorated cardiac dysfunction, and improved myocardial fibrosis, apoptosis and oxidase stress. In
in vitro
studies, Dap also attenuated the enhanced levels of reactive oxygen species and cell death in H9C2 cells incubated with high glucose. Mechanically, Dap administration remarkably reduced the expression of membrane-bound nicotinamide adenine dinucleotide phosphate (NADPH) oxidase subunits gp91phox and p22phox, suppressed the p67phox subunit translocation to membrane, and decreased the compensatory elevated copper, zinc superoxide dismutase (Cu/Zn-SOD) protein expression and total SOD activity both
in vivo
and
in vitro
. Collectively, our results indicated that Dap protects cardiac myocytes from damage caused by hyperglycemia through suppressing NADPH oxidase-mediated oxidative stress.
•Aligning risk management to timely policy planning via rapid risk assessments led to effective response to COVID-19.•Robust event-based surveillance system contributed to early detection of the ...COVID-19 outbreak.•A whole-of-government approach achieved policy coherence and increased efficiency in COVID-19 control.
Event-based surveillance and rapid risk assessment for acute public health events are essential in emerging infectious disease control. Since detecting the unusual signal in Wuhan in December 2019, Taiwan has been aligning risk management to policy planning via conducting regular risk assessments to combat the coronavirus disease 2019 (COVID-19). This article aims to provide some insights into Taiwan's experiences and corresponding actions for the outbreak.
The COVID-19 risk level in Taiwan was raised to “moderate-to-high” in mid-January 2020 when neighboring countries had reported cases and the human-to-human transmission became obvious. The risk level became “high” on 24 January due to China's escalating epidemic situation and imposed a lockdown in Wuhan. We learned that the commander recognized the importance of risk assessments and considered advice from the experts was crucial in making the correct decision at the early stage of the crisis.
Given the surge of COVID-19 cases globally, understanding the evidence-driven mobilizations via detailed risk assessments in Taiwan may be an example worth considering for other countries. We believe that strengthening a global epidemic intelligence network and sharing information in a timely and transparent manner are essential for confronting new challenges of COVID-19 and other emerging infectious diseases.
To investigate the capability, properties, and molecular mechanism of inulin fermentation by lactic acid bacteria (LAB) from Sichuan pickle.
A total of 79 LAB strains were purified from 30 aged ...Sichuan pickle brine samples, and only 21 Lactiplantibacillus plantarum strains (26.58%, 21/79) derived from 15 samples grew well through utilizing inulin as a carbon source. The fermentation tests through using long-chain inulin (lc-inulin) as a carbon source showed that only 6 L. plantarum strains grew well, while other 15 strains could only utilize short-chain oligofructose (FOS), and thin-layer chromatography analysis evidenced a strain specificity of inulin consumption patterns. Lactiplantibacillus plantarum YT041 is a vigorous inulin fermenter, and whole genome sequencing data revealed that sacPTS1 and fosRABCDXE operons might be associated with the fermentation of FOS and lc-inulin, respectively.
The phenotype of inulin consumption is commonly present in LAB from Sichuan pickle, which is strain-specific and largely depends on their specific ecological niche and degree of polymerization.
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