ABSTRACT
ObjectivesThe US and rest of the world have suffered from the COVID-19 pandemic for over a year. The high transmissibility and severity of this virus have provoked governments to adopt a variety of mitigation strategies. Some of these previous measures, such as social distancing and mask mandates, were effective in reducing the case growth rate yet became economically and administratively difficult to enforce as the pandemic continued. In late December 2020, COVID-19 vaccines were first approved in the US and states began a phased implementation of COVID-19 vaccination. However, there is limited quantitative evidence regarding the effectiveness of the phased COVID-19 vaccination. This study aims to provide a rapid assessment of the adoption, reach, and effectiveness of the phased implementation of COVID-19 vaccination. MethodsWe utilize an event-study analysis to evaluate the effect of vaccination on the state-level, daily COVID-19 case growth rate. ResultsThrough this analysis, we assert that vaccination is effective in reducing the spread of COVID-19 shortly after the first shots were given. Specifically, the case growth rate declined by 0.124, 0.347, 0.345, 0.464, 0.490, and 0.756 percentage points corresponding to the 1-5, 6-10, 11-15, 16-20, 21-25, and 26 or more day periods after the initial shots. ConclusionsThe findings could be insightful for policymakers as they work to optimize vaccine distribution in later phases, and also for the public as the COVID-19 related health risk is a contentious issue.
ABSTRACT
ObjectTo develop the reliable RP-HPLC methods for the determination of salidroside, tyrosol, rosavin, rosin, and rosarin in the plants of Rhodiola L. and to evaluate their species from different habitats. Methods Method Ⅰ: methanol-water (0.5 mmol/L SDS in 1% acetic acid aqueous solution) system for the analysis of salidroside; method Ⅱ: acetonitrile-water system for rosavin; method Ⅲ: aqueous acetonitrile-phosphoric gradient system for salidroside, tyrosol, rosavin, rosin, and rosarin. Results The contents of salidroside in different species range from 0.021% to 1.420%, and those of rosavin in all species are very limited or undetected except in Rhodiola rosea L. and R. sachalinensis. The contents of the five marker ingredients are significantly species- and habitat-dependent. Conclusion Three RP-HPLC methods are established for quantitative analysis of the above five marker ingredients in the meantime, respectively. Evaluation of the quality of varied species of Rhodiola L. shows that R. rosea growing in Xinjiang Uygur Autonomous Region and R. sachalinensis growing in Jilin province are the two better species contained with abundant above-mentioned ingredients in China.
