Influence of COVID-19 Infection on Early Pregnancy Outcomes in Different Periods Around Frozen Embryo Transfer (preprint)

Purpose The study aimed to investigate the potential influence of COVID-19 infection on embryo implantation and early development in women undergoing frozen embryo transfer(FET), with a specific focus on infections occurring at different periods around FET.Methods A retrospective analysis was performed on women who had undergone FET during a period marked by a significant surge in COVID-19 infection in Shanghai. All enrolled women experienced their first documented COVID-19 infection around the time of FET, ensuring that infections did not occur prior to oocyte retrieval. Participants were categorized into six groups based on the timing of infection: uninfected, ≥ 60 days, < 60 days before FET, 0–14 days, 15–28 days, and 28–70 days after FET. Clinical outcomes were compared across these groups.Results The infection rate among the total of 709 cases was 78.28%. Infected individuals exhibited either asymptomatic or mild symptoms. The ongoing pregnancy rates for the first four groups were 40.7%, 44.4%, 40.5%, and 34.2% (P = 0.709) respectively, biochemical pregnancy rates (59.1% vs. 61.1% vs. 67.6% vs. 55.7%, P = 0.471) and clinical pregnancy rates (49.6% vs. 55.6% vs. 55.4% vs. 48.1%, P = 0.749), all showed no significant differences. Early spontaneous abortion rates across all six groups were 18.3%, 20.0%, 25.0%, 28.9%, 5.4%, and 19.0% respectively, with no significant differences (P = 0.113). Multivariable logistic analysis revealed no significant correlation between the infection and ongoing pregnancy.Conclusion Asymptomatic or mild COVID-19 infections occurring around FET do not appear to have a significant adverse impact on early pregnancy outcomes.

Equilibrium Oil Market Share under the COVID-19 Pandemic (preprint)

Equilibrium models for energy markets under uncertain demand and supply have attracted considerable attentions. This paper focuses on modelling crude oil market share under the COVID-19 pandemic using two-stage stochastic equilibrium. We describe the uncertainties in the demand and supply by random variables and provide two types of production decisions (here-and-now and wait-and-see). The here-and-now decision in the first stage does not depend on the outcome of random events to be revealed in the future and the wait-and-see decision in the second stage is allowed to depend on the random events in the future and adjust the feasibility of the here-and-now decision in rare unexpected scenarios such as those observed during the COVID-19 pandemic. We develop a fast algorithm to find a solution of the two-stage stochastic equilibrium. We show the robustness of the two-stage stochastic equilibrium model for forecasting the oil market share using the real market data from January 2019 to May 2020.

People’s perception of quarantine during the COVID-19 outbreak in Shantou, China (preprint)

Background Unprecedented public health measures have been implemented to combat the pandemic outbreak of the 2019 coronavirus disease (COVID-19) in China. The purpose of this research is to identify people’s perception of quarantine during the COVID-19Methods Semi-structured interviews with 30 participants were conducted, including 15 people who had been quarantined and 15 participants who had not been quarantined during the COVID-19 outbreak in Shantou, Southern China. Interview data were collected from February to March 2020. All interviews were audio-recorded and transcribed verbatim. The transcribed data were coded and analyzed to identify key themes.Results Four key themes concerning public health measures emerged: 1) A city-wide lockdown effectively aroused the public’s awareness of the seriousness of COVID-19, which was helpful for controlling the pandemic; however, it greatly impacted the economy and individuals’ way of life. 2) Hotel quarantine was an effective measure for medical observations. 3) Fear and lack of knowledge of quarantine were the main factors that affected quarantine compliance. 4) Less attention was paid to people’s mental health during the pandemic outbreak.Conclusions A lockdown and centralized hotel quarantines were effective ways to control the outbreak. Mandatory measures were highly supported. The media should educate the public about COVID-19. Psychological counseling is necessary for people who were quarantined long-term. The findings have implications for other countries and for emerging infectious diseases in the future.