ABSTRACT
Purpose To quantify and compare SARS-CoV-2 transmission potential across Alabama, Louisiana, and Mississippi and selected counties with populations in the 50th, 75th, and 100th percentile. Methods To determine the time-varying reproduction number R t of SARS-CoV-2, we applied the R package EpiEstim to the time series of daily incidence of confirmed cases. Median R t percentage change when policies changed was determined. Linear regression was performed between log 10 -transformed cumulative incidence and log 10 -transformed population size at four time points. Results Stay-at-home orders, face mask mandates, and vaccinations were associated with the most significant reductions in SARS-CoV-2 transmission in the three southern states. R t across the three states decreased significantly by 20% following stay-at-home orders. We observed varying degrees of reductions in R t across states following other policies. Rural Alabama counties experienced higher per capita cumulative cases relative to urban ones as of June 17 and October 17, 2020. Meanwhile, Louisiana and Mississippi saw the disproportionate impact of SARS-CoV-2 in rural counties compared to urban ones throughout the study period. Conclusion State and county policies had an impact on local pandemic trajectories. The rural-urban disparities in case burden call for evidence-based approaches in tailoring health promotion interventions and vaccination campaigns to rural residents.
ABSTRACT
Colombia announced the first case of severe acute respiratory syndrome coronavirus 2 on March 6, 2020. Since then, the country has reported a total of 4,240,982 cases and 106,544 deaths as of June 30, 2021. This motivates an investigation of the SARS-CoV-2 transmission dynamics at the national and regional level using case incidence data. Mathematical models are employed to estimate the transmission potential and perform short-term forecasts of the COVID-19 epidemic trajectory in Colombia. Furthermore, geographic heterogeneity of COVID-19 in Colombia is examined along with the analysis of mobility and social media trends, showing that the increase in mobility in July 2020 and January 2021 were correlated with surges in case incidence. The estimation of national and regional reproduction numbers shows sustained disease transmission during the early phase of the pandemic, exhibiting sub-exponential growth dynamics. Moreover, most recent estimates of reproduction number are >1.0 at the national and regional levels as of May 30, 2021. Further, the 30-day ahead short-term forecasts obtained from Richards model present a sustained decline in case counts in contrast to the sub-epidemic and GLM model. Nevertheless, our spatial analysis in Colombia shows distinct variations in incidence rate patterns across different departments that can be grouped into four distinct clusters. Lastly, the correlation of social media trends and adherence to social distancing measures is observed by the fact that a spike in the number of tweets indicating the stay-at-home orders was observed in November 2020 when the case incidence had already plateaued. Author summary As the COVID-19 pandemic continues to spread across Colombia, studies highlighting the intensity of the pandemic become imperative for appropriate resource allocation and informing public health policies. In this study we utilize mathematical models to infer the transmission dynamics of SARS-CoV-2 at the regional and national level as well as short-term forecast the COVID-19 epidemic trajectory. Moreover, we examine the geographic heterogeneity of the COVID-19 case incidence in Colombia along with the analysis of mobility and social media trends in relation to the observed COVID-19 case incidence in the country. The estimates of reproduction numbers at the national and regional level show sustained disease transmission as of May 30, 2021. Moreover, the 30-day ahead short-term forecasts for the most recent time-period (June 1-June 30, 2021) generated from the mathematical models needs to be interpreted with caution as the Richards model point towards a sustained decline in case incidence contrary to the GLM and sub-epidemic wave model. Nevertheless, the spatial analysis in Colombia shows distinct variations in incidence rate patterns across different departments that can be grouped into four distinct clusters. Lastly, the social media and mobility trends explain the occurrence of case resurgences over the time.
Subject(s)
COVID-19 , Coronavirus InfectionsABSTRACT
The study characterized COVID-19 transmission in Ghana in 2020-21 by estimating the time-varying reproduction number (R t ) and exploring its association with various public health interventions at the national and regional levels. Ghana experienced four pandemic waves with epidemic peaks in July 2020, and January, August and December, 2021. The epidemic peak was the highest nationwide in December 2021 with R t ≥2. Throughout 2020-21, per-capita cumulative case count by region increased with population size. Mobility data suggested negative correlation between R t and staying home in the first 90 days of the pandemic. The relaxation of movement restrictions and religious gatherings were not associated with increased R t in the regions with lower case burdens. R t decreased from above 1 when schools reopened in January 2021 to below 1 after vaccination rollout in March 2021. Findings indicated most public health interventions were associated with R t reduction at the national and regional levels.