Impact of vaccine prioritization strategies on mitigating COVID-19: an agent-based simulation study using an urban region in the United States.

BACKGROUND: Approval of novel vaccines for COVID-19 had brought hope and expectations, but not without additional challenges. One central challenge was understanding how to appropriately prioritize the use of limited supply of vaccines. This study examined the efficacy of the various vaccine prioritization strategies using the vaccination campaign underway in the U.S. METHODS: The study developed a granular agent-based simulation model for mimicking community spread of COVID-19 under various social interventions including full and partial closures, isolation and quarantine, use of face mask and contact tracing, and vaccination. The model was populated with parameters of disease natural history, as well as demographic and societal data for an urban community in the U.S. with 2.8 million residents. The model tracks daily numbers of infected, hospitalized, and deaths for all census age-groups. The model was calibrated using parameters for viral transmission and level of community circulation of individuals. Published data from the Florida COVID-19 dashboard was used to validate the model. Vaccination strategies were compared using a hypothesis test for pairwise comparisons. RESULTS: Three prioritization strategies were examined: a minor variant of CDC's recommendation, an age-stratified strategy, and a random strategy. The impact of vaccination was also contrasted with a no vaccination scenario. The study showed that the campaign against COVID-19 in the U.S. using vaccines developed by Pfizer/BioNTech and Moderna 1) reduced the cumulative number of infections by 10% and 2) helped the pandemic to subside below a small threshold of 100 daily new reported cases sooner by approximately a month when compared to no vaccination. A comparison of the prioritization strategies showed no significant difference in their impacts on pandemic mitigation. CONCLUSIONS: The vaccines for COVID-19 were developed and approved much quicker than ever before. However, as per our model, the impact of vaccination on reducing cumulative infections was found to be limited (10%, as noted above). This limited impact is due to the explosive growth of infections that occurred prior to the start of vaccination, which significantly reduced the susceptible pool of the population for whom infection could be prevented. Hence, vaccination had a limited opportunity to reduce the cumulative number of infections. Another notable observation from our study is that instead of adhering strictly to a sequential prioritizing strategy, focus should perhaps be on distributing the vaccines among all eligible as quickly as possible, after providing for the most vulnerable. As much of the population worldwide is yet to be vaccinated, results from this study should aid public health decision makers in effectively allocating their limited vaccine supplies.

Evidence of altered brain regulatory gene expression in tobacco-exposed fetuses.

AIM: We sought to determine the association between prenatal smoking status and expression of fetal brain regulatory genes. METHODS: At delivery, we collected information from parturient women on prenatal smoking habits and analyzed salivary cotinine levels. We obtained neonatal umbilical cord blood and extracted total RNA. We then employed the quantitative polymerase chain reaction (QPCR) analyses and the comparative CT method to calculate the relative gene expression of selected fetal brain regulatory genes responsible for (1) brain growth (brain-derived neutrotrophic factor, BDNF), (2) myelination (proteolipidic protein 1, PLP1 and myelin basic protein, MBP), and (3) neuronal migration and cell-cell interactions during fetal brain development or RLN. The χ2-test, analysis of variance (ANOVA), and the Grubb test were used to evaluate the relationship between prenatal smoking status and relative gene expression levels. Further analysis using bootstrapping was performed to assess the precision of our estimates. RESULTS: Of the 39 maternal-infant dyads included in this study, 25.6% were non-smokers, 43.6% were passive smokers and 30.8% were active smokers. The results showed down-regulation of the selected fetal brain regulatory genes among active smokers. CONCLUSIONS: These findings represent preliminary evidence in humans that intrauterine tobacco exposure impacts fetal brain programming. Future studies are warranted to examine whether our findings represent potential mechanisms through which adverse childhood/adult-onset cognitive and behavioral outcomes that have been previously linked to intrauterine exposure occur.

Impact assessment of full and partial stay-at-home orders, face mask usage, and contact tracing: An agent-based simulation study of COVID-19 for an urban region.

PURPOSE: Social intervention strategies to mitigate COVID-19 are examined using an agent-based simulation model. Outbreak in a large urban region, Miami-Dade County, Florida, USA is used as a case study. Results are intended to serve as a planning guide for decision makers. METHODS: The simulation model mimics daily social mixing behavior of the susceptible and infected generating the spread. Data representing demographics of the region, virus epidemiology, and social interventions shapes model behavior. Results include daily values of infected, reported, hospitalized, and dead. RESULTS: Results show that early implementation of complete stay-at-home order is effective in flattening and reversing the infection growth curve in a short period of time. Whereas, using Florida's Phase II plan alone could result in 75% infected and end of pandemic via herd immunity. Universal use of face masks reduced infected by 20%. A further reduction of 66% was achieved by adding contact tracing with a target of identifying 50% of the asymptomatic and pre-symptomatic. CONCLUSIONS: In the absence of a vaccine, the strict stay-at-home order, though effective in curbing a pandemic outbreak, leaves a large proportion of the population susceptible. Hence, there should be a strong follow up plan of social distancing, use of face mask, contact tracing, testing, and isolation of infected to minimize the chances of large-scale resurgence of the disease. However, as the economic cost of the complete stay-at-home-order is very high, it can perhaps be used only as an emergency first response, and the authorities should be prepared to activate a strong follow up plan as soon as possible. The target level for contact tracing was shown to have a nonlinear impact on the reduction of the percentage of population infected. Increase in contact tracing target from 20% to 30% appeared to provide the largest incremental benefit.

Community-based fortified dietary intervention improved health outcomes among low-income African-American women.

Poor dietary exposure disproportionately affects African-Americans and contributes to the persistence of disparities in health outcomes. In this study, we hypothesized that fortified dietary intervention (FDI) will improve measured dietary and related health outcomes and will be acceptable among low-income African-American women living in Tampa, FL. These objectives were tested using a prospective experimental study using pretest and posttest design with a control group, using a community-based participatory research approach. The intervention (FDI) was designed by the community through structural modification of a preexisting, diet-based program by the addition of a physical and mental health component. Paired sample t tests were used to examine preintervention and postintervention changes in study outcomes. A total of 49 women participated in the study, 26 in the FDI group and 23 controls. Two weeks postintervention, there were significant improvements in waist circumference and health-related quality of life related to physical health (P< .0001), physical fitness subscores (P= .002), and nutritional subscores (P= .001) in the FDI group. Among overweight/obese women, improvement in health-related quality of life related to physical health, a significant decrease in depressive score, and a reduction in waist circumference were noted. In the control group, a decrease in waist circumference was observed. Implementation of the FDI through a community-based participatory research approach is feasible and effective among low-income African-American women in general and overweight/obese women in particular. Social reengineering of a nutritional intervention coupled with community-based approach will enhance health outcomes of low-income women.