Analyzing the effects of quarantine, isolation, and vaccination on the spread of COVID-19 via a mathematical model

The main COVID-19 control strategies presently practiced are maintaining social distancing, quarantin-ing suspected exposures, and isolating infectious people. In this paper, a deterministic compartmental mathematical model is proposed considering these three control strategies. Based on the proposed model the effect of vaccination on the suppression of the disease is discussed. Critical vaccination rate and vaccinated population size relevant to disease suppression are determined based on the proposed mathematical model. Different forms of the most used key term in infectious disease modelling, reproduction number, are determined relevant to the proposed model. Sensitivity analysis of the reproduction numbers is done to identify model parameters mostly affecting the spread of the disease. Based on the reproduction number of the model disease controlling parameter regions are determined and graphical representations of those parameter regions are presented. Based on the results of the proposed mathematical model, it is observed that earlier implementation of the vaccination process is helpful to better control the disease. However, it takes considerable time to invent successful vaccinations for newly out-breaking diseases like COVID-19. Therefore, it took considerable time to start the vaccination process for COVID-19. It is observed that after starting a vaccination process at a particular rate it should continue until the vaccinated population reaches a critical size. © 2023, National Science Foundation. All rights reserved.

Increasing ventilation reduces SARS-CoV-2 airborne transmission in schools: A retrospective cohort study in Italy's Marche region.

Introduction: While increasing the ventilation rate is an important measure to remove inhalable virus-laden respiratory particles and lower the risk of infection, direct validation in schools with population-based studies is far from definitive. Methods: We investigated the strength of association between ventilation and SARS-CoV-2 transmission reported among the students of Italy's Marche region in more than 10,000 classrooms, of which 316 were equipped with mechanical ventilation. We used ordinary and logistic regression models to explore the relative risk associated with the exposure of students in classrooms. Results and discussion: For classrooms equipped with mechanical ventilation systems, the relative risk of infection of students decreased at least by 74% compared with a classroom with only natural ventilation, reaching values of at least 80% for ventilation rates >10 L s-1 student-1. From the regression analysis we obtained a relative risk reduction in the range 12%15% for each additional unit of ventilation rate per person. The results also allowed to validate a recently developed predictive theoretical approach able to estimate the SARS-CoV-2 risk of infection of susceptible individuals via the airborne transmission route. We need mechanical ventilation systems to protect students in classrooms from airborne transmission; the protection is greater if ventilation rates higher than the rate needed to ensure indoor air quality (>10 L s-1 student-1) are adopted. The excellent agreement between the results from the retrospective cohort study and the outcome of the predictive theoretical approach makes it possible to assess the risk of airborne transmission for any indoor environment.

Optimal quarantine, isolation, and social distancing strategies for COVID-19 based on a mathematical model

Around 221 countries in the world are currently suffering from the COVID-19 pandemic and the World Health Organization reported there are 217.7 million confirmed cases with 4.5 million deaths tolls as of 31st August 2021. Until a cure is found, it is more appropriate to follow the health guidelines recommended by authorities. Theoretically, forecasting the courses and possible outcomes of such a pandemic is crucial for healthcare sectors to make decisions in advance. This paper aims to find optimal quarantine, isolation, and social distancing strategies for COVID-19 based on the SEIQJR mathematical model with a proper cost analysis. Minimising the cost of the controlling process of diseases is very important for public health policymakers. An optimal control problem is considered with a proposed cost functional which is minimised to yield optimal control strategies. We subsequently insert an inequality state constraint to the problem by considering the possible maximum capacities of hospitals. Copyright © 2022 Inderscience Enterprises Ltd.

SARS-CoV-2 Prevalence among Outpatients during Community Transmission, Zambia, July 2020.

During the July 2020 first wave of severe acute respiratory syndrome coronavirus 2 in Zambia, PCR-measured prevalence was 13.4% among outpatients at health facilities, an absolute difference of 5.7% compared with prevalence among community members. This finding suggests that facility testing might be an effective strategy during high community transmission.

Considerations for Establishing Successful Coronavirus Disease Vaccination Programs in Africa.

The accelerated development of coronavirus disease (COVID-19) candidate vaccines is intended to achieve worldwide immunity. Ensuring COVID-19 vaccination is crucial to stemming the pandemic, reclaiming everyday life, and helping restore economies. However, challenges exist to deploying these vaccines, especially in resource-limited sub-Saharan Africa. In this article, we highlight lessons learned from previous efforts to scale up vaccine distribution and offer considerations for policymakers and key stakeholders to use for successful COVID-19 vaccination rollout in Africa. These considerations range from improving weak infrastructure for managing data and identifying adverse events after immunization to considering financing options for overcoming the logistical challenges of vaccination campaigns and generating demand for vaccine uptake. In addition, providing COVID-19 vaccination can be used to promote the adoption of universal healthcare, especially in sub-Saharan Africa countries.

Reopening Schools After a Novel Coronavirus Surge.

The coronavirus disease 2019 (COVID-19) pandemic shook the world in ways not seen since the pandemic influenza of 1918-1919. As of late August 2020, over 25 million persons had been infected, and we will see the global death toll exceed one million by the end of 2020. Both are minimum estimates. All segments of society have been drastically affected. Schools worldwide have been forced to close due to illness and absenteeism, transmission and risk to vulnerable members of the school community, and community concerns. The decision to reopen school during a pandemic will have a tremendous impact on children's safety, growth, and well-being. Not opening invites social isolation and suboptimal educational experiences, especially for youth whose computing assets and online access are limited and those with special needs. The opening has hazards as well, and the mitigation of these risks is the topic of this chapter. Opening schools requires careful considerations of benefits, risks, and precautions. Guiding principles for safety and strategic application of the principles in each educational niche are critical issues to consider during school reopening. The fundamental principles of disease control involve school-directed initiatives (physical distancing and mask use, hand/face and surface cleansing, administrative controls, engineering controls) and individual-level risk reduction approaches to maximize adherence to new guidelines. The school-initiated "top-down" approaches and the individual-level "bottom-up" approaches must be synergized, as no single method will ensure safety. We discuss how to effectively layer strategies in each educational space to increase safety. Since the vulnerability of children has been heightened during this pandemic crisis, we highlight the special considerations for mental health support that should be considered by schools. The safety principles, disease control strategies, and other critical issues discussed here will serve as a starting point for developing a safe, comprehensive, and feasible reopening plan.