Could obesity be a risk factor for adverse clinical outcomes of COVID-19? Review article

Aims: This narrative review’s purpose was to verify a possible association between obesity and COVID-19-related outcomes. Methods: A PubMed research was done in May 2020, and after the eligibility criteria, 10 articles were included, which were analyzed, and its results compared. Results: It was observed that, because of the changes caused by obesity in the organism, this comorbidity is an important risk factor for Sars-CoV-2’s infection severity and hospital stay. Moreover, obesity has been considered a risk factor for adverse clinical outcomes. Also, it was possible to notice that most individuals with obesity were male, therefore a direct relation was traced between men with obesity and COVID-19’s severity, and this population required more intubation and those older than 20 years old presented higher mortality rate. Besides that, the association between obesity and other comorbidities seems to worsen even more the infectious state. Conclusions: However, it was not possible to find a pathophysiological mechanism that can fully explain those associations. Therefore, more studies are vital to understand this subject.

Modifying the network-based stochastic SEIR model to account for quarantine: an application to COVID-19

Objectives: Diseases such as SARS-CoV-2 have novel features that require modifications to the standard network-based stochastic SEIR model. In particular, we introduce modifications to this model to account for the potential changes in behavior patterns of individuals upon becoming symptomatic, as well as the tendency of a substantial proportion of those infected to remain asymptomatic. Methods: Using a generic network model where every potential contact exists with the same common probability, we conduct a simulation study in which we vary four key model parameters (transmission rate, probability of remaining asymptomatic, and the mean lengths of time spent in the exposed and infectious disease states) and examine the resulting impacts on various metrics of epidemic severity, including the effective reproduction number. We then consider the effects of a more complex network model. Results: We find that the mean length of time spent in the infectious state and the transmission rate are the most important model parameters, while the mean length of time spent in the exposed state and the probability of remaining asymptomatic are less important. We also find that the network structure has a significant impact on the dynamics of the disease spread. Conclusions: In this article, we present a modification to the network-based stochastic SEIR epidemic model which allows for modifications to the underlying contact network to account for the effects of quarantine. We also discuss the changes needed to the model to incorporate situations where some proportion of the individuals who are infected remain asymptomatic throughout the course of the disease.

A NUTRITION VIEW OF COVID 19 IN THE PANDEMIC

COVID-19 is a disease caused by a coronavirus, called SARS-CoV-2. This virus has become a major public health concern worldwide, causing a collective outbreak, leading to the pandemic in 2020. People become infected with other common coronaviruses throughout their lives, but currently the concern is the COVID-19 type due to its severity in some cases. The immune system protects the body against external aggressions and preserves the body's homeostasis, and nutrients are involved in the development and preservation of this system. Considering the degree of complications that can occur in an individual with COVID-19, regardless of their age group, and in some cases even lethal, there was an interest in researching studies about this disease, and which nutrients are mentioned in the literature regarding immunity in this disease. The aims of this research were to describe concepts about the disease COVID-19 and to identify nutrients involved in the immunity and treatment of this disease, through a literature review in the period from December 2019 to October 2020. There is no doubt that it is essential to maintain an adequate nutritional status, through a balanced diet that can contribute to a better coping with the infectious state. Supplementation of vitamins, minerals, probiotics and prebiotics can provide the immune system, several of them were cited as an adjunct to the treatment of COVID-19, including their doses, but there was a lack of agreement regarding the dose of nutrients. Obviously maintaining social distance, wearing masks and proper hygiene are essential to reduce the risk of contamination, while not having access to vaccination.

Global Stability of COVID-19 Model: A Case Study of Nepal

COVID-19 (Corona Virus Disease) is continuously spreading all over the world from January 2020. It has been the major public health concern worldwide. In Nepal, the confirmed cases of the dis ease are increasing day by day. Mathematical modeling is one of the best tool to study the transmission dynamics of COVID - 19. In the present work, the transmission dynamics of COVID - 19 in Nepal with isolation is studied by using epidemic compartmental model. The global stability of the equilibrium points of the model are discussed with Lyapunov function. The stability of the disease is dependent on both trans- mission rate of the disease and the progression rate of the infectious state to isolated or hospitalized state. Simulations are made to observe situation of the disease in Nepal using the mathematical results graphically.

Numerical Simulations of a Modified SIR Model Fitting Statistical Datafor COVID19

We consider a system of ordinary differential equations obtained by modifying the classical SIR modelin epidemiology in order to account for the particular features of COVID­19 and the structure of the availablestatistical data. Its main feature is that the infectious state is being split in two different stages. In the first one,which lasts a few days after being infected, the individuals are considered to be contagious and able to spreadfurther the disease. After this, the individuals are considered to be isolated and this second stage lasts until eitherrecovery or death is reported. The parameters of the model are fitted for several countries (Germany, Italy, Spain,Russia, USA, Romania) such that the solution matches the known number of new cases, active cases, recoveriesand deaths. The values of these parameters give insight regarding the evolution of the pandemy and can revealdifferent policies and approaches in reporting the official data. For example one of them can indicate that in certaincountries a substantial amount of cases were reported only post­mortem. The variation across several countries ofanother parameter, which models the average convalescence time (the duration of the second stage of the infectiousstate), points to the fact that the recoveries are reported at different rates, in some cases with significant delays.Since it can be assumed that this is only a matter of reporting, we also perform additional simulations for thesecountries by taking the average convalescence time the value of Germany, which is the smallest within the wholerange. The conclusion is that under this assumption, the evolution of the active cases for example in Italy andSpain, is not significantly different to that in Germany, the comparison being based on the fact that these countriesshowed a similar number of cases within the considered period.

Vaccinating behaviour guided by imitation and aspiration

Vaccinating decisions can be influenced by imitation as well as self-evaluation or aspiration. This work analyses vaccinating behaviours by coupling both imitation and aspiration update rules, adopting an existing set-up of the mean-field vaccination game. We incorporate the imitation mechanism with several variants of the aspiration protocol, encompassing constant and adaptive aspirations. Equations of the combined dynamics have been derived by grouping the population according to (i) vaccinating strategies and (ii) healthy and infected status within each strategy. If aspiration levels are fixed but differentiated by vaccinating strategies, then vaccinators aspiring less than non-vaccinators are found to ameliorate the vaccination coverage, thereby yielding a less infectious state. The adaptive aspirations maintain a positive correlation with the vaccine efficacy while keeping the opposite relation with vaccination cost. When vaccinating strategies, aspirations and update rules are allowed to evolve synchronously, then either the imitation or aspiration process takes over the entire population. If aspiration rules prevail, then vaccinees and non-vaccinees coexist equally (according to (i)) or vaccine uptake follows a non-monotonic trend with the efficacy (according to (ii)). The imitative rule performs better when vaccination is less expensive or cheap, while aspiration updating safeguards the tenacity of vaccinees despite vaccination being expensive.