Estimation of the probability of reinfection with COVID-19 coronavirus by the SEIRUS model

Reproductive Number ◽

Chain Reaction ◽

Health Community ◽

Polymerase Chain ◽

Model Equations ◽

Disease Free ◽

AbstractWith sensitivity of the Polymerase Chain Reaction (PCR) test used to detect the presence of the virus in the human host, the global health community has been able to record a great number of recovered population. Therefore, in a bid to answer a burning question of reinfection in the recovered class, the model equations which exhibits the disease-free equilibrium (E0) state for COVID-19 coronavirus was developed in this study and was discovered to both exist as well as satisfy the criteria for a locally or globally asymptotic stability with a basic reproductive number R0 = 0 for and endemic situation. Hence, there is a chance of no secondary reinfections from the recovered population as the rate of incidence of the recovered population vanishes, that is, B = 0.Furthermore, numerical simulations were carried to complement the analytical results in investigating the effect of the implementation of quarantine and observatory procedures has on the projection of the further spread of the virus globally. Result shows that the proportion of infected population in the absence of curative vaccination will continue to grow globally meanwhile the recovery rate will continue slowly which therefore means that the ratio of infection to recovery rate will determine the death rate that is recorded globally and most significant for this study is the rate of reinfection by the recovered population which will decline to zero over time as the virus is cleared clinically from the system of the recovered class.

Estimation of the Probability of Reinfection With COVID-19 by the Susceptible-Exposed-Infectious-Removed-Undetectable-Susceptible Model (Preprint)

10.2196/preprints.19097 ◽

2020 ◽

Cited By ~ 1

Author(s):

Alexander Victor Okhuese

Keyword(s):

Recovery Rate ◽

Polymerase Chain Reaction Test ◽

Reproductive Number ◽

Health Community ◽

Existence And Stability ◽

Polymerase Chain ◽

Model Equations ◽

Chain Reaction Test ◽

BACKGROUND With the sensitivity of the polymerase chain reaction test used to detect the presence of the virus in the human host, the worldwide health community has been able to record a large number of the recovered population. OBJECTIVE The aim of this study was to evaluate the probability of reinfection in the recovered class and the model equations, which exhibits the disease-free equilibrium state for the coronavirus disease. METHODS The model differential equation was evaluated for the disease-free equilibrium for the case of reinfection as well as the existence and stability criteria for the disease, using the model proportions. This evaluation shows that the criteria for a local or worldwide asymptotic stability with a basic reproductive number (R0=0) were satisfied. Hence, there is a chance of no secondary reinfections from the recovered population, as the rate of incidence of the recovered population vanishes (ie, B=0). RESULTS With a total of about 900,000 infected cases worldwide, numerical simulations for this study were carried out to complement the analytical results and investigate the effect that the implementation of quarantine and observation procedures has on the projection of further virus spread. CONCLUSIONS As shown by the results, the proportion of the infected population, in the absence of a curative vaccination, will continue to grow worldwide; meanwhile, the recovery rate will continue slowly, which means that the ratio of infection rate to recovery rate will determine the death rate that is recorded. Most significant for this study is the rate of reinfection by the recovered population, which will decline to zero over time as the virus is cleared clinically from the system of the recovered class.

Estimation of the Probability of Reinfection With COVID-19 by the Susceptible-Exposed-Infectious-Removed-Undetectable-Susceptible Model

JMIR Public Health and Surveillance ◽

10.2196/19097 ◽

2020 ◽

Vol 6 (2) ◽

pp. e19097 ◽

Cited By ~ 12

Author(s):

Alexander Victor Okhuese

Keyword(s):

Recovery Rate ◽

Polymerase Chain Reaction Test ◽

Reproductive Number ◽

Health Community ◽

Existence And Stability ◽

Polymerase Chain ◽

Model Equations ◽

Chain Reaction Test ◽

Background With the sensitivity of the polymerase chain reaction test used to detect the presence of the virus in the human host, the worldwide health community has been able to record a large number of the recovered population. Objective The aim of this study was to evaluate the probability of reinfection in the recovered class and the model equations, which exhibits the disease-free equilibrium state for the coronavirus disease. Methods The model differential equation was evaluated for the disease-free equilibrium for the case of reinfection as well as the existence and stability criteria for the disease, using the model proportions. This evaluation shows that the criteria for a local or worldwide asymptotic stability with a basic reproductive number (R0=0) were satisfied. Hence, there is a chance of no secondary reinfections from the recovered population, as the rate of incidence of the recovered population vanishes (ie, B=0). Results With a total of about 900,000 infected cases worldwide, numerical simulations for this study were carried out to complement the analytical results and investigate the effect that the implementation of quarantine and observation procedures has on the projection of further virus spread. Conclusions As shown by the results, the proportion of the infected population, in the absence of a curative vaccination, will continue to grow worldwide; meanwhile, the recovery rate will continue slowly, which means that the ratio of infection rate to recovery rate will determine the death rate that is recorded. Most significant for this study is the rate of reinfection by the recovered population, which will decline to zero over time as the virus is cleared clinically from the system of the recovered class.

Assessing Sex Differential in COVID-19 Mortality Rate by Age and Polymerase Chain Reaction Test Results; An Iranian Multi-Center Study

10.21203/rs.3.rs-309181/v1 ◽

2021 ◽

Author(s):

Mehdi Azizmohammad Looha ◽

Mostafa Rezaei-Tavirani ◽

Mohammad Rostami-Nejad ◽

Shahriar Janbazi ◽

Elaheh Zarean ◽

...

Keyword(s):

Mortality Rate ◽

Differential Effect ◽

Death Rate ◽

Age Groups ◽

Test Results ◽

Chain Reaction ◽

Negative Test ◽

Polymerase Chain ◽

Abstract Background: Males are more likely to die from COVID-19 than females. In addition, the mortality rate among positive and suspected COVID-19 patients were reported in many literatures. The aim of this study is to evaluate the sex differential effect in the COVID-19 mortality by different age groups and polymerase chain reaction (PCR) test results. Methods: in a multicenter cross-sectional study from 55 hospitals in Tehran, Iran, patients were categorized as the positive, negative and suspected cases. Age group, sex and hospital wards were also assessed in analysis. Results: A total of 25481 cases (14791 males) were included in the study with the mortality rate of 12.0%. The mortality rate in positive, negative and suspected cases were 20.55%, 9.97% and 7.31%, respectively. Although the mortality in negative test group was considerable, sex was not associated with the death rate in this group. Using Cox regression model, sex had a significant effect on the hazard of death due to COVID-19 in adults and senior patients having positive and suspected PCR test results. However, sex was not found as significant factor for mortality in patients with negative PCR test occurring to different age groups. Conclusion: Regardless of other risk factors, we found that sex differential effect in COVID-19 mortality varies significantly in different age groups; therefore, appropriate strategies should be designed to protect adult and senior men from this deadly infectious disease. Furthermore, owing to the considerable death rate of COVID-19 patients with negative test results, new policies should be launched increase the accuracy of diagnosis tests.

An SEIRS Epidemic Model with Immigration and Vertical Transmission

Asian Research Journal of Mathematics ◽

10.9734/arjom/2020/v16i1130241 ◽

2020 ◽

pp. 48-53

Author(s):

Ruksana Shaikh ◽

Pradeep Porwal ◽

V. K. Gupta

Keyword(s):

Vertical Transmission ◽

Epidemic Model ◽

Equilibrium Points ◽

Reproductive Number ◽

Asymptotically Stable ◽

Seirs Epidemic Model ◽

Model Equations ◽

The Stability ◽

The study indicates that we should improve the model by introducing the immigration rate in the model to control the spread of disease. An SEIRS epidemic model with Immigration and Vertical Transmission and analyzed the steady state and stability of the equilibrium points. The model equations were solved analytically. The stability of the both equilibrium are proved by Routh-Hurwitz criteria. We see that if the basic reproductive number R0<1 then the disease free equilibrium is locally asymptotically stable and if R0<1 the endemic equilibrium will be locally asymptotically stable.

Mathematical Predictions for Covid-19 as a Global Pandemic (Preprint)

10.2196/preprints.19166 ◽

2020 ◽

Cited By ~ 2

Author(s):

Alexander Okhuese Victor

Keyword(s):

Recovery Rate ◽

Reproductive Number ◽

Policy Makers ◽

Infected Population ◽

Global Pandemic ◽

Secondary Infections ◽

Rate Of Recovery ◽

Precautionary Measures ◽

Model Equations

UNSTRUCTURED The model equations which exhibits the disease-free equilibrium (E_0 ) state for COVID-19 coronavirus does not exist and hence does not satisfy the criteria for a locally or globally asymptotic stability when the basic reproductive number R_0=1 for and endemic situation. This implies that the COVID-19 coronavirus does not have a curative vaccine yet and precautionary measures are advised through quarantine and observatory procedures. The basic reproductive number was found to be R_0<1 and hence shows that there is a chance of decline of secondary infections when the ratio between the incidence rate in the population and the total number of infected population quarantined with observatory procedure. Furthermore, numerical simulations were carried to complement the analytical results in investigating the effect of the implementation of quarantine and observatory procedures has on the projection of the further spread of the virus globally. Result shows that the proportion of infected population in the absence of curative vaccination will continue to grow globally meanwhile the recovery rate will continue slowly which therefore means that the ratio of infection to recovery rate will determine the death rate that is recorded globally. Therefore, the effort to evaluate the disease equilibrium shows that unless there is a dedicated effort from individual population, government, health organizations, policy makers and stakeholders, the world would hardly be reed of the COVID-19 coronavirus and further spread is eminent and the rate of infection will continue to increase despite the increased rate of recovery until a curative vaccine is developed.

Death and COVID-19 Anxiety in Home-Quarantined Individuals Aged 65 and Over During the Pandemic

OMEGA - Journal of Death and Dying ◽

10.1177/00302228211059894 ◽

2021 ◽

pp. 003022282110598

Author(s):

Hümeyra Aslaner ◽

Betül Özen ◽

Zeliha K. Erten ◽

Mebrure Beyza Gökçek

Keyword(s):

Death Anxiety ◽

Short Form ◽

Anxiety Score ◽

Test Results ◽

Rt Pcr ◽

Chain Reaction ◽

Polymerase Chain ◽

Test Result ◽

Urgent measures were taken for those at the age of 65 and over who were at the risk group all over the world due to the COVID-19 pandemic. It is known that many individuals at the age of 65 and over have experienced anxiety due to the uncertainties. This study aimed to determine the anxiety and death anxiety in individuals aged 65 and over who were isolation at home due to being diagnosed with COVID-19 or being in contact during the pandemic process. The study is descriptive and cross-sectional. It was performed with 656 home-quarantined individuals aged between 65–80 years with positive or negative real-time polymerase chain reaction (RT-PCR) test result. A form including questions about the death anxiety and the Coronavirus Anxiety Scale Short Form prepared by the researchers were administered to the individuals by phone call. Of the participants, 49.5% were male. Median COVID-19 anxiety score was 4 (0–18). Anxiety scores of the male and female participants were similar. Participants with negative polymerase chain reaction (PCR) results and those with death anxiety had higher COVID anxiety scores. Death anxiety has increased by 1.661 times in male gender, 1.983 times in RT-PCR positivity and 0.146 times in the presence of symptoms. Individuals with positive COVID-19 test results or those aged 65 and over who had death anxiety and negative COVID-19 test result but who were in home-isolation due to being a contact had higher anxiety score. For this reason, those with death anxiety can be supported in line with their religious beliefs to reduce anxiety. Those with negative PCR test results in quarantine can be adequately informed about the COVID-19.

Mathematical Analysis and Stochastic Stability of Nonlinear Epidemic Model with Incidence Rate

Asian Research Journal of Mathematics ◽

10.9734/arjom/2020/v16i730199 ◽

2020 ◽

pp. 8-19

Author(s):

Laid Chahrazed

Keyword(s):

Incidence Rate ◽

Epidemic Model ◽

Reproductive Number ◽

Globally Asymptotically Stable ◽

Saturated Incidence Rate ◽

Saturated Incidence ◽

The Stability ◽

Disease Free ◽

Temporary Immunity

In this work, we consider a nonlinear epidemic model with temporary immunity and saturated incidence rate. Size N(t) at time t, is divided into three sub classes, with N(t)=S(t)+I(t)+Q(t); where S(t), I(t) and Q(t) denote the sizes of the population susceptible to disease, infectious and quarantine members with the possibility of infection through temporary immunity, respectively. We have made the following contributions: The local stabilities of the infection-free equilibrium and endemic equilibrium are; analyzed, respectively. The stability of a disease-free equilibrium and the existence of other nontrivial equilibria can be determine by the ratio called the basic reproductive number, This paper study the reduce model with replace S with N, which does not have non-trivial periodic orbits with conditions. The endemic -disease point is globally asymptotically stable if R0 ˃1; and study some proprieties of equilibrium with theorems under some conditions. Finally the stochastic stabilities with the proof of some theorems. In this work, we have used the different references cited in different studies and especially the writing of the non-linear epidemic mathematical model with [1-7]. We have used the other references for the study the different stability and other sections with [8-26]; and sometimes the previous references.

Streptococcus agalactiae mastitis of bovine detection by Polymerase Chain Reaction (PCR) test in AL-Diwanyia province

Al-Qadisiyah Journal of Veterinary Medicine Sciences ◽

10.29079/vol12iss2art263 ◽

2013 ◽

Vol 12 (2) ◽

pp. 101

Author(s):

Gh. K. A. Al-kuzaay ◽

Q. H. Kshash

Keyword(s):

Streptococcus Agalactiae ◽

Specific Primer ◽

Chain Reaction ◽

Pcr Assay ◽

Milk Samples ◽

Bacteriological Testing ◽

Polymerase Chain ◽

This study was conducted for exam 348 milk samples from (clinically mastitic and other healthy cows) in many areas in AL-Diwanyia province by using CMT and bacteriological testing , which appeared that (64.9%) as percentage of mastitis ( clinically 15.9% , subclinically 84.0% ) Streptococcus agalactiae mastitis 13.2% ( 26.6% clinically , 73.3 % subclinicaly) diagnose by PCR assay by using specific primer (16SrRNA). Streptococcus agalactiae (30 isolates) after classical methods applied for streptococcus agalactiae identification (86 isolates).

TRANSMISSION DYNAMICS OF DENGUE IN COSTA RICA: THE ROLE OF HOSPITALIZATIONS

Revista de Matemática Teoría y Aplicaciones ◽

10.15517/rmta.v27i1.39977 ◽

2019 ◽

Vol 27 (1) ◽

pp. 241-266

Author(s):

FABIO SANCHEZ ◽

JORGE ARROYO-ESQUIVEL ◽

PAOLA VÁSQUEZ

Keyword(s):

Costa Rica ◽

Compartmental Model ◽

Control Strategies ◽

Transmission Dynamics ◽

Reproductive Number ◽

Specific Parameter ◽

Public Health Officials ◽

For decades, dengue virus has caused major problems for public health officials in tropical and subtropical countries around the world. We construct a compartmental model that includes the role of hospitalized individuals in the transmission dynamics of dengue in Costa Rica. The basic reproductive number, R0, is computed, as well as a sensitivity analysis on R0 parameters. The global stability of the disease-free equilibrium is established. Numerical simulations under specific parameter scenarios are performed to determine optimal prevention/control strategies.

Evaluating the bacterial culture technique by Polymerase chain reaction for the diagnosis of Brucella abortus in milk of cows suspected with brucellosis.

The Iraqi Journal of Veterinary Medicine ◽

10.30539/iraqijvm.v40i1.130 ◽

2016 ◽

Vol 40 (1) ◽

pp. 5-8

Author(s):

Bashar Sadeq Noomy

Keyword(s):

Brucella Abortus ◽

Bacterial Culture ◽

Culture Technique ◽

Test Results ◽

Chain Reaction ◽

Culture Techniques ◽

Milk Samples ◽

Polymerase Chain ◽

The aim of this study is to determine the sensitivity of bacterial culture technique in the detection of Brucella abortus in milk samples of aborted cows. Sixty samples of milk were collected from aborted cows during a period which did not exceed two months after the abortion. All of them were positive for rose bengal test. Results showed that Brucella abortus was isolated from 7 out of 60 (11.6%) from the milk of aborted cows, while PCR test showed that 32 out of 60 (53.3%) milk sample contained Brucella abortus. The specificity of culture techniques was 10%, but its sensitivity was only 21.8%. Beside the cautions in dealing with live Brucella abortus (as culture), it is also less sensitive than PCR, though it is better to use PCR technique in the diagnosis of brucellosis in aborted cows milk.