Covid-19 disease dynamics with vaccination: The effect of uncertainty

Rate parameters are critical in estimating the covid burden using mathematical models. In the Covid-19 mathematical models, these parameters are assumed to be constant. However, uncertainties in these rate parameters are almost inevitable. In this paper, we study a stochastic epidemic model of the SARS-CoV-2 virus infection in the presence of vaccination in which some parameters fluctuate around its average value. Our analysis shows that if the stochastic basic reproduction number (SBRN) of the system is greater than unity, then there is a stationary distribution, implying the long-time disease persistence. A sufficient condition for disease eradication is also prescribed for which the exposed class goes extinct, followed by the infected class. The disease eradication criterion may not hold if the rate of vaccine-induced immunity loss increases or/and the force of infection increases. Using the Indian Covid-19 data, we estimated the model parameters and showed the future disease progression in the presence of vaccination. The disease extinction time is estimated under various conditions. It is revealed that the mean extinction time is an increasing function of both the force of infection and immunity loss rate and shows the lognormal distribution. We point out that disease eradication might not be possible even at a higher vaccination rate if the vaccine-induced immunity loss rate is high. Our observation thus indicates the endemicity of the disease for the existing vaccine efficacy. The disease eradication is possible only with a higher vaccine efficacy or a reduced infection rate.

The Impact of Vaccination on Covid-19 Disease Transmission Patterns in a Human Population: A Theoretical Analysis

We construct a Mathematical model that describes the effect of vaccination on the dynamics of the transmission of COVID-19 disease in a human population. The model is a system of ordinary differential equations that describes the evolution of humans in a range of Covid-19 states due to emergence of an index case in a disease free region. The analysis of the model shows that effective vaccination can lead to disease eradication, where in the disease free state is locally asymptomatically stable if the basic reproductive number, and unstable when The numerical simulations suggests the use of other social measures alongside vaccination in order to avert the possibility of the disease becoming endemic.

Communicable Disease

This chapter examines the idea of contagion—of risk magnification and modulation through networks. The chapter examines three case studies, each of which raises different questions about the interplay of causal complexity, performativity, and policymaking: vaccination policy, drug resistant infections, and disease eradication. In vaccination policy, achieving herd immunity is often crucial, but attempts to do this are heavily dependent on public trust. Drug resistant infections arise, among other causes, through the inevitable impact of natural selection, and so require a shift towards an ecological perspective on disease. Finally, the possibility of disease eradication poses important questions about when and how to ensure that susceptible health threats are systematically and permanently removed from the environment.

Emergence of African Swine Fever in Poland (2014–2021). Successes and Failures in Disease Eradication

African swine fever (ASF) in Poland has been a major concern for pig production for the last seven years. The main constrains in ASF eradication in Poland are due to the high density of wild boar in ASF-affected areas of the country. Other factors, responsible for long-distance ASF spread to new regions of the country, are mainly related to human-mediated activity and lack of awareness of the potential disease threat to pig production. In the case of pig holdings, the only effective measure of ASF prevention is strict implementation of biosecurity rules. Despite many efforts to implement these measures, the disease occurred in a number of voivodeships, poviats and counties of Poland, primarily in eastern Poland; however, starting from 2019, also in the western part of the country. Further recommendations to eradicate ASF in Poland or at least to minimize the economic loss caused by ASF in pig production include effective wild boar population management strategies along with the implementation of strict biosecurity measures. The observations from the last seven years of ASF epizootic in Poland clearly indicate that the disease could not have been effectively controlled in wild boar population and could only be restricted in domestic pig population following severe biosecurity rules. As for ASF spread control in wild boar population, the measures applied in other EU countries include active wild boar carcass search and disposal along with sanitary and reduction hunting. These measures have also been shown non-effective. The only solution for future sustainable pig production in Poland seems to be strict collaboration between pig producers, veterinary inspection, and hunting associations.

Dynamical features of pine wilt disease through stability, sensitivity and optimal control

This work investigates the dissemination mechanism of pine wilt disease. The basic reproduction number is computed explicitly, and an ultimate invariable level of contagious hosts and vectors, without and with disease, is discussed by using this number. Highly effective techniques, Lyapunov functional and graph theoretic, are utilised to obtain the ultimate constant level of the whole population. The idea of complete disease eradication and reduction of endemic level is explored through the utilisation of two efficient methods. Using sensitivity analysis approach, necessary control measures are suggested to overcome the disease. Using the literature data, the robustness of control strategies is shown graphically.

Virus Eradication and Synthetic Biology: Changes with SARS-CoV-2?

The eradication of infectious diseases has been achieved only once in history, in 1980, with smallpox. Since 1988, significant effort has been made to eliminate poliomyelitis viruses, but eradication is still just out of reach. As the goal of viral disease eradication approaches, the ability to recreate historically eradicated viruses using synthetic biology has the potential to jeopardize the long-term sustainability of eradication. However, the emergence of the severe acute respiratory syndrome-coronavirus (SARS-CoV)-2 pandemic has highlighted our ability to swiftly and resolutely respond to a potential outbreak. This virus has been synthetized faster than any other in the past and is resulting in vaccines before most attenuated candidates reach clinical trials. Here, synthetic biology has the opportunity to demonstrate its truest potential to the public and solidify a footing in the world of vaccines.

Rethinking disease eradication: putting countries first

There have been various infectious disease eradication programs implemented in various parts of the world with varying degrees of success since the early 1900s. Of all those programs, the one that achieved monumental success was the Smallpox Eradication Program (SEP). Most of the global health leaders and authorities that came up with the new idea of disease eradication in the 1980s tried to design and shape the new programs based on their experience in the SEP. The SEP had a very effective tool, vaccine, that did not require a cold chain system, and a relatively simple way of administration. The total cost of the eradication program was about US$300 million and the entire campaign took about 10 y. However, the Guinea worm and polio eradication programs that followed in the footsteps of SEP attained varying levels of success, consuming a huge amount of resources and taking a much longer time (>30 y each). This paper reviews the factors that played major roles in hindering the attainment of eradication goals and outlines possible recommendations for the way forward. Among other things, this paper strongly emphasizes that endemic countries should take the lead in all matters pertaining to making decisions for disease elimination and/or eradication initiatives and that ‘elimination as a public health problem’ is the preferred option rather than going for complete eradication at the expense of other health programs and thereby contributing to weakening of already fragile health systems, mainly in Africa.