Stability analysis of SEIR model related to efficiency of vaccines for COVID-19 situation

Wintachai, Phitchayapak; Prathom, Kiattisak

doi:10.1016/j.heliyon.2021.e06812

Cited by 51 publications

(34 citation statements)

References 41 publications

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“…Closely related to the above issue is the unresolved question regarding the effect of vaccination in reducing deaths from the disease. Since many countries introduced wholesale vaccination programmes very soon after the adoption of the first internationally certified vaccines and upon the first deliveries of the vaccine itself, one would assume that vaccination has a direct impact on both the number of infected and the number of deaths (Wintachaia and Prathomb 2021). As the data for Slovenia show, the number of infected remained high despite the increasing share of vaccinated people.…”

Section: How To Proceed With the Analysis And Which Data To Includementioning

confidence: 99%

COVID-19 and excess mortality: Was it possible to lower the number of deaths in Slovenia?

Josipovič

2021

STANOVNISHTVO

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This paper presents new data on the age structure of hospitalised SARI (severe acute respiratory infection) patients, with or without COVID-19, broken down by gender, place of infection, and region. The leading hypothesis that COVID-19 deaths are overestimated despite the high share of excess deaths was confirmed, bringing to light the important issue of the demographic breakdown of the population at risk. Thus, the main reason for the decreasing number of COVID-19 deaths is to be sought within the exhausted demographic pool of the elderly population in 2020, when the mortality rate was 19% higher compared to the previous five-year period (2015-2019). Demographic disparities across regions are immense and statistically explain the differences in the ?infected versus deceased? ratio. The excess mortality in 2020 was unusually high, but the projected value for 2020 based on the mortality pattern across age groups from 2015 to 2019 contributed up to one-third of the surplus. So, for one-quarter of alleged COVID-19 deaths (roughly 600 out of some 3,300 in 2020), death was expected to take place in 2020 anyway.

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Section: How To Proceed With the Analysis And Which Data To Includementioning

confidence: 99%

COVID-19 and excess mortality: Was it possible to lower the number of deaths in Slovenia?

Josipovič

2021

STANOVNISHTVO

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“…Most of these studies have consistently demonstrated that effective vaccination would significantly reduce new infections and among the infected, the clinical adversities, ICU admissions and mortality (24)(25)(26). Studies also indicated that a population vaccination coverage of at least 50-80% is required to reduce the effective reproductive number to below one and enables restoration of social activities to a pre-pandemic level (27,28). Some studies have evaluated the transmission of hypothetical SARS-CoV-2 variants before the actual report of B.1.1.7 in the US (29,30).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the Impact of SARS-CoV-2 Variants on the COVID-19 Epidemic and Social Restoration in the United States: A Mathematical Modelling Study

Zou

et al. 2022

Front. Public Health

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Background: Multiple SARS-CoV-2 variants are still rampant across the United States (US). We aimed to evaluate the impact of vaccination scale-up and potential reduction in the vaccination effectiveness on the COVID-19 epidemic and social restoration in the US.Methods: We extended a published compartmental model and calibrated the model to the latest US COVID-19 data. We estimated the vaccine effectiveness against the variant and evaluated the impact of a potential reduction in vaccine effectiveness on the epidemics. We explored the epidemic trends under different levels of social restoration.Results: We estimated the overall existing vaccine effectiveness against the variant as 88.5% (95% CI: 87.4–89.5%) with the vaccination coverage of 70% by the end of August, 2021. With this vaccine effectiveness and coverage, there would be 498,972 (109,998–885,947) cumulative infections and 15,443 (3,828–27,057) deaths nationwide over the next 12 months, of which 95.0% infections and 93.3% deaths were caused by the variant. Complete social restoration at 60, 65, 70% vaccination coverage would increase cumulative infections to 1.6 (0.2–2.9) million 0.7 (0.1–1.2) million, and 511,159 (110,578–911,740), respectively. At same time it would increase cumulative deaths to 39,040 (5,509–72,570), 19,562 (3,873–35,250), 15,739 (3,841–27,638), respectively. However, if the vaccine effectiveness were reduced to 75%, 50% or 25% due to new SARS-CoV-2 variants, there would be 667,075 (130,682–1,203,468), 1.7 (0.2–3.2) million, 19.0 (5.3–32.7) million new infections and 19,249 (4,281–34,217), 42,265 (5,081–79,448), 426,860 (117,229–736,490) cumulative deaths to occur over the next 12 months. Further, social restoration at a lower vaccination coverage would lead to even greater secondary outbreaks.Conclusion: Current COVID-19 vaccines remain effective against the SARS-CoV-2 variant, and 70% vaccination coverage would be sufficient to restore social activities to a pre-pandemic level. Further reduction in vaccine effectiveness against SARS-CoV-2 variants would result in a potential surge of the epidemic. Multiple measures, including public health interventions, vaccination scale-up and development of a new vaccine booster, should be integrated to counter the new challenges of new SARS-CoV-2 variants.

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“…Mathematical models have been used to study many epidemics (including the COVID-19 pandemic) and predict different health outcomes [58][59][60][61][62][63]. The models can be used to investigate the effects of non-pharmaceutical interventions on important aspects without the need for making forecasts, which is a more complex issue.…”

Section: Introductionmentioning

confidence: 99%

Mathematical Modeling to Study Optimal Allocation of Vaccines against COVID-19 Using an Age-Structured Population

González-Parra

Cogollo

Arenas

2022

Axioms

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Vaccination against the coronavirus disease 2019 (COVID-19) started in early December of 2020 in the USA. The efficacy of the vaccines vary depending on the SARS-CoV-2 variant. Some countries have been able to deploy strong vaccination programs, and large proportions of their populations have been fully vaccinated. In other countries, low proportions of their populations have been vaccinated, due to different factors. For instance, countries such as Afghanistan, Cameroon, Ghana, Haiti and Syria have less than 10% of their populations fully vaccinated at this time. Implementing an optimal vaccination program is a very complex process due to a variety of variables that affect the programs. Besides, science, policy and ethics are all involved in the determination of the main objectives of the vaccination program. We present two nonlinear mathematical models that allow us to gain insight into the optimal vaccination strategy under different situations, taking into account the case fatality rate and age-structure of the population. We study scenarios with different availabilities and efficacies of the vaccines. The results of this study show that for most scenarios, the optimal allocation of vaccines is to first give the doses to people in the 55+ age group. However, in some situations the optimal strategy is to first allocate vaccines to the 15–54 age group. This situation occurs whenever the SARS-CoV-2 transmission rate is relatively high and the people in the 55+ age group have a transmission rate 50% or less that of those in the 15–54 age group. This study and similar ones can provide scientific recommendations for countries where the proportion of vaccinated individuals is relatively small or for future pandemics.

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Stability analysis of SEIR model related to efficiency of vaccines for COVID-19 situation

Cited by 51 publications

References 41 publications

COVID-19 and excess mortality: Was it possible to lower the number of deaths in Slovenia?

COVID-19 and excess mortality: Was it possible to lower the number of deaths in Slovenia?

Evaluating the Impact of SARS-CoV-2 Variants on the COVID-19 Epidemic and Social Restoration in the United States: A Mathematical Modelling Study

Mathematical Modeling to Study Optimal Allocation of Vaccines against COVID-19 Using an Age-Structured Population

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