Are the SIR and SEIR models suitable to estimate the basic reproduction number for the CoViD-19 epidemic?

Yang, Hyun Mo; Lombardi, Luís Pedro; Yang, Ariana Campos

doi:10.1101/2020.10.11.20210831

Cited by 10 publications

(10 citation statements)

References 17 publications

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“…Moreover, the estimated Ω and Π curves showed the epidemic's main characteristic -The sigmoid-shaped curve. This pattern permitted us to observe a second sigmoid curve and analyze the model according to the properties carried on by this curve -The quick increase in the epidemic is associated with a higher risk of infection, which is associated with a higher R 0 [10]. From Figure 2, the epidemic in the second sigmoid increased faster than that observed in the first sigmoid.…”

Section: Discussionmentioning

confidence: 93%

“…Figure 2 shows two sequential sigmoid-shaped Π and Ω curves. In the sigmoid curve, the upward concavity is changed to downward concavity at the inflection point (time) [10] before reaching the plateaux. This behavior corresponds to the variation in the effective reproduction number R ef -In the upward concavity, we have R ef > 1, R ef = 1 at the inflection time, and R ef < 1 in the downward concavity.…”

Section: Phases 3 Andmentioning

confidence: 99%

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Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in São Paulo State (Brazil)

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et al. 2021

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Background: The continuous SARS-CoV-2 transmission in several countries could contribute to the mutations' appearance. The circulation of more virulent variants may increase the number of severe CoViD-19 needing hospital care and fatalities hugely. Methods: The partial quarantine in São Paulo State and further relaxation associated with the mutations are explained by a mathematical model based on the CoViD-19 natural history encompassing the age-dependent fatality. The model parameters were fitted considering the observed data from São Paulo State. Results: The partial quarantine was explained by the less virulent SARS-CoV-2 transmission, but the relaxation alone could not explain the epidemic observed in São Paulo State. However, more virulent variants plus the transmission among isolated individuals explained the increased CoViD-19 fatalities. Conclusions: The model described the CoViD-19 epidemic in São Paulo State by considering the partial quarantine, relaxation and mutations. The model provided a potential epidemiological scenario in the absence of mass vaccination.

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Section: Discussionmentioning

confidence: 93%

Section: Phases 3 Andmentioning

confidence: 99%

Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in São Paulo State (Brazil)

Hm¹,

Lpp

Ffm

et al. 2021

Preprint

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“…However, the available data at the beginning of the epidemic is the severe CoViD-19 cases, which are hospitalized and, probably, they are not transmitting except to the hospital staff. Hence, the SEIR model is not appropriate to describe the CoViD-19 epidemic [9].…”

Section: Reliable Estimation Of Rmentioning

confidence: 99%

“…They estimated the effective reproduction number R ef around 2.4. In the SEIR model, the severe CoViD-19 cases were used to estimate the basic reproduction number R 0 ; however, those individuals are isolated in hospitals receiving treatment [9].…”

Section: Introductionmentioning

confidence: 99%

Mathematical modeling of the transmission of SARS-CoV-2—Evaluating the impact of isolation in São Paulo State (Brazil) and lockdown in Spain associated with protective measures on the epidemic of CoViD-19

et al. 2021

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Coronavirus disease 2019 (CoViD-19), with the fatality rate in elder (60 years old or more) being much higher than young (60 years old or less) patients, was declared a pandemic by the World Health Organization on March 11, 2020. A mathematical model considering young and elder subpopulations under different fatality rates was formulated based on the natural history of CoViD-19 to study the transmission of the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The model considered susceptible, exposed, asymptomatic, pre-symptomatic, mild CoViD-19, severe CoViD-19, and recovered compartments, besides compartments of isolated individuals and those who were caught by test. This model was applied to study the epidemiological scenario resulting from the adoption of quarantine (isolation or lockdown) in many countries to control the rapid propagation of CoViD-19. We chose as examples the isolation adopted in São Paulo State (Brazil) in the early phase but not at the beginning of the epidemic, and the lockdown implemented in Spain when the number of severe CoViD-19 cases was increasing rapidly. Based on the data collected from São Paulo State and Spain, the model parameters were evaluated, and we obtained a higher estimation for the basic reproduction number R0 (9.24 for São Paulo State, and 8 for Spain) compared to the currently accepted estimation of R0 around 2 using the SEIR (susceptible, exposed, infectious, and recovered compartments) model. In comparison with the lockdown in Spain, the relatively early adoption of the isolation in São Paulo State resulted in enlarging the period of the first wave of the epidemic and delaying its peak. The model allowed to explain the flattening of the epidemic curves by quarantine when associated with the protective measures (face mask, washing hands with alcohol and gel, and social distancing) adopted by the population. The description of the epidemic under quarantine and protections can be a background to foreseen the epidemiological scenarios from the release strategies, which can help guide public health policies by decision-makers.

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“…That model assumed that asymptomatic, pre-symptomatic, and mild COVID-19 individuals transmit SARS-CoV-2, while severe COVID-19 cases are isolated in hospitals. It is worth stressing that the SEIR-type (susceptible, exposed, infectious, and recovered compartments) models estimate the transmission rate using the severe COVID-19 registered cases as SARS-CoV-2 transmitters (Yang et al 2020a). That model was applied to evaluate the impacts on the COVID-19 epidemic by partial quarantine in São Paulo State and rigid quarantine (lockdown) in Spain associated with the protective measures (washing hands with alcohol and gel, use of face mask, and social distancing).…”

Section: Introductionmentioning

confidence: 99%

Evaluating the impacts of relaxation and mutation in the SARS-CoV-2 on the COVID-19 epidemic based on a mathematical model: a case study of São Paulo State (Brazil)

et al. 2021

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At the beginning of 2020, SARS-CoV-2 spread to all continents, and many countries adopted quarantine to flatten the COVID-19 outbreak, resulting in the containment of transmission. However, the persistent transmission of SARS-CoV-2, an RNA virus, resulted in the appearance of mutations in the original virus. The appearance of more virulent mutations in different regions of the world resulted in an increased number of severe COVID-19 cases. A mathematical model based on the COVID-19 natural history encompassing the mutations was applied to evaluate the SARS-CoV-2 epidemic. The model parameters were fitted against the observed data from São Paulo State (Brazil) considering quarantine, relaxation, and mutation. The estimated data from São Paulo State showed that the original SARS-CoV-2 transmission better explained the COVID-19 epidemic during the quarantine. However, the increased number of fatalities beyond that predicted by the relaxation indicated the occurrence of mutations. Hence, the relaxation in association with the transmission of a more virulent SARS-CoV-2 better estimated the COVID-19 epidemic from February 26, 2020, to June 15, 2021

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Are the SIR and SEIR models suitable to estimate the basic reproduction number for the CoViD-19 epidemic?

Cited by 10 publications

References 17 publications

Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in São Paulo State (Brazil)

Quarantine, relaxation and mutation explaining the CoViD-19 epidemic in São Paulo State (Brazil)

Mathematical modeling of the transmission of SARS-CoV-2—Evaluating the impact of isolation in São Paulo State (Brazil) and lockdown in Spain associated with protective measures on the epidemic of CoViD-19

Evaluating the impacts of relaxation and mutation in the SARS-CoV-2 on the COVID-19 epidemic based on a mathematical model: a case study of São Paulo State (Brazil)

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