Projections of the transmission of the Omicron variant for Toronto, Ontario, and Canada using surveillance data following recent changes in testing policies

Yuan, Pei; Aruffo, Elena; Tan, Yi; Yang, Liu; Ogden, Nicholas H.; Fazil, Aamir; Zhu, Huaiping

doi:10.1016/j.idm.2022.03.004

Cited by 17 publications

(21 citation statements)

References 32 publications

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“…Our sensitivity analysis also confirms the importance of compliance of the population for the containment of the epidemic. The CTTI strategy entails mobilizing the whole community, and the supports from both citizens and the public health sectors are indispensable [ 14 , 38 ].…”

Section: Discussionmentioning

confidence: 99%

“…However, our work shows that even with less rigorous measures, for example, a limited round of mass testing, the local transmission can be mitigated quickly. And the promotion of self-screening may also be an optional strategy to save resources for testing [ 38 ]. In addition, a more effective mass testing strategy can be implemented in the city or region with the constraint of the testing capacity, such as combining with the health code system, prioritizing testing the individuals in higher-risk areas and yellow code holders (Additional file 1 : Fig.…”

Section: Discussionmentioning

confidence: 99%

“…We estimate the following parameters, including the probability of transmission per contact and the contact rate in each stage, by using a Monte-Carlo-based Bayesian modeling framework [ 37 , 38 ]. We sample 100,000 parameter vectors from the uniform prior distribution (Additional file 1 : Table S1), and we choose the 1000 best-fitting parameter vectors based on the modified normalized mean square error (NMSE) indicator by comparing data and model predictions of cumulative confirmed cases and cumulative isolated individuals.…”

Section: Methodsmentioning

confidence: 99%

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Assessing the mechanism of citywide test-trace-isolate Zero-COVID policy and exit strategy of COVID-19 pandemic

et al. 2022

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Background Countries that aimed for eliminating the cases of COVID-19 with test-trace-isolate policy are found to have lower infections, deaths, and better economic performance, compared with those that opted for other mitigation strategies. However, the continuous evolution of new strains has raised the question of whether COVID-19 eradication is still possible given the limited public health response capacity and fatigue of the epidemic. We aim to investigate the mechanism of the Zero-COVID policy on outbreak containment, and to explore the possibility of eradication of Omicron transmission using the citywide test-trace-isolate (CTTI) strategy. Methods We develop a compartmental model incorporating the CTTI Zero-COVID policy to understand how it contributes to the SARS-CoV-2 elimination. We employ our model to mimic the Delta outbreak in Fujian Province, China, from September 10 to October 9, 2021, and the Omicron outbreak in Jilin Province, China for the period from March 1 to April 1, 2022. Projections and sensitivity analyses were conducted using dynamical system and Latin Hypercube Sampling/ Partial Rank Correlation Coefficient (PRCC). Results Calibration results of the model estimate the Fujian Delta outbreak can end in 30 (95% confidence interval CI: 28–33) days, after 10 (95% CI: 9–11) rounds of citywide testing. The emerging Jilin Omicron outbreak may achieve zero COVID cases in 50 (95% CI: 41–57) days if supported with sufficient public health resources and population compliance, which shows the effectiveness of the CTTI Zero-COVID policy. Conclusions The CTTI policy shows the capacity for the eradication of the Delta outbreaks and also the Omicron outbreaks. Nonetheless, the implementation of radical CTTI is challenging, which requires routine monitoring for early detection, adequate testing capacity, efficient contact tracing, and high isolation compliance, which constrain its benefits in regions with limited resources. Moreover, these challenges become even more acute in the face of more contagious variants with a high proportion of asymptomatic cases. Hence, in regions where CTTI is not possible, personal protection, public health control measures, and vaccination are indispensable for mitigating and exiting the COVID-19 pandemic. Graphical Abstract

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

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Assessing the mechanism of citywide test-trace-isolate Zero-COVID policy and exit strategy of COVID-19 pandemic

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“…We investigate five different scenarios listed in Table 4, by presenting the projection of daily new infections in LRG and HRG (per 100 000 individuals). In scenarios 1-3, the projection of mean, and 95% confidence interval of daily new infections are obtained from 5000 parameter sets sampling from the prior distribution (uniform) of parameters, by the Latin hypercube sampling (LHS) method 30,31 . We only present the mean of all the simulations in scenarios 2 and 3 for an intuitive interpretation of results.…”

Section: Methodsmentioning

confidence: 99%

Modelling vaccination and control strategies of outbreaks of monkeypox at gatherings

Yuan

Tan

Yang

et al. 2022

Preprint

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Background Monkeypox cases keep soaring in non-endemic's countries and areas in the last few months, leading to the WHO declaring a Public Health Emergency of International Concern. The ongoing and coming festivals, parties and holidays gathering events are causing increased concerns about possible outbreaks. Methods We considered a hypothetical metropolitan city and modelled the transmission of monkeypox virus in humans in high-risk (HRG) and low-risk groups (LRG) using a Susceptible-Exposed-Infectious-Recovered (SEIR) model and incorporated gathering events. Model simulations assessed how the current vaccination strategy combined with other public health measures can contribute to mitigating or halting outbreaks from mass gathering events. Results The risk of a monkeypox outbreak remains high on the occasion of mass gathering events in the absence of public health control measures. However, the outbreaks can be well controlled by cutting off transmission by isolating confirmed cases and inoculating their close contacts. Also, Post Exposure Prophylaxis is more effective for containment in the summer gatherings than a broad vaccination campaign in HRG, taking into account the time needed for developing the immune response and the availability of vaccine. The number of attendees and effective contacts during the gathering are the factors that need more attention by public health authorities to prevent a burgeoning outbreak. Moreover, restricting attendance through vaccination requirements can help secure mass gathering events. Conclusion Gathering events can be made safe with some restrictions of either the number and density of attendees in the gathering, or vaccination requirements. The ring vaccination strategy inoculating close contacts of confirmed cases may not be enough to prevent potential outbreaks, however, mass gatherings can be rendered safe if that strategy is combined with public health measures, including rigorous contact tracing, testing, identifying and isolating cases. Compliance of the community and promotion of awareness are also indispensable to the containment.

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“…In [3], the authors develop a mathematical model to examine the impact of nonpharmaceutical interventions, including the COVID test, genome sequencing test capacity, contact tracing, and quarantine strength, on the induced epidemic wave. A novel compartmental model which captures new strategies that promote self-testing and adjust the eligibility for PCR tests, social behaviours, booster vaccine campaigns, and features of the newest variant Omicron is presented in [4]. However, to our knowledge, none of the above models incorporates the effects of potential SARS-CoV-2 variants together with the treatment and health precautions in the spread of In this paper, we present a compartmental model of a disease transmission with one virus and its variant with treatment and health precautions.…”

Section: Introductionmentioning

confidence: 99%

A Mathematical Model for a Transmissible Disease with a Variant

Otto

Amidou

2022

Journal of Applied Mathematics

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The outbreak of the Coronavirus (COVID-19) pandemic around the world has caused many health and socioeconomic problems, and the identification of variants like Delta and Omicron with similar and often even more transmissible modes of transmission has motivated us to do this study. In this article, we have proposed and analyzed a mathematical model in order to study the effect of health precautions and treatment for a disease transmitted by contact in a constant population. We determined the four equilibria of the system of ordinary differential equations representing the model and characterized their existence using exact methods of algebraic geometry and computer algebra. The model is studied using the stability theory for systems of differential equations and the basic reproduction number R 0 . The stability of the equilibria is analyzed using the Lienard-Chipart criterion and Lyapunov functions. The asymptotic or global stability of endemic equilibria is established, and the disease-free equilibrium is globally asymptotically stable if R 0 < 1 . Model simulation is done with Python software to study the effects of health precautions and treatment, and the results are analyzed. It is observed that if the rate of treatment and compliance with health precautions are high, the number of infections decreases in the classes of infectious and is canceled out over time. It is concluded that the high treatment rate accompanied by a suitable rate of compliance with health precautions allows for the control the disease.

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Projections of the transmission of the Omicron variant for Toronto, Ontario, and Canada using surveillance data following recent changes in testing policies

Cited by 17 publications

References 32 publications

Assessing the mechanism of citywide test-trace-isolate Zero-COVID policy and exit strategy of COVID-19 pandemic

Assessing the mechanism of citywide test-trace-isolate Zero-COVID policy and exit strategy of COVID-19 pandemic

Modelling vaccination and control strategies of outbreaks of monkeypox at gatherings

A Mathematical Model for a Transmissible Disease with a Variant

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