Understanding COVID-19 dynamics and the effects of interventions in the Philippines: A mathematical modelling study

Caldwell, Jaime M.; Lara-Tuprio, Elvira de; Teng, Timothy Robin; Estuar, Maria Regina Justina E.; Sarmiento, Raymond Francis; Abayawardana, Milinda; Leong, Robert Neil F.; Gray, Richard T.; Wood, James G.; McBryde, Emma S.; Ragonnet, Romain; Trauer, James M

doi:10.1101/2021.01.14.21249848

Cited by 3 publications

(1 citation statement)

References 31 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The application of a similar modelling framework is described elsewhere (Caldwell et al, 2021) and the full model description (including differential equations) is provided in the Supplementary File, with all code publicly available through https://github.com/monashemu/AuTuMN/. The model consists of a modified susceptible (S)-exposed (E)-infectious (I)-recovered (R) compartment framework.…”

Section: Model Descriptionmentioning

confidence: 99%

Sustaining effective COVID-19 control in Malaysia through large-scale vaccination

Jayasundara¹,

Peariasamy

Law

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

Introduction As of 3rd June 2021, Malaysia is experiencing a resurgence of COVID-19 cases. In response, the federal government has implemented various non-pharmaceutical interventions (NPIs) under a series of Movement Control Orders and, more recently, a vaccination campaign to regain epidemic control. In this study, we assessed the potential for the vaccination campaign to control the epidemic in Malaysia and four high-burden regions of interest, under various public health response scenarios. Methods A modified susceptible-exposed-infectious-recovered compartmental model was developed that included two sequential incubation and infectious periods, with stratification by clinical state. The model was further stratified by age and incorporated population mobility to capture NPIs and micro-distancing (behaviour changes not captured through population mobility). Emerging variants of concern (VoC) were included as an additional strain competing with the existing wild-type strain. Several scenarios that included different vaccination strategies (i.e. vaccines that reduce disease severity and/or prevent infection, vaccination coverage) and mobility restrictions were implemented. Results The national model and the regional models all fit well to notification data but underestimated ICU occupancy and deaths in recent weeks, which may be attributable to increased severity of VoC or saturation of case detection. However, the true case detection proportion showed wide credible intervals, highlighting incomplete understanding of the true epidemic size. The scenario projections suggested that under current vaccination rates complete relaxation of all NPIs would trigger a major epidemic. The results emphasise the importance of micro-distancing, maintaining mobility restrictions during vaccination roll-out and accelerating the pace of vaccination for future control. Malaysia is particularly susceptible to a major COVID-19 resurgence resulting from its limited population immunity due to the historical success of the country in maintaining control throughout much of 2020.

show abstract

Section: Model Descriptionmentioning

confidence: 99%

Sustaining effective COVID-19 control in Malaysia through large-scale vaccination

Jayasundara¹,

Peariasamy

Law

et al. 2021

Preprint

Self Cite

View full text Add to dashboard Cite

show abstract

Vaccines and variants: Modelling insights into emerging issues in COVID-19 epidemiology

Caldwell

McIntosh

et al. 2021

Paediatric Respiratory Reviews

Self Cite

View full text Add to dashboard Cite

Mathematical modelling has played a pivotal role in understanding the epidemiology of and guiding public health responses to the ongoing coronavirus disease of 2019 (COVID-19) pandemic. Here, we review the role of epidemiological models in understanding evolving epidemic characteristics, including the effects of vaccination and Variants of Concern (VoC). We highlight ways in which models continue to provide important insights, including 1) calculating the herd immunity threshold and evaluating its limitations; 2) verifying that nascent vaccines can prevent severe disease, infection, and transmission but may be less efficacious against VoC; 3) determining optimal vaccine allocation strategies under efficacy and supply constraints; and 4) determining that VoC are more transmissible and lethal than previously circulating strains, and that immune escape may jeopardize vaccine-induced herd immunity. Finally, we explore how models can help us anticipate and prepare for future stages of COVID-19 epidemiology (and that of other diseases) through forecasts and scenario projections, given current uncertainties and data limitations.

show abstract

Impact of vaccine supplies and delays on optimal control of the COVID-19 pandemic: mapping interventions for the Philippines

et al. 2021

Self Cite

View full text Add to dashboard Cite

Background Around the world, controlling the COVID-19 pandemic requires national coordination of multiple intervention strategies. As vaccinations are globally introduced into the repertoire of available interventions, it is important to consider how changes in the local supply of vaccines, including delays in administration, may be addressed through existing policy levers. This study aims to identify the optimal level of interventions for COVID-19 from 2021 to 2022 in the Philippines, which as a developing country is particularly vulnerable to shifting assumptions around vaccine availability. Furthermore, we explore optimal strategies in scenarios featuring delays in vaccine administration, expansions of vaccine supply, and limited combinations of interventions. Methods Embedding our work within the local policy landscape, we apply optimal control theory to the compartmental model of COVID-19 used by the Philippine government’s pandemic surveillance platform and introduce four controls: (a) precautionary measures like community quarantines, (b) detection of asymptomatic cases, (c) detection of symptomatic cases, and (d) vaccinations. The model is fitted to local data using an L-BFGS minimization procedure. Optimality conditions are identified using Pontryagin’s minimum principle and numerically solved using the forward–backward sweep method. Results Simulation results indicate that early and effective implementation of both precautionary measures and symptomatic case detection is vital for averting the most infections at an efficient cost, resulting in $$>99\%$$ > 99 % reduction of infections compared to the no-control scenario. Expanding vaccine administration capacity to 440,000 full immunizations daily will reduce the overall cost of optimal strategy by $$25\%$$ 25 % , while allowing for a faster relaxation of more resource-intensive interventions. Furthermore, delays in vaccine administration require compensatory increases in the remaining policy levers to maintain a minimal number of infections. For example, delaying the vaccines by 180 days (6 months) will result in an $$18\%$$ 18 % increase in the cost of the optimal strategy. Conclusion We conclude with practical insights regarding policy priorities particularly attuned to the Philippine context, but also applicable more broadly in similar resource-constrained settings. We emphasize three key takeaways of (a) sustaining efficient case detection, isolation, and treatment strategies; (b) expanding not only vaccine supply but also the capacity to administer them, and; (c) timeliness and consistency in adopting policy measures. Graphic Abstract

show abstract

Understanding COVID-19 dynamics and the effects of interventions in the Philippines: A mathematical modelling study

Cited by 3 publications

References 31 publications

Sustaining effective COVID-19 control in Malaysia through large-scale vaccination

Sustaining effective COVID-19 control in Malaysia through large-scale vaccination

Vaccines and variants: Modelling insights into emerging issues in COVID-19 epidemiology

Impact of vaccine supplies and delays on optimal control of the COVID-19 pandemic: mapping interventions for the Philippines

Contact Info

Product

Resources

About