Doctoral Degrees ((SACEMA) South African Centre for Epidemiological Modelling and Analysis)

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Browsing Doctoral Degrees ((SACEMA) South African Centre for Epidemiological Modelling and Analysis) by browse.metadata.advisor "Ferrari, Matthew J."

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    Modelling outbreak response intervention strategies for decision-making
    (Stellenbosch : Stellenbosch University, 2022-04) Azam, James Mba; Pulliam, Juliet R. C.; Pulliam, Juliet Rachel Crowder, 1979-; Ferrari, Matthew J.; Faulty of Medicine and Health Sciences. SACEMA: South African Centre for Epidemiological Modelling and Analysis.
    ENGLISH SUMMARY: Outbreaks of infectious diseases like measles and COVID-19 continue to threaten public health. Consequently, outbreak response decision-making is in constant need of advancements. Mathematical models of infectious diseases, which provide evidence based insights about pathogen spread and the impact of interventions, form an essential component of outbreak response decision-making. In this dissertation, I make three contributions in that regard. First, I conduct a systematic review of modelling studies, published during 1970-2019, that assessed the impact of reactive interventions on real and hypothetical outbreaks of human vaccine-preventable diseases and foot-and-mouth disease (FMD). I extract data including the author affiliation type (academic institution, governmental, and non-governmental organizations), whether there was an author based in the country studied, impact of vaccination, model characteristics, and modelling practices. I use the author affiliation types to group papers into two collaboration types namely, purely academic (papers with only academic author affiliations) and mixed (all other combinations). I analyse time and geographic patterns and differences in model characteristics and practices overall and between the collaboration types. I find that, in the human disease literature, mixed collaborations increased in the past decade, more often included authors based in the country studied and used more complex modelling practices. These patterns could indicate an increased recognition of modelling by decision makers or increased interaction between modellers and decision-makers. Additionally, I observe some contrasting patterns between the human and FMD literature. Second, I investigate the relative logistical and epidemiological benefits of outside cold chain (OCC) delivery of measles vaccines during an outbreak in a hypothetical setting assuming vaccine cold chain challenges. I extend a transmission dynamic model to incorporate key logistical requirements of several cold chain and OCC strategies. I find that OCC delivery of measles vaccines during outbreaks could lead to shorter campaigns, high vaccination coverage, and higher cases averted. Finally, I show how the emergence of a variant strain affects the minimally sufficient response strategy needed to mitigate the outbreak of a hypothetical pathogen. I develop compartmental models that allow the introduction of more transmissible variants with the ability to escape vaccine-induced immunity. I investigate the impact on outbreak size and peak prevalence targets of implementing either vaccination alone or a combination of vaccination and non-pharmaceutical interventions (NPIs). I show that the use of vaccination alone would require a high vaccination coverage and rapid rollout speed but adding on NPIs could reduce the vaccination coverage and rollout speed required to achieve the targets while also accounting for the risk of variant emergence. In conclusion, this dissertation makes advances that could potentially: (1) initiate discussions on the impact of modelling in outbreak response and the need for increased collaboration between model developers and users, (2) lead to advocacy towards innovations in measles outbreak response vaccination, and (3) contribute to the theory of outbreak response planning, especially in the way uncertainty regarding the potential emergence of a variant is considered in outbreak response decision-making.