Host heterogeneity and respiratory disease dynamics: From structural inequity to immune history

Host heterogeneity is a core driver of infectious disease dynamics and has been widely explored in ecology and evolution. However, in human populations, social inequity remains underexplored as a source of heterogeneity despite having long been identified as a threat to global health and infectious disease control. In this work, we draw from established ecological frameworks such as metapopulation theory and classic resource consumption curves to explore the impact of sociodemographic disparities and host immune history on human coronavirus dynamics. First, we characterize national and subnational socioeconomic (SES) disparities in COVID-19 vaccination over time, and used transmission models to show that improving the speed and timing of vaccination for all groups has a greater impact on disease-related deaths than trying to resolve deeply entrenched disparities. Second, we explore the importance of incorporating known socioeconomic disparities into transmission models, comparing models with and without this stratification. We find that a model adapted to include SES-stratified parameters returns higher estimates of disease burden than its SES-agnostic counterpart. Third, we use transmission models to quantify the effect of SARS-CoV-2 bivalent booster formulations in populations with high pre-existing immunity, showing that booster implementation is more important than booster formulation. Fourth, we reimagine serocatalytic models for seasonal coronaviruses, finding that models capturing a gradient of serostatus always outperform binary classifications of seropositive and seronegative. These new models and theoretical frameworks can be leveraged in the future to gain insight into SARS-CoV-2 and other infectious diseases. Finally, we analyze the impact of spatial connectivity of populations on respiratory disease dynamics in Illinois, finding that increasing community connectivity across vulnerable groups and promoting effective isolation of individuals during infection can reduce disparities and disease burden for all. Across the studies presented here, we found that the impact of host heterogeneity on disease dynamics was often counterintuitive, highlighting that developing a thorough understanding of social disparities and their consequences is crucial for disease control.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Ecol, Evol, Conservation Biol

Grantor

University of Illinois Urbana-Champaign

Year dc:date

2025

Author dc:creator

• Larsen, Soren L.

Contributors dc:contributor

• Martinez, Pamela P
• Cáceres, Carla E
• Smith, Rebecca L
• Kirkpatrick, Kay
• Kraay, Alicia NM

• SARS-CoV-2
• influenza
• seasonal coronavirus
• social disparities
• infectious disease dynamics
• mathematical modeling
• SEIR
• host heterogeneity

Statement dc:rights

• Copyright 2025 Soren Larsen

Language dc:language

eng, en

Handle dc:identifier

https://hdl.handle.net/2142/129501

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/129501