Modeling the impact of racial and ethnic disparities on COVID-19 epidemic dynamics.

Marc Lipsitch,Kevin C Ma,Stephen Kissler,Yonatan H Grad,Tigist F Menkir

doi:10.7554/elife.66601

Abstract

The impact of variable infection risk by race and ethnicity on the dynamics of SARS-CoV-2 spread is largely unknown. Here, we fit structured compartmental models to seroprevalence data from New York State and analyze how herd immunity thresholds (HITs), final sizes, and epidemic risk change across groups. A simple model where interactions occur proportionally to contact rates reduced the HIT, but more realistic models of preferential mixing within groups increased the threshold toward the value observed in homogeneous populations. Across all models, the burden of infection fell disproportionately on minority populations: in a model fit to Long Island serosurvey and census data, 81% of Hispanics or Latinos were infected when the HIT was reached compared to 34% of non-Hispanic whites. Our findings, which are meant to be illustrative and not best estimates, demonstrate how racial and ethnic disparities can impact epidemic trajectories and result in unequal distributions of SARS-CoV-2 infection. K.C.M. was supported by National Science Foundation GRFP grant DGE1745303. Y.H.G. and M.L. were funded by the Morris-Singer Foundation. M.L. was supported by SeroNet cooperative agreement U01 CA261277.

Highlights

The dynamics of SARS-CoV-2 spread are influenced by population heterogeneity
A simple model where interactions occur proportionally to contact rates reduced the herd immunity thresholds (HITs), but more realistic models of preferential mixing within groups increased the threshold toward the value observed in homogeneous populations
We model the dynamics of COVID-19 infection allowing for social exposure to infection to vary across racial and ethnic groups

Summary

Introduction

The dynamics of SARS-CoV-2 spread are influenced by population heterogeneity. This is especially true for herd immunity, which occurs when susceptible individuals in a population are indirectly protected from infection due to immunity in others. The herd immunity threshold (HIT) is the fraction of the population that is non-susceptible when an unmitigated epidemic reaches its peak, and estimating the HIT for SARS-CoV-2 is important for forecasting the harm associated with letting the epidemic spread in the absence of interventions [1]. Herd immunity for the population overall is achieved earlier because once these individuals are no longer susceptible to infection, further epidemic spread is slowed. The impact of variable infection risk by race and ethnicity on the dynamics of SARS-

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