The impact of household structure on disease-induced herd immunity

Abstract The disease-induced herd immunity level %$h_D%$ is the fraction of the population that must be infected by an epidemic to ensure that a new epidemic among the remaining susceptible population is not supercritical. For a homogeneously mixing population %$h_D%$ equals the classical herd immunity level %$h_C%$, which is the fraction of the population that must be vaccinated in advance of an epidemic so that the epidemic is not supercritical. For most forms of heterogeneous mixing %$h_D<h_C%$, sometimes dramatically so. For an SEIR (susceptible %$\rightarrow %$ exposed %$\rightarrow %$ infective %$\rightarrow %$ recovered) model of an epidemic among a population that is partitioned into households, in which individuals mix uniformly within households and, in addition, uniformly at a much lower rate in the population at large, we show that %$h_D>h_C%$ unless variability in the household size distribution is sufficiently large. Thus, introducing household structure into a model typically has the opposite effect on disease-induced herd immunity than most other forms of population heterogeneity. We reach this conclusion by considering an approximation %${\tilde{h}}_D%$ of %$h_D%$, supported by numerical studies using real-world household size distributions. For %$n=2, 3%$, we prove that %${\tilde{h}}_D>h_C%$ when all households have size n, and conjecture that this inequality holds for any common household size n. We prove results comparing %${\tilde{h}}_D%$ and %$h_C%$ for epidemics which are highly infectious within households, and also for epidemics which are weakly infectious within households..

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:87

Enthalten in:

Journal of mathematical biology - 87(2023), 6 vom: 08. Nov.

Sprache:

Englisch

Beteiligte Personen:

Ball, Frank [VerfasserIn]
Critcher, Liam [VerfasserIn]
Neal, Peter [VerfasserIn]
Sirl, David [VerfasserIn]

Links:

Volltext [kostenfrei]

Themen:

Disease-induced herd immunity level
Household epidemic model
SEIR epidemic
Vaccine-induced herd immunity level

Anmerkungen:

© The Author(s) 2023

doi:

10.1007/s00285-023-02010-7

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

SPR053661419