title: The impact of stratified immunity on the transmission dynamics of influenza.
abstract: Although empirical studies show that protection against influenza infection in humans is closely related to antibody titres, influenza epidemics are often described under the assumption that individuals are either susceptible or not. Here we develop a model in which antibody titre classes are enumerated explicitly and mapped onto a variable scale of susceptibility in different age groups. Fitting only with pre- and post-wave serological data during 2009 pandemic in Hong Kong, we demonstrate that with stratified immunity, the timing and the magnitude of the epidemic dynamics can be reconstructed more accurately than is possible with binary seropositivity data. We also show that increased infectiousness of children relative to adults and age-specific mixing are required to reproduce age-specific seroprevalence observed in Hong Kong, while pre-existing immunity in the elderly is not. Overall, our results suggest that stratified immunity in an aged-structured heterogeneous population plays a significant role in determining the shape of influenza epidemics.
authors.affiliation: MRC Centre for Outbreak Analysis and Disease Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom.
authors.forename: Hsiang-Yu
authors.initials: HY
authors.lastname: Yuan
authors.affiliation: Respiratory Diseases Department, Public Health England, London, United Kingdom; Centre for the Mathematical Modelling of Infectious Disease, Department of Infectious Disease Epidemiology, London School of Hygiene & Tropical Medicine, London, United Kingdom. Electronic address: marc.baguelin@phe.gov.uk.
authors.forename: Marc
authors.initials: M
authors.lastname: Baguelin
authors.affiliation: The Jockey Club School of Public Health and Primary Care, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China; Stanley Ho Centre for Emerging Infectious Diseases, The Chinese University of Hong Kong, Hong Kong Special Administrative Region, China; WHO Collaborating Centre for Infectious Disease Epidemiology and Control, School of Public Health, Li Ka Shing Faculty of Medicine, The University of Hong Kong, Hong Kong Special Administrative Region, China.
authors.forename: Kin O
authors.initials: KO
authors.lastname: Kwok
authors.affiliation: MRC Centre for Outbreak Analysis and Disease Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom.
authors.forename: Nimalan
authors.initials: N
authors.lastname: Arinaminpathy
authors.affiliation: MRC Centre for Outbreak Analysis and Disease Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom; Respiratory Diseases Department, Public Health England, London, United Kingdom.
authors.forename: Edwin
authors.initials: E
authors.lastname: van Leeuwen
authors.affiliation: MRC Centre for Outbreak Analysis and Disease Modelling, Department of Infectious Disease Epidemiology, School of Public Health, Imperial College London, London, United Kingdom. Electronic address: s.riley@imperial.ac.uk.
authors.forename: Steven
authors.initials: S
authors.lastname: Riley
mesh_terms: D000293:Adolescent; D000328:Adult; D017677:Age Distribution; D000368:Aged; D004198:Disease Susceptibility / Q000453:epidemiology / Q000276:immunology; D005260:Female; D006723:Hong Kong / Q000453:epidemiology; D006801:Humans; D053118:Influenza A Virus, H1N1 Subtype / Q000276:immunology; D007251:Influenza, Human / Q000453:epidemiology* / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D058873:Pandemics; D016036:Seroepidemiologic Studies; D055815:Young Adult
keywords: Age-specific seroprevalence; Antibody responses; Epidemic model; Inferring transmission dynamics; Influenza; Stratified immunity