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IntroductionRespiratory syncytial virus (RSV) causes a significant respiratory disease burden in the under 5 population. The transmission pathway to young children is not fully quantified in low-income settings, and this information is required to design interventions.MethodsWe used an individual level transmission model to infer transmission parameters using data collected from 493 individuals distributed across 47 households over a period of 6 months spanning the 2009/2010 RSV season. A total of 208 episodes of RSV were observed from 179 individuals. We model competing transmission risk from within household exposure and community exposure while making a distinction between RSV groups A and B.ResultsWe find that 32-53% of all RSV transmissions are between members of the same household; the rate of pair-wise transmission is 58% (95% CrI: 30-74%) lower in larger households (≥8 occupants) than smaller households; symptomatic individuals are 2-7 times more infectious than asymptomatic individuals i.e. 2.48 (95% CrI: 1.22-5.57) among symptomatic individuals with low viral load and 6.7(95% CrI: 2.56-16) among symptomatic individuals with high viral load; previous infection reduces susceptibility to re-infection within the same epidemic by 47% (95% CrI: 17%-68%) for homologous RSV group and 39% (95%CrI: -8%-69%) for heterologous group; RSV B is more frequently introduced into the household, and RSV A is more rapidly transmitted once in the household.DiscussionOur analysis presents the first transmission modelling of cohort data for RSV and we find that it is important to consider the household social structuring and household size when modelling transmission. The increased infectiousness of symptomatic individuals implies that a vaccine against RSV related disease would also have an impact on infection transmission. Together, the weak cross immunity between RSV groups and the possibility of different transmission niches could form part of the explanation for the group co-existence.

Original publication

DOI

10.1016/j.epidem.2018.12.001

Type

Journal article

Journal

Epidemics

Publication Date

06/2019

Volume

27

Pages

1 - 11

Addresses

KEMRI-Wellcome Trust Research Programme, KEMRI Center for Geographical Medical Research-Coast, P.O. Box 230-80108, Kilifi, Kenya; Centre for Mathematical Modelling of Infectious Disease and Department of Global Health and Development, London School of Hygiene and Tropical Medicine, London, WC1H 9SH, UK. Electronic address: ikombe@kemri-wellcome.org.

Keywords

Humans, Respiratory Syncytial Virus, Human, Respiratory Syncytial Virus Infections, Viral Load, Cohort Studies, Family Characteristics, Seasons, Models, Theoretical, Poverty, Adolescent, Child, Child, Preschool, Infant, Rural Population, Kenya, Female, Male, Epidemics