Household presentation of influenza and acute respiratory illnesses to a primary care sentinel network: retrospective database studies (2013-2018).

BackgroundDirect observation of the household spread of influenza and respiratory infections is limited; much of our understanding comes from mathematical models. The study aims to determine household incidence of influenza-like illness (ILI), lower (LRTI) and upper (URTI) respiratory infections within a primary care routine data and identify factors associated with the diseases' incidence.MethodsWe conducted two five-year retrospective analyses of influenza-like illness (ILI), lower (LRTI) and upper (URTI) respiratory infections using the England Royal College of General Practitioners (RCGP) Research and Surveillance Centre (RSC) primary care sentinel network database; a cross-sectional study reporting incident rate ratio (IRR) from a negative binomial model and a retrospective cohort study, using a shared gamma frailty survival model, reporting hazard ratios (HR). We reported the following household characteristics: children ResultsThe IRR where there was a child ConclusionsPatterns of household incidence can be measured from routine data and may provide insights for the modelling of disease transmission and public health policy