Sharing a household with children and risk of COVID-19: a study of over 300,000 adults living in healthcare worker households in Scotland (preprint)

ABSTRACT

ObjectiveChildren are relatively protected from COVID-19, possibly due to cross-protective immunity. We investigated if contact with children also affords adults a degree of protection from COVID-19. DesignCohort study based on linked administrative data. SettingScotland Study populationAll NHS Scotland healthcare workers and their household contacts as of March 2020. Main exposureNumber of young children (0-11 years) living in the participants household. Main outcomesCOVID-19 requiring hospitalisation, and any COVID-19 (any positive test for SARS-CoV-2) in adults aged [≥]18 years between 1 March and 12 October 2020. Results241,266, 41,198, 23,783 and 3,850 adults shared a household with 0, 1, 2, and 3 or more young children respectively. Over the study period, the risk of COVID-19 requiring hospitalisation was reduced progressively with increasing numbers of household children - fully adjusted hazard ratio (aHR) 0.93 per child (95% CI 0.79-1.10). The risk of any COVID-19 was similarly reduced, with the association being statistically significant (aHR per child 0.93; 95% CI 0.88-0.98). After schools reopened to all children in August 2020, no association was seen between exposure to young children and risk of any COVID-19 (aHR per child 1.03; 95% CI 0.92-1.14). ConclusionBetween March and October 2020, living with young children was associated with an attenuated risk of any COVID-19 and COVID-19 requiring hospitalisation among adults living in healthcare worker households. There was no evidence that living with young children increased adults risk of COVID-19, including during the period after schools re-opened.