1. Risk factors for COVID-19 transmission in England: a multilevel modelling study using routine contact tracing data.
- Author
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Moore HL, Turner C, Rawlinson C, Chen C, Verlander NQ, Anderson C, and Hughes GJ
- Subjects
- Humans, England epidemiology, Aged, Middle Aged, Risk Factors, Female, Male, Adult, Adolescent, Young Adult, Child, Preschool, SARS-CoV-2, Child, Aged, 80 and over, Infant, Infant, Newborn, COVID-19 transmission, COVID-19 epidemiology, Contact Tracing
- Abstract
Contact tracing for COVID-19 in England operated from May 2020 to February 2022. The clinical, demographic and exposure information collected on cases and their contacts offered a unique opportunity to study secondary transmission. We aimed to quantify the relative impact of host factors and exposure settings on secondary COVID-19 transmission risk using 550,000 sampled transmission links between cases and their contacts. Links, or 'contact episodes', were established where a contact subsequently became a case, using an algorithm accounting for incubation period, setting, and contact date. A mixed-effects logistic regression model was used to estimate adjusted odds of transmission. Of sampled episodes, 8.7% resulted in secondary cases. Living with a case (71% episodes) was the most significant risk factor (aOR = 2.6, CI = 1.9-3.6). Other risk factors included unvaccinated status (aOR = 1.2, CI = 1.2-1.3), symptoms, and older age (66-79 years; aOR = 1.4, CI = 1.4-1.5). Whilst global COVID-19 strategies emphasized protection outside the home, including education, travel, and gathering restrictions, this study evidences the relative importance of household transmission. There is a need to reconsider the contribution of household transmission to future control strategies and the requirement for effective infection control within households.
- Published
- 2024
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