COVID-19 Pandemic
Evaluating Age-Based Transmission Dynamics of COVID-19 in Household Settings William Lyon* William Lyon Bridget Kruszka Ryan Murphy
Background: In this study, we aim to better understand the dynamics of household transmission of COVID-19, with a focus on age-specific transmission patterns within household clusters. Improved understanding of general household risk may inform public health recommendations in the future.
Methods: Using data from California’s CalCONNECT contact tracing platform, a retrospective cohort study was conducted from June 2020 to June 2021 of COVID-19 households clusters. Possible transmission events in household clusters were identified when the serial interval of the household index case and a secondary case was 14 days or fewer. The index case was defined as earliest laboratory confirmed SARS-CoV-2 infection in the household. Odds ratios were calculated using a logistic regression model, adjusted for sociodemographic covariates at both individual and household levels. The resulting contrasts were visually displayed in a heatmap, scaled by probability.
Results: A total of 291,768 household contacts from 116,584 households with a COVID-19 index case were analyzed. Compared to the reference group of households with index cases aged 40-60 years, higher risk of transmission was found in households with index cases aged 0-5 (OR=1.08, 95%CI=1.03-1.13), 6-10 (OR=1.11, 95%CI=1.03-1.13), and 11-13 (OR=1.13, 95%CI= 1.07-1.18). Lower risk was noted for ages 14-18 (OR=0.93, 95%CI=0.90-0.95), 19-25 (OR=0.84, 95%CI=0.82-0.87), and 26-39 (OR=0.96, 95%CI=0.94-0.98). No significant risk difference was observed in households with index cases aged 65+ (OR=1.00, 95%CI=0.97-1.04). The interaction between the index and household contact age groups, particularly trends among young children and older adults, is visually detailed in heatmap format(see figure).
Conclusion: Younger COVID-19 index cases were associated with higher risk of transmission among household contacts. These results suggest an importance of age-based strategies in public health mitigation efforts against the spread of COVID-19.
