Household Transmission of SARS-CoV-2 from Children and Adolescents

Abstract

To the Editor: Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection in children is often asymptomatic or results in only mild disease. 1 Data on the extent of transmission of SARS-CoV-2 from children and adolescents in the household setting, including transmission to older persons who are at increased risk for severe disease, are limited. 2 After an outbreak of coronavirus disease 2019 (Covid-19) at an overnight camp, 3 we conducted a retrospective cohort study involving camp attendees and their household contacts to assess secondary transmission and factors associated with household transmission (additional details are provided in the Methods section in the Supplementary Appendix, available with the full text of this letter at NEJM.org). We interviewed 224 index patients who were Table 1. Unadjusted and Adjusted Odds Ratio for a Secondary Case of SARS-CoV-2 Infection among Household Contacts.* Variable Univariable Model Multivariable Model Unadjusted Odds Ratio (95% CI) Adjusted Odds Ratio (95% CI) Index patients † Age-yr 7-10 2.3 (0.7-7.0) 0.7 (0.2-2.9) 11-15 1.1 (0.5-2.8) 0.7 (0.3-1.6) 16-19 1.0 (reference) 1.0 (reference) Covid-19 symptom status Symptomatic 5.5 (0.8-40.7) 5.5 (0.8-38.1) Asymptomatic 1.0 (reference) 1.0 (reference) Maintained physical distancing Yes 0.3 (0.1-0.6) 0.4 (0.1-0.9) No 1.0 (reference) 1.0 (reference) Always wore a mask around household contacts Yes 0.2 (0.1-0.6) 0.5 (0.2-1.3) No 1.0 (reference) 1.0 (reference) Household contacts † Contact with index patient ‡ Direct contact 8.2 (2.7-24.7) 5.8 (1.8-18.8) Close contact 5.4 (1.4-20.9) 5.2 (1.2-22.5) Minimal to no contact 1.0 (reference) 1.0 (reference) * A generalized-estimating-equation approach with an exchangeable correlation structure was used to account for intra-household correlation. For the multivariable analysis, key characteristics of the index patients (i.e., age, the presence of coronavirus disease 2019 [Covid-19] symptoms, isolation from other persons, and mask use) and the level of contact between the household member and the index patient were selected. The model was fitted after calculation of variance inflation factors to evaluate the resulting design matrix for multicollinearity; all the variance inflation factor values were below 2, which indicated minimal correlation among the model variables. Confidence intervals were not adjusted for multiplicity. Households with more than one index patient were excluded from the univariable and multivariable models. CI denotes confidence interval, and SARS-CoV-2 severe acute respiratory syndrome coronavirus 2.