February 25, 2021

Household Secondary Attack Rate of COVID-19 by Household Size and Index Case Characteristics

Category: Article Summary

Topic: Transmission

Keywords (Tags): transmission

[Pre-print, not peer-reviewed] A population-wide study in Ontario, Canada including nearly 85,000 household contacts from nearly 30,000 households between July to November 2020 found that, while the overall household secondary attack rate (SAR) for SARS-CoV-2 transmission was 20%, 12% of households had a SAR ≥75%. Households in which the index case was symptomatic and had longer delays between symptom onset and test seeking were more likely to have a higher SAR; each day of delay in testing after symptom onset was associated with a 1.8% increase in SAR. The SAR was similar by household size, but the SAR was greater in larger households in the most ethnically diverse neighborhoods compared to those in the least ethnically diverse neighborhoods (20% vs 15%).

Tibebu et al. (Feb 25, 2021). Household Secondary Attack Rate of COVID-19 by Household Size and Index Case Characteristics. Pre-print downloaded Feb 25 from https://doi.org/10.1101/2021.02.23.21252287