Alliance for Pandemic Preparedness

April 15, 2020

Household secondary attack rate of COVID-19 and associated determinants



  • Jing et al. used a comprehensive contact-tracing dataset to estimate population-level effective RO and individual-level SAR in the household setting and to assess age effects on transmissibility and infectivity of COVID-19 cases during the incubation period. They reported household SAR to be 13.8% between relatives within households and 19.3% in same residential address as the cases. Children (<20yrs) were 74% less likely to be infected compared to the elderly (≥ 60 yrs. old).
  • A single COVID-19 case infected 0.48 close contacts within a household, increasing to 0.62 without isolation. They concluded that SARS-CoV-2 is more transmissible within households than SARS-CoV and MERS-CoV, and that the elderly are the most vulnerable. Case finding and isolation alone may be inadequate to contain the pandemic unless combined with restriction of human movement.

Jing et al. (April 15, 2020). Household secondary attack rate of COVID-19 and associated determinants. Pre-print downloaded Apr 15 from