July 30, 2020

Secondary Attack Rate of COVID-19 in Household Contacts: Systematic Review

Category: Article Summary

Topic: Transmission

• A systematic review (13 articles) showed that the household secondary attack rate of COVID-19 varies widely across countries with a range of 5%–50%, unaffected by confounders such as population of the country, lockdown status and geographic location. The symptomatic status of the index case was strongly associated with the secondary attach rate, with very low transmission probability during the asymptomatic phase. The review suggested greater vulnerability of spouses and the elderly population to secondary transmission compared to other household members. Quarantining and isolation were the most effective strategies for prevention. 

Shah et al. (July 2020). Secondary Attack Rate of COVID-19 in Household Contacts: Systematic Review. QJM. https://doi.org/10.1093/qjmed/hcaa232