The Household Secondary Attack Rate of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): A Rapid Review
Published in Clinical Infectious Diseases, 2021
Recommended citation: Hannah F Fung, Leonardo Martinez, Fernando Alarid-Escudero, Joshua A Salomon, David M Studdert, Jason R Andrews, Jeremy D Goldhaber-Fiebert, Stanford-CIDE Coronavirus Simulation Model (SC-COSMO) Modeling Group, The Household Secondary Attack Rate of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2): A Rapid Review, Clinical Infectious Diseases, Volume 73, Issue Supplement_2, 1 August 2021, Pages S138–S145, https://doi.org/10.1093/cid/ciaa1558. https://doi.org/10.1093/cid/ciaa1558
Abstract
Background
Although much of the public health effort to combat coronavirus disease 2019 (COVID-19) has focused on disease control strategies in public settings, transmission of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) within households remains an important problem. The nature and determinants of household transmission are poorly understood.
Methods
To address this gap, we gathered and analyzed data from 22 published and prepublished studies from 10 countries (20 291 household contacts) that were available through 2 September 2020. Our goal was to combine estimates of the SARS-CoV-2 household secondary attack rate (SAR) and to explore variation in estimates of the household SAR.
Results
The overall pooled random-effects estimate of the household SAR was 17.1% (95% confidence interval [CI], 13.7–21.2%). In study-level, random-effects meta-regressions stratified by testing frequency (1 test, 2 tests, >2 tests), SAR estimates were 9.2% (95% CI, 6.7–12.3%), 17.5% (95% CI, 13.9–21.8%), and 21.3% (95% CI, 13.8–31.3%), respectively. Household SARs tended to be higher among older adult contacts and among contacts of symptomatic cases.
Conclusions
These findings suggest that SARs reported using a single follow-up test may be underestimated, and that testing household contacts of COVID-19 cases on multiple occasions may increase the yield for identifying secondary cases.