Alliance for Pandemic Preparedness

May 13, 2020

The Real Time Effective Reproductive Number for COVID-19 in the United States

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  • Keegan et al. compared the reproductive number (Rt) calculated between two methods, the Wallinga and Teunis (WT) method (forward-looking) and the Cori method (backward-looking) to estimate the impact of all combined non-pharmaceutical interventions in US. 
  • Results show that most states have been able to reduce the Rt of SARS-CoV-2. However, few states have demonstrated an ability to maintain Rt below a value of 1. The median difference in timing of Rt<1 between the two methods is 6.5 days, highlighting the importance of method selection for Rt estimation to inform policy decision making. 

Keegan et al. (May 13, 2020). The Real Time Effective Reproductive Number for COVID-19 in the United States. Pre-print downloaded May 13 from https://doi.org/10.1101/2020.05.08.20095703