Abstract
Introduction
COVID-19 has spread rapidly in the United States since January 2020.
Methods
We estimated mean epidemic doubling time, an important measure of epidemic growth, nationally, by state, and in association with stay-at-home orders.
Results
Epidemic doubling time in the US was 2.68 days (95%CI:2.30–3.24) prior to widespread mitigation efforts, increasing by 460% to 15 days (95%CI:12.89-17.94) during the mitigation phase. Among states without stay-at-home orders, median increase in doubling time was 60% (95%CI: 9.2-223.3) while for states with stay-at-home orders, median increase was 269% (95%CI: 277.0-394.0).
Discussion
Statewide mitigation strategies were strongly associated with increased epidemic doubling time.
Keywords: COVID-19, Coronavirus, SARS-CoV-2, epidemic doubling time