Abstract On November 24, 2021, South African scientists announced the rapid spread of a
new SARS-CoV-2 variant. Within days, the WHO named the variant Omicron and classified it
as a variant of concern (VOC). As of December 15, 2021, many of Omicron's epidemiological
characteristics remain uncertain, including its intrinsic transmissibility, ability to evade
vaccine-acquired and infection-acquired immunity, and severity. To support situational
awareness and planning in the United States, we simulated the emergence and spread of …

Abstract As of January 6, 2021, the highly-transmissible SARS-CoV-2 Omicron variant is
driving the largest COVID-19 wave in the US to date. The numbers of new cases and
hospitalizations continue to rise, straining healthcare systems around the country. On
December 16, 2021, we posted projections for the emergence of the Omicron variant under
18 plausible scenarios [1]. At that time, many of Omicron's epidemiological characteristics
were uncertain. Recent studies suggest that the Omicron variant is more transmissible, more …