Figure 1.

Epidemiologic curve showing five COVID-19 disease waves in Houston Methodist patients. Number of new COVID-19 cases (y axis) totals are shown as a ±3-day moving average. Each of the five waves is shown in a different color. The first and second waves were composed of a heterogeneous array of SARS-CoV-2 genotypes. The Alpha variant of concern (VOC) shown in the third wave, the Delta VOC shown in the fourth wave, and the Omicron VOC shown in the fifth wave indicate their numeric prominence in those waves. The figure should not be interpreted to mean that all cases in the third, fourth, and fifth waves were caused by Alpha, Delta, and Omicron VOCs, respectively. Rather, they are the dominant single VOCs causing disease in Houston Methodist system patients in those waves. The fifth wave shown includes data through January 5, 2022. The figure was generated with Tableau version 2021.2.7 (Tableau Software, LLC, Seattle, WA), and is adapted with permission from the version presented in Christensen et al.⁶ The curve is essentially superimposable on COVID-19 activity in all metropolitan Houston, Texas.