The COVID-19 Pandemic: The epidemic curve soars across the U.S. and flattens in Colorado
Dec 14, 2020
The devastating course of the COVID-19 pandemic in the United States became even more dire this week. There had been warnings of a “dark winter” from many; predictably it has arrived. The daily death count in the United States, now reaching over 3,000, has been compared with the numbers from the September 11 terrorist attacks (2,605) and Pearl Harbor (2,403). The Institute for Health Metrics and Evaluation (IHME) places COVID-19 as the leading cause of death in the United States and Colorado at the moment, placing well above ischemic heart disease. IHME projects that COVID-19 deaths in the United States could total 500,000 by April 1. The approval of the first SARS-CoV-2 vaccine by the Food and Drug Administration on December 11 is good news and immunization of the highest priority groups begins nationwide today. But by April 1, vaccination will make only a small dent in the deaths caused by COVID-19.
The course of the pandemic varies widely across the states. In Colorado, transmission control declined from mid-September through mid-November, but has fortunately improved over the last three weeks. We track hospitalizations for COVID-19, which peaked at 1,841 on December 2 and dropped to 1,513 on December 13. For comparison, the April peak was at 901 at a time when length of stay in the hospital was substantially longer than now. Thanksgiving travel began around November 20 and we are 20 days past Thanksgiving Day. Our analyses of data on mobile phone movement show that people visited and mingled on Thanksgiving Day, but not nearly so much as in 2019. The continued drop in hospitalizations and the modeling results suggest that Colorado has escaped a Thanksgiving-caused rise in the epidemic curve and will be relatively well positioned for handling a possible drop in transmission control with the holidays.
Of course, the next question is why—why has transmission control improved in Colorado in recent weeks? Policy measures may be making the difference with 15 counties moving to Level Red on the COVID-19 dial dashboard on November 20 followed by an additional seven on November 22. The move from Level Orange triggered a number of measures, including closure of indoor dining. Transmission control also captures the integrated consequences of the behavior of all Coloradans; the gain in transmission control likely also reflects greater adherence to behaviors that reduce transmission of the virus. But, with the start of the December holidays only a week away, we need to stick with the policy measures and behaviors that have protected us. Even with the epidemic curve turning down, the prevalence of infection is high (one of 42 Coloradans last week) and a turn-up in the epidemic curve would quickly reverse the gains made in December.
The New York Times continues to explore critical patterns of the epidemic, including the numbers of infections related to collegiate athletics and the spillover of infections from campuses to communities. And, there is this newspaper article title for one of Saturday's football games: “Down 33 players, Gophers respond with 24-17 win over Nebraska.” Why are contact sports being played and at what costs for players and communities? A remarkable report in Science, released on December 10, provides elegant documentation of a superspreading event in Boston associated with an international business conference. The investigation incorporates careful molecular epidemiology, supporting a projection that the event led to 50,000 cases in the United States and several 100,000 more globally.
Winter starts in a week and ends on March 20, 2021. By then, we will rejoice the end of our “dark winter” and the arrival of spring with anticipation of moving towards herd immunity in the months to come as more and more people are vaccinated.
And as a reminder, listen to Nicholas Christakis, author of Apollo’s Arrow, on Wednesday morning at 8:30 a.m. in the school’s collaborative series with the Denver Museum of Nature and Science. And another reminder: the State of the School presentation on Thursday at noon.
Be patient and hang in for a few more months,
