"Based on what we’ve seen over the last eight months of state-reported COVID-19 data, we think two big, potentially misleading things are about to happen to the testing, case, and death numbers that allow us to track the pandemic in the United States.
First, by Thanksgiving Day and perhaps as early as Wednesday, all three metrics will flatten out or drop, probably for several days. This decrease will make it look like things are getting better at the national level. Then, in the week following the holiday, our test, case, and death numbers will spike, which will look like a confirmation that Thanksgiving is causing outbreaks to worsen. But neither of these expected movements in the data will necessarily mean anything about the state of the pandemic itself. Holidays, like weekends, cause testing and reporting to go down and then, a few days later, to "catch up." So the data we see early next week will reflect not only actual increases in cases, test, and deaths, but also the potentially very large backlog from the holiday. "