During the early stages of the pandemic, the big story in the United States was testing: The federal government’s initial failure to produce a working test and scale up its production meant that the country struggled for months to keep up with the virus’s spread. In May, the Harvard Global Health Institute estimated that the U.S. needed to perform 1 million tests a day to contain the outbreak by identifying cases before they spread, a mark we didn’t surpass until late September. After that, testing finally picked up speed: By late November, the seven-day daily-testing average had jumped to more than 1.8 million.
But lately, daily tests have plateaued. After nearly breaking the 2 million mark in mid-January, daily tests today remain stuck at about 1.8 million. The stall-out is a mix of good and bad news: Although more testing would give us a clearer view of the outbreak, lower testing numbers reflect a pandemic in retreat, as demand for testing tends to rise with the spread of the virus.
Much of the data we have about the pandemic are messy, but that is especially true with testing. The numbers of tests that are used, and the results of those tests, are disrupted by weekends and holidays, and the results of many rapid tests aren’t reported at all. Even though the testing information is jittery, we can still see how it fluctuates with the coronavirus’s spread by comparing it with the number of COVID-19 hospitalizations, which is the most reliable pandemic metric we have. U.S. hospitalizations peaked three times, corresponding with the pandemic’s three surges. Nationwide testing trends paint a somewhat different picture—hospitalizations peaked in April but testing didn’t, because the U.S. was struggling with its testing—but there is still a clear pattern. Here’s what the two metrics look like plotted together.
Around Thanksgiving, there was a major dip in testing, which was likely a combination of a bump in demand before the holiday, a drop-off in demand right after, and a lag in states’ reporting their data. A similar pattern occurred around Christmas. But taken as a whole, the numbers suggest that when pandemic conditions have worsened, the demand for testing has increased.