Our Most Reliable Pandemic Number Is Losing Meaning
A new study suggests that almost half of those hospitalized with COVID-19 have mild or asymptomatic cases.
At least 12,000 Americans have already died from COVID-19 this month, as the country inches through its latest surge in cases. But another worrying statistic is often cited to depict the dangers of this moment: The number of patients hospitalized with COVID-19 in the United States right now is as high as it has been since the beginning of February. It’s even worse in certain places: Some states, including Arkansas and Oregon, recently saw their COVID hospitalizations rise to higher levels than at any prior stage of the pandemic. But how much do those latter figures really tell us? From the start, COVID hospitalizations have served as a vital metric for tracking the risks posed by the disease. Last winter, this magazine described it as “the most reliable pandemic number,” while Vox quoted the cardiologist Eric Topol as saying that it’s “the best indicator of where we are.” On the one hand, death counts offer finality, but they’re a lagging signal and don’t account for people who suffered from significant illness but survived. Case counts, on the other hand, depend on which and how many people happen to get tested. Presumably, hospitalization numbers provide a more stable and reliable gauge of the pandemic’s true toll, in terms of severe disease. But a new, nationwide study of hospitalization records, released as a preprint today (and not yet formally peer reviewed), suggests that the meaning of this gauge can easily be misinterpreted—and that it has been shifting over time. If you want to make sense of the number of COVID hospitalizations at any given time, you need to know how sick each patient actually is. Until now, that’s been almost impossible to suss out. The federal government requires hospitals to report every patient who tests positive for COVID, yet the overall tallies of COVID hospitalizations, made available on various state and federal dashboards and widely reported on by the media, do not differentiate based on severity of illness. Some patients need extensive medical intervention, such as getting intubated. Others require supplemental oxygen or administration of the steroid dexamethasone. But there are many COVID patients in the hospital with fairly mild symptoms, too, who have been admitted for further observation on account of their comorbidities, or because they reported feeling short of breath. Another portion of the patients in this tally are in the hospital for something unrelated to COVID, and discovered that they were infected only because they were tested upon admission. How many patients fall into each category has been a topic of much speculation. In August, researchers from Harvard Medical School, Tufts Medical Center, and the Veterans Affairs Healthcare System decided to find out.