Our Most Reliable Pandemic Number Is Losing Meaning

 

Justin Paget / Getty; The Atlantic

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. 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. Presumably, hospitalization numbers provide a more stable and reliable gauge of the pandemic’s true toll, in terms of severe disease.

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. 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.

According to the researchers, 40 to 45 percent of the hospitalizations that they examined were for patients in the latter group. The authors of the paper out this week took a different tack to answer a similar question, this time for adults. Instead of meticulously looking at why a few hundred patients were admitted to a pair of hospitals, they analyzed the electronic records for nearly 50,000 COVID hospital admissions at the more than 100 VA hospitals across the country. Then they checked to see whether each patient required supplemental oxygen or had a blood oxygen level below 94 percent.

From mid-January through the end of June 2021, however, that number rose to 48 percent. In other words, the study suggests that roughly half of all the hospitalized patients showing up on COVID-data dashboards in 2021 may have been admitted for another reason entirely, or had only a mild presentation of disease. This increase was even bigger for vaccinated hospital patients, of whom 57 percent had mild or asymptomatic disease. Among the limitations of the study is that patients in the VA system are not representative of the U. The study did run through June 30, however, when the Delta wave was about to break, and it did not find that the proportion of patients with moderate to severe respiratory distress was trending upward at the end of the observation period.

The idea behind the study and what it investigates is important, says Graham Snyder, the medical director of infection prevention and hospital epidemiology at the University of Pittsburgh Medical Center, though he told me that it would benefit from a little more detail and nuance beyond oxygenation status. But Daniel Griffin, an infectious-disease specialist at Columbia University, told me that using other metrics for severity of illness, such as intensive-care admissions, presents different limitations. For one thing, different hospitals use different criteria for admitting patients to the ICU. One of the important implications of the study, these experts say, is that the introduction of vaccines strongly correlates with a greater share of COVID hospital patients having mild or asymptomatic disease.

«People ask me, ‘Why am I getting vaccinated if I just end up in the hospital anyway?’» Griffin said. «But I say, ‘You’ll end up leaving the hospital. » At the same time, this study suggests that COVID hospitalization tallies can’t be taken as a simple measure of the prevalence of severe or even moderate disease, because they might inflate the true numbers by a factor of two. «As we look to shift from cases to hospitalizations as a metric to drive policy and assess level of risk to a community or state or country,» Doron told me, referring to decisions about school closures, business restrictions, mask requirements, and so on, «we should refine the definition of hospitalization.

Those patients who are there with rather than from COVID don’t belong in the metric».

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Source: David Zweig | The Atlantic