A team of researchers -- Nathanael Fillmore, Jennifer La, Chunlei Zheng, Shira Doron, Nhan Do, Paul Monach, Westyn Branch-Elliman -- recently conducted a study of how pandemic hospitalization numbers have been calculated thus far. They write:

Since the early days of the pandemic, COVID-19 hospitalizations have been used as a measure of pandemic severity. However, case definitions do not include assessments of disease severity, which may be impacted by prior vaccination.

In a September 13 article, David Zweig of The Atlantic writes "From the start, COVID hospitalizations have served as a vital metric for tracking the risks posed by the disease." Indeed, last winter, The Atlantic also described hospitalizations 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 the Westyn Branch-Elliman et al study of hospitalization records, released as a preprint and not yet formally peer reviewed, suggests the meaning of this measurement "can easily be misinterpreted—and that it has been shifting over time."

According to The Atlantic author Zweig, 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." 

And that, of course, makes such generalized hospitalization numbers less interesting or useful. So what can be done going forward?

Per Shira Doron, an infectious-disease physician and hospital epidemiologist at Tufts Medical Center and one of the study’s co-authors thinks “we should refine the definition of hospitalization. Those patients who are there with rather than from COVID don’t belong in the metric.”

Read the complete article at The Atlantic or review the study.