Scientific American asks experts in medicine, risk assessment and other fields how to balance the risks of COVID with the benefits of visiting public indoor spaces
As COVID cases declined across the U.S. in recent months and mask mandates were lifted, more people returned to restaurants, concert halls and offices maskless. But the novel coronavirus’s Omicron subvariant BA.2—which caused another wave in Europe and China—and related variants threaten to reverse that progress here. Earlier this month dozens of attendees tested positive for COVID after attending a dinner in Washington, D.C.
In general, people should discuss personal COVID risk with their doctor; it depends, in part, on which medications they take. Ethan Craig, a rheumatologist at the University of Pennsylvania, cares for patients who are immunosuppressed because of disease or medication and studies COVID risks in that population. One such immunosuppressive drug, rituximab, “knocks out your ability to make antibodies against new viral exposures and impairs your ability to make a response to a vaccine,” he says.
But Baruch Fischhoff, a professor of engineering and public policy at Carnegie Mellon University and an authority on how to communicate health risks, cautions against using risk-risk comparisons to make choices without fully considering benefits or unquantified risks. Employers may also misuse such comparisons to compel employees to accept certain risks on the job, which is not exactly a choice.
Because of these large uncertainties in test coverage, Gerardo Chowell, a professor of mathematical epidemiology at Georgia State University, prefers to look at the general trend in daily COVID cases, hospitalizations and deaths, or percent positive. “When the trend is going up, you’re seeing the transmission chains expand,” Chowell says. “That means that the reproduction number”—the expected number of secondary infections from each infected person—“must be greater than one.