CDC Director Robert Redfield’s congressional testimony on September 23, 2020, immediately caught my attention. I watched in disbelief as Redfield told Congress that “more than 90 percent of the population”—more than three hundred million people in the US—remains susceptible to the illness.
The statement was based on incomplete and outdated data, as well as an apparent lack of understanding of the literature, and it struck me as one of the most erroneous and fear-inducing proclamations of any public health official to that moment. Approximately two hundred thousand Americans had already died from COVID; the last thing the public needed was an exaggeration of the future risks, implying to some that ten times that number could still die.
First of all, the numbers didn’t add up. At that point, confirmed cases in the US already totaled approximately seven million, and the CDC itself had estimated that approximately ten times the number of confirmed cases, a very conservative estimate, were likely to have had the infection. A Stanford seropositivity study back in April had shown that confirmed cases underestimated the total infections by a factor of approximately forty times. It made no sense that only 9 percent, or thirty million Americans, had been infected.
Second, the 9 percent calculation was blatantly wrong. That number came from antibody testing by the states. I looked at the CDC website myself, and sure enough, the data was based on antiquated testing from several states.