What Happens When COVID-19 Collides With Flu Season?

At a February 26 press conference, President Donald J. Trump said of the novel coronavirus, “This is like a flu,” and expressed surprise that as many as 69 000 people in the US die of influenza every year. However, the ensuing 51⁄2 months have shown that coronavirus disease 2019 (COVID-19) is far deadlier and less predictable than seasonal influenza. Unlike influenza, COVID-19 does not appear to be seasonal, given the ever-increasing numbers of US cases this summer. So beginning this fall, the US for the first time will have to deal with a flu season wrapped in a global pandemic. Or, as the headline on a recent editorial by Edward Belongia, MD, and Michael Osterholm, PhD, MPH, described it, “a perfect storm.” Many questions remain about how flu season might affect the pandemic, and vice versa. For example, would coinfection with influenza worsen the course of COVID-19? Experts also aren’t certain whether influenza vaccinat ion could help protec t against COVID-19 or whether steps taken to mitigate COVID-19 will reduce the burden of the coming flu season. Some hints have come from preliminary research conducted in China, where influenza was still widely circulating when the first novel coronavirus infections emerged, and in the southern hemisphere, which is currently in the midst of its flu season. At least 2 things are clear: Quicker and more widely available testing is needed to distinguish between COVID-19 and influenza, which have similar symptoms, at least at first, but require different treatments. On top of that, a severe influenza season—the result of more virulent strains, inadequate vaccination rates, or a combination of both—coupled with a COVID-19 pandemic that shows no signs of abating, could overwhelm already taxed emergency departments and intensive care units. As pulmonary and critical care specialist Benjamin Singer, MD, wrote in a recent editorial, influenza and other causes of pneumonia represent the eighth leading cause of US deaths in nonpandemic years. “We can expect that the new reality of COVID-19 will only complicate the next influenza season,” Singer, of the Northwestern University Feinberg School of Medicine, concluded in his editorial.