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Hospitals have seen only a few silver linings throughout the COVID-19 pandemic — a dramatic drop in the flu and other respiratory illnesses among them. But a year without the flu could actually be a problem for vaccine developers and disease forecasters, as well as for people who've gone a whole year without reinforcing their immune system against respiratory diseases, The Atlantic reports.

As 2020 ended and the pandemic began overlapping with the start of a typical flu season, the Mayo Clinic was among hospitals that began testing patients with respiratory symptoms for both COVID-19 and the flu. But among the 20,000 flu tests it conducted between December 1 and February 1, zero came back positive. The Centers for Disease Control and Prevention similarly reported a mere 0.2 percent flu positivity rate among 800,000 lab samples reported nationwide.

While the flu dropoff was great news for overwhelmed hospitals, it hasn't been helpful for scientists who monitor the flu's constant mutations. Virologists and vaccinologists typically pore through mountains of samples from around the world to predict what the next year's dominant strain will look like and make vaccines to counter it, Stacey Schultz-Cherry, a virologist and immunologist at St. Jude's Children's Hospital, tells The Atlantic. A year without exposure to the virus could also prove problematic for the human immune system, and especially for children who have been exposed to few, if any, varieties of the flu.

Scientists may not have the best view of what's going on with the flu right now. But Florian Krammer, a virologist and flu expert at the Icahn School of Medicine at Mount Sinai, suggested two possibilities. Hopefully, a lack of flu circulation "could end up throttling the circulating strains — possibly even taking one out of commission entirely," The Atlantic writes. But it's also possible the flu family tree could split in two, creating a strain scientists don't even know about until it goes viral. Read more at The Atlantic.