Even as covid-19 continues to dominate the public health spotlight, our old friend the flu is showing up with some new surprises. This year’s flu season is not following the usual bell curve pattern, as an NBC graphic illustrates, where cases peak around January and February and then fall toward the end of April. Instead, the flu has kept up its pace into May.

Things were on a relatively normal trajectory until about 10 weeks in, when cases declined and leveled off. By March, cases started to rise and peaked at about 10% of all tests coming up positive for the flu by April. The flu has now lingered into May, though overall cases are still low compared to the average flu season before covid-19.