IIRC, the "long influenza" was first noticed after the Spanish Flu pandemic. Cardio-pulmonary problems, and neurological problems,and a few odd problems. The writer Katherine Anne Porter survived the flu, but all of her hair fell out. It grew back white and was white for the rest of her days. President Woodrow Wilson caught the flu in Paris, while negotiating the Versailles treaty. He recovered, but it gave him a brain rot /brain fog. His behavior before and after the flu are like night and day, and had very unpleasant consequences, basically that the vindictive Clemenceau got his version of the treaty, which healthy Wilson vehemently had opposed, but sick Wilson gave in to, and we know what that treaty led to. Wilson's later stroke was probably a result of the Spanish Flu.
The Grauniad headline is misleading, but no surprise there. What should people call it? 'persistent infectious respiratory virus induced symptoms' or something equally silly? Tay-Tay has of course misunderstood both article and the report, both of which we all know she did not read.