I have my suspicions that it was here by Xmas, as well, but I keep coming back to how contagious it is now versus that, essentially, mini-outbreak over winter. If that was here then, why didn't it spread like it's spreading now? People who were sick were at Xmas parties, vacation, visiting family, including grandma and grandpa. Yet the anecdotes of people who think they had it are limited. It was certainly a year attributed to much higher numbers of flu cases, including people dying from it that had no underlying reason to have died from it. But still, not in the numbers we are seeing right now, even with the 'shelter in place' happening all over the world.