A century ago, the Flu Pandemic was bimodal. Its first peak was in late winter of 1917, before returning with vengeance in the fall-winter of 1918. COVID-19, too, has shown a seasonal variation, with its early peak last year and another rise now that seems to be fading away. So, some questions: Where do these viruses go? Do they leave at all? What makes them seasonal? Let’s explore.
