Throughout human history, as we spread across the world we have had infectious diseases as a constant companion. Outbreaks continue to happen, even more frequently in our modern era. First, I discuss a timeline over the last 2000 years and chat about some of histories most deadly pandemics, including the biggies such as Black Death (Bubonic Plague); with 200 million dead (30-50% of Europe); smallpox killing 90% of Native Americans, and the Spanish flu. Next I discuss what we know about seasonal cycles of many infectious diseases, and then some recent papers considering whether Covid-19 may be seasonal, perhaps weakening as we head to Northern Hemisphere summer.