It seems as though Covid is in the news less and less these days but now just as everyone lets their guard up, infections begin to rise again, striking a handful of people I know around me down for a few days with mild flu like symptoms and thankfully that has been all. It seems like everyone I know has had Covid, even some more than once over the past 2.5 years. As of April 2022 there have been 500+ recorded cases of Covid according to this chart by NY Requirements about the fastest spreading viruses in world history. The Omicron variant of Covid-19 ranks 4th on this entire list with an R0 of 10.5. The R0 stands for the average reproductive number, the higher the number the more people will likely become infected by transmission. Measles is in the #1 spot on the chart. Still affecting 9 million people annually even with a vaccine, measles has an R0 of 15. Read on to see other fastest spreading viruses in the world.