Every disease has its super spreaders, this poster is just a good example of why we should cancel everything and be careful, since there is at least one person out there with no understanding of risk and disease epidemiology. There are likely to be more, and the less chances we give them to put us and vulnerable populations in harm's way, the better. If we knew everyone would react appropriately we wouldn't need drastic action, but this is a perfect example of why we need to act fast.