> So you can become more immune to next year’s colds by being exposed to many of them in present? I can't tell if your being genuine. Colds aren't like the fl

> So you can become more immune to next year’s colds by being exposed to many of them in present? I can't tell if your being genuine. Colds aren't like the flu. The flu tends to surge in a way that has a semi-predictable set of strains. The annual flu shot is largely an educated guess on which strands of the flu are going to be most common that year. There are dozens (hundreds?) of viruses that are responsible for causing colds all over the world. Just by the nature of how viruses spread and survive in a population, viruses strains tend to stay somewhat regional. You'll build immunity to the cold viruses common in your region, but you won't "pre-build" immunity to cold viruses from other areas. Overtime, though, virus strains permeate to other areas. People work together, people travel, etc, etc, etc. That means there's almost always a new "cold virus" that you can get exposed to. For example, if you dropped 100 people on an island and isolated them, they may all transmit cold viruses among them - but over time colds would disappear on that island. Everyone would have caught every possible cold that was brought to the island. The virus might actually hang around in the population, but people would have immunity to it and not get sick. However, if you just started dropping random people on that island, two things would happen: (1) Those people would likely bring new colds to the island, which everyone on the island might get (2) The island people might give the newcomers their colds ----- Part of the reason people get sick so often when flying is because they come into contact with a LOT of people who have exposure to different virus pools.