@Splinty If common cold and flu are viruses, and belong to Corona family. We know they effect you once every season or twice every year.
I am thinking Corona may not effect those who already had cold or flu this season.
In general...
Viruses infect you. When they do they trigger an immune response. This first response is generic. This is fever and some other parts of your immune system cells attacking the invader. Some hand off happens and your body figures out the exact protein and we actually develop antibodies to attack this specific virus. It's kind of cool how complicated it is and how often it usually works pretty well.
In the case of Corona viruses that cause our common colds some people in part lifelong immunity. That is you see it once you make these antibodies and if you ever see that guy again your body will ramp up the special forces specifically for that virus really quickly and you essentially will never get a full infection for the rest of your life.
Other people this doesn't seem to be the case. Some people seem to have antibodies, that is immunity to that specific virus, for 5 or 10 years but then these antibodies kind of fade away. It's like your body sort of forgets it seen it before and just decides not to spend energy creating those antibodies for the guy it hasn't seen for so long. So those people can get infected with the same virus that got them as a kid.
Each virus has different protein structures let alone what's inside of those protein structures. because of this you can be infected with multiple different coronaviruses and it's usually unlikely that your existing antibodies will be good for the next virus even though they're in the same family.
Because of that this current Corona virus that has never been seen by any human on the planet and all of human history is going into a population that has no special forces antibodies. We only have our generic immune response of fever and generalized cells. We then have to build our special forces to kill it. Some people tend to do this very well. We see children do this very well. Others do not. This new organism kicks off a chain of events that makes us go a little bit overboard and trying to fight it and that overboard fight kicks off a chain reaction cascade that gets us pretty sick.
so no I don't think there's any evidence right now nor I think you would expect that being infected with Corona viruses as a kid, as All of us have been, will give us immunity to this new Corona virus.