Ok whoa. I’ve never heard of “immunity debt” but you can’t have it both ways. In one hand you can’t be pro-vaccine and then claim that catching the actual disease doesn’t confer the same immune response after it is gone. They literally work by the same biological mechanism. I mean vaccines aren’t magic and are not the only way to game immunity to certain diseases. They are safer for sure but your friend has a point. The immune system isn’t something that gets “used up” over time. Short of being immune compromised you don’t “run out” of your immune system. It can be overwhelmed at times but it does it stronger and more adapted the more pathogens it is exposed to…. Yeah because that’s literally what vaccines do.