The CDC just updated their information a few days ago. Immunity was originally not a thing at all. It was believed and reported that even if you got covid, you could get it again immediatley. There was even a suggestion that you could "reinfect" yourself via 3rd party or even with items previously contaminated by you during latency. Then it to 3 months or less. Again it evolved and went from 3 months to 8 months. Today there was an update saying there is good evidence that immunity lasts well beyond that figure, although they cannot say for certain at this time.It evolves and as more data comes in, the information gets refined and filtered down. It never made any sense, from an immunological standpoint, that immunity would only last for 3 months. Once our immune systems come across something and beats it, the cell memory recognizes it and mitigates it should you come across it a second or third time. If you are healthy without other conditions taxing your immune system, you will shake it off with nary a symptom. The idea that an illness that is as severe as covid; epic enough to close society down and run us into our homes for a year +, could be then forgotten by the human body, without reason or pathological explaination never sat right. To be honest, I have yet to hear any legitimate source explain exactly how one can be infected and then re-infected 3 months later....probably because it's now been proven to be impossible. So...we sit at the 8-10 month mark. It's all but certain that in a few months it will be extended further and further and further till it is eventually discovered that once infected immunity lasts a lifetime or requires a booster vaccination about a decade or so later. Due to the fluidity, the misinformation and the discovery of new information daily there is no way to be certain today, however I believe we will at some point be able to say definitively.