As far as I can tell, natural immunity relates to the variant. If you had Alpha, and then you encounter Delta, your natural immunity may help you a little, but

As far as I can tell, natural immunity relates to the variant. If you had Alpha, and then you encounter Delta, your natural immunity may help you a little, but possibly not enough to prevent hospitalization, since Delta is 2.5x more likely to cause a serious hospitalization. So natural immunity counts, but maybe not against powerful variants. And we should be doing whatever we can to prevent people from becoming infectious and spreading it further.