The problem is, "natural immunity" from a previous Covid infection varies greatly from person to person and we have no idea how long it lasts. I have an autoimmune disorder, so I was quick to get double vaccinated (also Moderna), then a month after my second vaccination, I was infected by a single exposure-literally, the one person who I was even remotely close to for 10 min infected me when he was setting up my new ISP. Sick as a dog for 2 weeks, almost went to the hospital, but I'm not the hospital type, so I held off. Anyway, I just got my 3rd Moderna shot yesterday and had a strong reaction to it, where I had ZERO reaction to the first two, so I'm finally hopeful I've gotten a decent immune response. There have been some good studies looking at natural immunity from infection, vs, vaccine immunity, AND BOTH together, and the very best protected people are the ones who got two vaccinations after first having a covid infection. I'm 100% convinced that everyone needs to get vaccinated regardless of previous infection. Delta is bad enough and there is already a new variant of concern brewing in South Africa with significant capabilities to evade our current vaccine-Delta is just so dominant it hasn't spread much yet.