Wow, ok. Natural immunity can cost you dearly, if you survive. My unvaccinated parents in their mid-sixties nearly did not survive delta last year and still have ongoing cognitive issues 10 months later. Mobility issues lasted several months and they still are unable to work.
Natural immunity to me means you have had Covid already. Best to your parents. Sounds like they did not previously catch covid before delta.
I'm just saying this focus on boosters is false and misleading, particularly if you have already had covid, ie natural immunity.
I think your suppositions about infection-based immunity are a bit out of date. In review articles I've read, infection-based immunity was indeed associated with a stronger immune response than a two-shot MRNA vaccine during the delta wave. However, it was inferior during OG Covid and Alpha, and comparable to unboosted MRNA during Omicron. Boosted vaccines were initially shown to be significantly better than infection-based immunity during the first part of Omicron, though I haven't done another literature survey to see how those numbers have evolved through the subvariants. However, I did see this in a recent publication of Nature:
https://www.nature.com/articles/s41586-022-04865-0"Limited cross-variant immunity from SARS-CoV-2 Omicron without vaccination"
“In the unvaccinated population, an infection with Omicron might be roughly equivalent to getting one shot of a vaccine,” says Melanie Ott, MD, PhD, director of the Gladstone Institute of Virology and co-senior author of the new work. “It confers a little bit of protection against COVID-19, but it’s not very broad.”
“This research underscores the importance of staying current with your vaccinations, even if you have previously been infected with the Omicron variant, as you are still likely vulnerable to re-infection,” says co-senior author Jennifer Doudna, PhD, who is a senior investigator at Gladstone, a professor at UC Berkeley, founder of the Innovative Genomics Institute, and an investigator of the Howard Hughes Medical Institute.