Chuck, in the same vein as Babar's question, I'd love to hear your thoughts on this:
Essentially, it's a question of dueling experts, studies and reports, about natural immunity.
First, there are many reports such as this one, saying many people (here, 36%) of covid infection survivors demonstrate little or no lasting measurable immunity:
https://wwwnc.cdc.gov/eid/article/27/9/21-1042_article
On the other hand, we have articles from presumably bona fide researchers such as this "perspective piece" in WaPo by a Hopkins professor, suggesting natural immunity should be more of a policy driver than it is, and that natural immunity appears to be as good or better than vax-derived immunity as relates to mandates.
https://www.washingtonpost.com/outlook/2021/09/15/natural-immunity-vaccine-mandate/
I suspect that the issue is in what types of infections (systemic versus minor upper respiratory tract, symptomatic versus asymptomatic, etc) are being used as a basis for comparison.
Edit: And crucially, the need to verify serologic response versus just a positive PCR test is ke.
However, I would love your input on these issues