[Organizers] Acquired Immunity Policy Examples

We're considering a topic which has been raised to us a few times from prospective participants. To this date, we have maintained a straight vax + boost requirement for our series. I'm interested in examples of group COVID policies providing for participation of individuals who do not otherwise meet published vaccination requirements but have acquired potential immunity due to recent infection. Effectively, having acquired immunity through infection substituting as a form of vaccination. In particular: what are the qualifications and/or proof requirements and the duration of the allowance for vaccination substitution you use, if any? Substitution for any/all vax requirements or simply as a booster equivalent in some form? Thanks in advance for your help and links to any written policies. I'd greatly prefer if we can keep this thread focused on this particular topic and appreciate all civility. Should you wish to raise a tangential issue, please revise the subject line to fork the thread.