Question re. "vaccinated registrants should not count on capacity"

Hi!
I got a new requirement that vaccinated registrants should not count on the event capacity.

E.g. By the maximum von non-vaccinated registrants is 10. But vaccinated registrants have no limit. So the event could have 10 non-vaccinated + 5 vaccinated.
I tried it with Ticket Types but this plugin does not allow to force a choice between two ticket types. A registrant could book a ticket for vaccinated persons and one for non-vaccinated. Or is there an option to limit the maximum number of tickets for a combination of ticket types?

Any other idea how the requirement could be implemented?

Thanks.

Frank