I'm not talking about a full integration and dilution of the herd, just a series of interactions with other herds. I want to know at what point is your herd just part of a larger herd.
If we use this definition: Herd immunity occurs when a large portion of a community (the herd) becomes immune to a disease, making the spread of disease from person to person unlikely.
I think you're asking How do we define community?
Does it mean all those who live and eat and work mostly with each other? (eg, Jewish CH)
Or do we need to add to that those who join that physical space for shorter periods of working or eating, for example? (eg, cashier in CH grocery store who lives elsewhere, visitors who come just to shop)
If many individuals leave the community during the day for work, for example, can we still refer to the original community as having herd immunity, or does community need to be defined as the original community, plus all those within physical proximity of places of work and public transportation? (eg, CH plus the rest of NYC)