Can you explain exactly how it’s moral to prevent an otherwise healthy person from mixing with the elderly (who are free to be vaccinated and wear PPE if they f

Can you explain exactly how it’s moral to prevent an otherwise healthy person from mixing with the elderly (who are free to be vaccinated and wear PPE if they feel at risk) in public settings, unless they will accept a medical intervention with a 1/3000 risk of a serious adverse event to themselves?