What general immunization principle should the nurse understand regarding community (herd) immunity?

Community (herd) immunity is the general principle that when a sufficiently high proportion of a population is immune to a contagious disease — typically through vaccination — the disease spreads less easily, which provides some indirect protection even to people who are not immune (such as those who cannot be vaccinated for medical reasons). It is directly related to vaccination rates and does not eliminate the need for individual vaccination. Understanding herd immunity is a standard public-health and health-promotion concept. (This reflects a general principle; specific vaccine recommendations and coverage thresholds change over time and must be verified against current authoritative guidance and NCLEX prep materials.)