Herd Effect vs Herd Immunity

Context: Plan for nationwide roll of covid -19 vaccine

Concept:

Herd Immunity: The proportion of subjects with immunity in a given population. When a vaccine is rolled out and increasing proportion of people get vaccinated, herd immunity level increases and decease frequency decreases in the vaccinated population.

Herd Effect is defined as the reduction of infection or disease in the unimmunized segment as a result of immunizinga proportion of the population.