Answer:
Herd immunity protects those individuals who are not immune to the disease because the number of susceptible individuals is reduced greatly.
Explanation:
The immunity provided by the major population which is immune to a particular contagious disease to some of the individuals of population which is not immune to the disease is called herd immunity.
Herd immunity is achieved when a large percentage of the population is vaccinated for that infectious disease for example herd immunity for measles requires 92-95% of the population to be vaccinated.
In this case, the disease is not able to cross the barrier of the immune population and so do not able to infect susceptible individuals.