This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Epidemiology, Subject name: Social & Preventive Medicine
Herd immunity provides protection to- 
Select and explain. 
A. Immunized persons, B. Non immunized persons, C. Both, D. None
B: Non immunized persons
Answer: B: Non immunized persons 
Explanation: Herd immunity describes a type of immunity that occurs when the vaccination of a poion of the population provides protection to unprotected individuals provides an immunological barrier to the spread of disease in human herd elements-(a) occurence of clinical and sub clinical infection in the herd ( b ) immunization of the herd ( c) herd structure (refer pgno:102 park 23 rd edition).