This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Social & Preventive Medicine
All of the following are true about the Herd immunity for infectious diseases except - 
Select and explain. 
A. It refers to group protection beyond what is aforded by the protection of immunized individuals, B. It is likely to be more for infections that do not have a sub-clinical phase, C. It is affected by the presence and distribution of alternative animal hosts, D. In the case of tetanus it does not protect the individual
B: It is likely to be more for infections that do not have a sub-clinical phase
Answer: B: It is likely to be more for infections that do not have a sub-clinical phase 
Explanation: Ans. is 'b' i.e., It is likely to be more for infections that donot have a sub-clinical phase o Herd immunity is more for infections that have a subclinical phase, because by subclinical infection the individual develops immunity against that paicular infection and buildup herd immunity. o Herd immunity implies group protection beyond that afforded by the protection of immunized individuals. Significance of herd immunity Herd immunity predicts occurance of epidemics. o If herd immunity is sufficiently high the occurance of epidemics is highly unlikely. o Herd immunity may lead to elimination of the diseae : - i) Diphtheria and poliomyelitis may be eliminated by stepping up herd immunity. ii) Small pox was eliminated by elimination of source of infection and not by herd immunity.