All are true about herd immunity except:
|A||Depend on the presence of sub clinical infection|
|B||Herd immunity is constant|
|C||Depends on presence of alternative host|
|D||Depends on immunization status of herd|
Herd immunity is the level of resistance of a community or group of people to a particular disease or It is the group protection beyond that afforded by the protection of immunized individuals.
Elements which contribute to herd immunity are
- Occurrence of clinical and sub clinical infection in hard
- Immunization of the herd
- Herd structure
4. Herd structure is never constant it varies because of new birth, death and population mobility. An ongoing programme will keep up the herd immunity at a very high level.
In case of diphtheria and polio, herd immunity is very important.
However it does not protect the individual, in tetanus.