Question

why is it difficult to develop vaccine for some diseases.Also name their casual organisms​

Answer 1

Answer:

As a rule, if a disease normally leaves even a few survivors who are completely disease-free and immune for life, a vaccine against that disease is possible. “Natural infection is the mother of all vaccines,” said Dr. Anthony S. Fauci, director of the National Institute of Allergy and Infectious Diseases.

Smallpox meets the criteria; H.I.V., malaria and tuberculosis do not. H.I.V. mutates as fast in one day as flu does in a year; it also survives by splicing its DNA into the very immune cells that hunt it.

TB bacteria can survive even when “walled in” by white blood cells.

And malaria, a shape-shifting parasite, never triggers lifetime immunity. People who survive repeated bouts get less sick each time, but that immunity disappears if they move out of the malarial region. If they return, the first mosquito bite may kill them.

Answer 2

Explanation:

it difficult to develop vaccine for some deseases because some disises may contained very harmfrul