What is the difference between a case-control study and a cohort study ? In your own words, how are R0 and herd immunity related to each other?

Infections disease( spillover)
Ignaz Semmel weiss is known for which of the following?
A. determining that contaminated medical equipment was causing child bed fever
B. developing a smallpox vaccine based on a cowpox variant

C. Shutting down the broad street pump
D. Discovered the association between draining swamps and preventing malaria
E. Created the germ theory
Provide a 1 sentence definition for the following:
Describe the epidemiological transition.

What is the difference between Public Health and Medicine?

What is the difference between a case-control study and a cohort study ?
In your own words, how are R0 and herd immunity related to each other?
Provide a 1 sentence definition for the following