Answer:Primary source would be a CDC official like Dr. Fauci, or a quote from a doctor on the frontlines for a hospital. Secondary would be studies done or articles/newspapers that look at issues and use those experts as information in their writings.
Explanation: These are primary and secondary sources, assuming you don't mean causes. Primary- firsthand accounts of something. Secondary- it is written about later and the person is not really directly there at an event.