Scientist at the CDC (Center for Disease Control) in Atlanta, GA are currently developing and testing new treatments and vaccines for the coronavirus. What kind of research are they conducting?

Applied research

Explanation:

The process of developing a new vaccine involves the use of known scientific theories to address specific problems. Here, the outcome of several basic research are put into use to arrive at a targeted outcome. This outcome/product can be continuously modified (if it shows early promise) until the desired effect is achieved and if no "promise" is discovered at critical points of this research, work on this theory (for this research) is suspended another theory is pursued.

This process (described above) in which scientists continuously develop new treatments and/or vaccines and continuously subject it to testing until the desired effect is achieved can be referred to as Applied research.