Are virologists a type of doctor, or are they only scientists? and what are some fields related to immunology and virology?

Scientist: There is no recognized board of virology but it can best be fitted into the sub-specialty of Infectious Disease (under Internal Medicine). As for immunology, the specialty board I know of is the American Board of Allergy and Immunology. However most specialists would practice primarily clinical allergy or immunology with some cross-over. Most immunologists are more geared towards research.