Social network analysis (SNA) is increasingly a method of analysis for many fields. Epidemiology is fascinating, but before deciding to jump into a new field, think about how it may apply to your own sphere of interests.

Since you said you're a programmer, my advice would be to find or collect some data you are interested in, and play with Python's networkx.[1] For some starter data, check out Stanfords Large Network Dataset Collection.[2]

[1] http://networkx.lanl.gov/ [2] http://snap.stanford.edu/data/

(Why were people down-voting this? It looked like a sincere question.)