Update: Even after doing the intelligent updater, my NAV continued to say that I was only running the 1/18 definitions. I finally checked my activity log and saw that indeed, since I ran the Updater, NAV has been catching “W32.Novarg.A@mm“ which is one of the names of this virus.

I could not figure out why my latest virus definitions kept saying 1/18 even after I manually ran live update. Here's why!!

LiveUpdate
LiveUpdate is the easiest way to obtain virus definitions. These virus definitions have undergone full quality assurance testing by Symantec Security Response and are posted to the LiveUpdate servers once each week (usually Wednesdays) unless there is a major virus outbreak. This is the easiest option for most home and small business users, and it provides a very high level of protection along with ease of use.

Intelligent Updater
Intelligent Updater virus definitions have undergone full quality assurance testing by Symantec Security Response. They are posted on U.S. business days (Monday through Friday). They must be downloaded from the Symantec Security Response download virus definitions page and installed manually.