1. What’s the difference between an “infectious” vaccine and a “noninfectious” vaccine?
Vaccines referred to as “infectious” include those in which the immunizing virus/bacteria replicates within the host after administration. All attenuated viral and bacterial vaccines, including virus-vectored recombinant vaccines, are infectious (e.g., modified-live canine distemper virus, intranasal and oral B. bronchiseptica, and the recombinant canine distemper virus (rCDV) vaccines).
The immunizing virus/bacteria in a “noninfectious” vaccine is not capable of replicating within the host after administration. All inactivated (killed) viral vaccines (e.g., rabies, CIV) and bacterial vaccines are noninfectious (e.g., leptospirosis, Borrelia burgdorferi [canine Lyme disease], canine influenza virus, and parenteral B. bronchiseptica vaccines).9