Table 1.

Summary of advantages and disadvantages of commercially available live and killed Salmonella vaccines for poultry.

Live Vaccines	Killed or Inactivated Vaccines
Live vaccine strain can revert to its virulent form and spread to the environment and to humans	Vaccine antigens do not revert to virulence. No multiplication after administration
Live vaccine strain can interfere with the salmonellosis monitoring programs	No danger of vaccine contamination
Known to elicit both cell-mediated and humoral immune responses	Known to elicit a lower cell-mediated immunity
Adjuvants in live vaccines are not common	Adjuvants in killed vaccines are often needed
Known to elicit both cell-mediated and humoral immune responses and rarely require a booster	Known to elicit a shorter length of protection, so they are more likely to require boosters to create long-term immunity
Vaccines for breeders, broilers, and layers can be administered by spray or via feed or water	Vaccines for broilers and layers are administered intramuscularly, which can decrease the quality of the tissue, hence the value of the final product