Live Vaccine is a suspension of attenuated microorganisms (viruses or bacteria), administered for prevention of infectious diseases. Live vaccine provides a strong immune response and is valuable for stimulating mucosal immunity, which is especially important with respiratory disease. A killed vaccine is a vaccine consisting of virus particles, bacteria, or other pathogens that have been grown under controlled conditions and are killed as a means to reduce infectivity (virulence) and thus prevent infection from the vaccine. However, they tend to provide a shorter length of protection than live vaccines, and are more likely to require boosters to create long-term immunity.