The masters think a slave who chooses to work during his time off doesn't deserve the time off, and a slave who doesn't work to save enough throughout the year to buy whiskey for the holidays is considered lazy.
An adjuvant is a substance added to some vaccines to enhance the immune response of vaccinated individuals. The aluminum salts in some U.S. licensed vaccines are aluminum hydroxide, aluminum phosphate, alum (potassium aluminum sulfate), or mixed aluminum salts.
An attenuated vaccine is a vaccine created by reducing the virulence of a pathogen, but still keeping it viable (or live). Attenuation takes an infectious agent and alters it so that it becomes harmless or less virulent. These vaccines contrast to those produced by killing the virus (inactivated vaccine).