Notes
Live vaccines contain living pathogens. These pathogens
invade cells within the body and use those cells to produce
many copies of themselves, just as their more harmful
counterparts would. The "similar pathogen" and "attenuated"
vaccines discussed in this feature are examples of live
vaccines. Although these vaccines trigger a full immune
response, there is a small risk of the viruses within
evolving into more-virulent strains. Non-live vaccines
contain agents that do not reproduce in the body. "Killed,"
"subunit," and "toxoid" are examples of non-live vaccines.
These vaccines trigger a partial immune response. Genetic
vaccines are non-live vaccines that trigger a full immune
response.
The procedures outlined in this feature have been greatly
simplified. Also, some steps are meant to show what is done
but not how. For example, a gene cannot be plucked out of
DNA using tweezers, and there's no box-like device called a
purifier that can extract toxins from bacteria as well as
viruses from pus.
