* Fastest and easiest method
* A virus is taken and killed in the laboratory, the dead one is put in a person
* Body doesn't detect it, hence a medicine is given with it ⇒ which detects the virus
* For bacteria no medicine needs to be taken as antibodies will be made
* Side effects: What if dead virus re-alives
* Only the antigen instead of the full virus/bacteria is used
* Anti-toxins made in the lab and put in the body they remain as memory cells
* This method is rarely used as not many bacteria produce toxins
* A long time is spent in research and then a cell is made to replicate the antigen(looks)
* A non virulent strain of the organism is grown
* Removing DNA sequence from virus