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there are two type of vaccines
1.live or activated
2.dead or inactivated
simple concept is we refrigrate live vaccine ,,Unlike conventional protein-based vaccines, DNA vaccines are inexpensive to
produce, don't require refrigeration and can be stored for a long time.inactivated vaccines by killing the disease-causing microbe with chemicals, heat, or radiation
. Such vaccines are more stable and safer than live vaccines: The dead microbes can’t mutate back to their disease-causing state. Inactivated vaccines usually don’t require refrigeration, and they can be easily stored and transported in a freeze-dried form, which makes them accessible to people in developing countries. as we have limitation of words here please visit http://www.niaid.nih.gov/topics/vaccines/understanding/pages/typesvaccines.aspx for full description.hope you are satisfied with this.
take care payal