How do live attenuated vaccines differ from inactivated vaccines?

Live attenuated vaccines contain a version of the pathogen that can still replicate a little, but not enough to cause normal disease in healthy people. Inactivated vaccines contain germs that have been killed or disabled so they cannot replicate at all. Because live vaccines behave more like a natural infection, they often produce longer-lasting immunity with fewer doses. Inactivated vaccines are generally safer for people with weakened immune systems, but they may need boosters or adjuvants to strengthen the response. Examples include the oral polio vaccine, which is live attenuated, and the injectable polio vaccine, which is inactivated.