What is a “live strain vaccine?”

These kinds of vaccines, which include the Zostavax Shingles Vaccine, are also technically referred to as “live attenuated vaccines.” They introduce a weakened strain of the pathogen into the patient’s body in an effort to help the patient’s immune system develop an effective resistance to stronger, more virulent strains of the pathogen. These vaccines are different from inactivated (or “killed”) vaccines which introduce pathogens that have been grown and killed in a culture to the patient.