Live attenuated vaccines

Modified functioning virus or bacterium that can replicate in the patient's body but does not cause disease.

• Similar to an infection with a “wild” pathogen and induces a cellular and humoral immune response.

• Specific B-cells against an antigen are formed, which induces a potent, lifelong immune response

• Oral vaccine or subcutaneous/intramuscular injection in children > 12 months

• Not indicated in children < 9 months (the rotavirus vaccine is an exception, which is first given at 6 weeks of age)

• Second dose usually recommended to “catch” non-responders (not as a boost)

• Multiple live vaccines can be given simultaneously, but if given at different times they should be at least 4 weeks apart to avoid possible interference.

• May be administered simultaneously with inactivated vaccines

• MMR: prevents measles, mumps and rubella infections

• Varicella: against varicella-zoster virus (VZV)

• Zoster: prevents reactivation of latent VZV (i.e., shingles)

• Yellow fever

• Rotavirus

• Influenza (intranasal)

• Smallpox

• Adenovirus

• Oral polio, Sabin (no longer available in the US)

• BCG

• Typhoid (oral, Ty21a)

“TYler And Paul Burnt their INFamous ROasted YELLOW-RUBy CHICKEN MEAt Very MUch”: TYphoid, Adenovirus, Polio, BCG, INFluenza, ROtavirus, YELLOW fever, RUBella, CHICKENpox, MEAsles, Varicella, and MUmps are live attenuated vaccines.

• Very rarely, live attenuated vaccines may become virulent again and are thus often contraindicated in immunodeficient individuals and pregnant women .

• HIV-positive individuals can be vaccinated with live attenuated vaccines (e.g., MMR and varicella) if their CD4 cell count is ≥ 200 cells/mm3.

• Adenovirus vaccine is given in its nonattenuated form to military recruits.