What is a potential downside of live attenuated vaccines?

• A. They do not produce an immune response
• B. They must be stored and handled carefully
• C. They never interfere with circulating antibodies
• D. They are always safe in pregnancy

Answer: (B)

Live attenuated vaccines contain a weakened form of the organism, chosen because they provoke a strong, lasting immune response by closely mimicking natural infection. However, their potency relies on keeping the organisms alive and functioning, which means they are highly sensitive to storage and handling. If these vaccines are not kept at the proper temperatures and protected from improper handling, their potency can drop, leading to reduced immunogenicity or a failed immunization. This need for strict cold-chain storage and careful preparation is a real practical drawback, especially in settings with limited refrigeration or complex handling steps. About the other points: these vaccines do typically induce an immune response; they can be affected by preexisting circulating antibodies in some contexts; and they are not universally safe in pregnancy, so safety in pregnancy is not guaranteed.