Which of the following vaccines is classified as a live attenuated vaccine?

A live attenuated vaccine contains a version of the living virus or bacteria that has been weakened so it cannot cause disease in healthy individuals. When administered, live attenuated vaccines stimulate a strong immune response mimicking natural infection, which usually provides long-lasting immunity.

Varicella (VAR), which is the vaccine for chickenpox, is indeed classified as a live attenuated vaccine. It uses a weakened form of the varicella-zoster virus to protect individuals from developing chickenpox by helping the immune system recognize and respond to the virus if exposed in the future.

In contrast, the other vaccines mentioned do not fall into the live attenuated category. Hepatitis B vaccine, for example, is a recombinant vaccine and contains only parts of the virus, specifically the surface proteins, which means it does not contain live virus. Hepatitis A vaccine is an inactivated vaccine that contains killed virus particles. The recombinant zoster vaccine (RZV) is also not live but rather a recombinant vaccine that utilizes a non-live form of the virus to elicit an immune response against the shingles virus. This distinction is crucial when discussing vaccine classifications and their mechanisms of action.