Pneumococcal polysaccharide vaccine (PPSV23) is best categorized as what type of vaccine?

The pneumococcal polysaccharide vaccine (PPSV23) is categorized as an inactivated polysaccharide vaccine. This type of vaccine is designed to protect against infections caused by certain bacteria, specifically Streptococcus pneumoniae in this case. The PPSV23 vaccine contains purified polysaccharide antigens from 23 different serotypes of the pneumococcus bacteria. These polysaccharides trigger an immune response, leading the body to produce antibodies that offer protection against future infections by these specific serotypes.

Polysaccharide vaccines, like PPSV23, operate by eliciting a T-cell independent immune response. This means that while they stimulate B cells to produce antibodies, they do not significantly invoke the helper T cells that are often stimulated by other types of vaccines, such as proteins (inactivated conjugate vaccines). The inactivation aspect here refers to the fact that the vaccine does not contain live pathogens that can cause disease, making it safe for immunocompromised individuals.

In the context of the other types of vaccines listed in the choices, an inactivated recombinant vaccine utilizes genetically modified organisms to produce antigens, while a live attenuated vaccine includes weakened forms of the live virus or bacteria, and an inactivated conjugate vaccine typically uses