14/10/2025
Streptococcus pneumoniae, a major cause of pneumonia, meningitis, and bloodstream infections, can be prevented through vaccination. There are two main types of pneumococcal vaccines: pneumococcal conjugate vaccines (PCVs) and the pneumococcal polysaccharide vaccine (PPSV23). PCVs, like PCV13, are mainly given to infants, young children, and certain high-risk adults. They work by linking the bacterial polysaccharides to a protein carrier, which stimulates a stronger and longer-lasting immune response, including the development of immune memory. PPSV23, in contrast, contains purified polysaccharides from 23 pneumococcal strains and is primarily recommended for adults over 65 and people with chronic conditions or weakened immune systems. While it provides broad protection against many strains, it does not induce as strong immune memory as PCVs. Together, these vaccines form a complementary strategy to reduce the risk of invasive pneumococcal disease and serious complications.