Pneumococcal vaccines for prevention of adult pneumonia.

Streptococcus pneumoniae, pneumococcus, is one of most important bacterial pathogens in adult community-acquired pneumonia. Although it can cause a variety of illness including invasive diseases (IPD), pneumonia has a greater impact than IPD from the perspective of health economics. 23 valent pneumococcal polysaccharide vaccine (PPSV23) and 13 valent pneumococcal conjugate vaccine (PCV13) have been recommended for people ≥65 years old until recently based on evidence in preventing IPD and pneumonia. Because the introduction and dissemination of PCVs for infants and its effects on herd immunity have led 'serotype replacement' in adult IPD and pneumococcal pneumonia since the 2000s, serotypes targeted by vaccines have sifted accordingly. With the availability of PCV21 this year, in addition to PCV15 and PCV20, vaccine prevention strategies for adult pneumococcal pneumonia need to be reconsidered. In this narrative review, we discuss current and future challenges regarding pneumococcal vaccines to prevent adult pneumococcal pneumonia.