Direct effectiveness of pneumococcal polysaccharide vaccine against invasive pneumococcal disease and non-bacteremic pneumococcal pneumonia in elderly population in the era of pneumococcal conjugate vaccine: A case-control study

摘要

Background: While herd effects and serotype replacement by childhood pneumococcal protein conjugated vaccines (PCVs) continues to accumulate worldwide, direct effectiveness of 23-valent pneumococcal polysaccharide vaccine (PPV23) against pneumococcal diseases in the elderly has been challenged. We estimated the direct effectiveness of PPV23 in the elderly population.