Pneumococcal diseases are caused by Streptococcus pneumoniae, a gram-positive bacterium responsible for over 50% of cases of community-acquired pneumonia and a leading cause of invasive pneumococcal disease (IPD), which encompasses bloodstream infections, bacteremic pneumonia, osteomyelitis, and meningitis, as well as non-invasive, mucosal pneumococcal disease (NIPD) such as acute otitis media, sinusitis, conjunctivitis and non-bacteremic pneumonia.