[2] The polysaccharide antigens were used to induce type-specific antibodies that enhanced opsonization, phagocytosis, and killing of Streptococcus pneumoniae (pneumococcal) bacteria by phagocytic immune cells.

A significant breakthrough affecting the burden of pneumococcal disease was the licensing of a protein conjugate heptavalent vaccine (PCV7) beginning in February 2000.

In Canadian patients infected with HIV, the vaccine has been reported to decrease the incidence of invasive pneumococcal disease from 768 per 100,000 person–years to 244 per 100,000 patient–years.

[4] Because of the low level of evidence for benefit, 2008 WHO guidelines do not recommend routine immunization with PPV-23 for HIV patients, and suggests preventing pneumococcal disease indirectly with trimethoprim–sulfamethoxazole chemoprophylaxis and antiretrovirals.

[14] The most common adverse reactions (reported in more than 10% of subjects vaccinated with pneumococcal polysaccharide vaccine in clinical trials) were: pain, soreness or tenderness at the site of injection (60.0%), injection-site swelling or temporary thickening or hardening of the skin (20.3%), headache (17.6%), injection-site redness (16.4%), weakness and fatigue (13.2%), and muscle pain (11.9%).