Pneumococcal polysaccharide vaccine (PPSV)—known as Pneumovax 23 (PPV-23)—is the first pneumococcal vaccine derived from a capsular polysaccharide. 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. The pneumococcal polysaccharide vaccine is widely used in high-risk adults. As a result, there have been important reductions in the incidence, morbidity, and mortality from invasive pneumococcal disease. First used in 1945, the tetravalent vaccine was not widely distributed, since its deployment coincided with the discovery of penicillin. In the 1970s, Robert Austrian championed the manufacture and distribution of a 14-valent PPSV. This evolved in 1983 to a 23-valent formulation (PPSV23). A significant breakthrough affecting the burden of pneumococcal disease was the licensing of a protein conjugate heptavalent vaccine (PCV7) beginning in February 2000. Medical uses In the United States, PPSV is recommended for adults 65 years of age or older, adults with serious long-term health problems, smokers, and children older than two years with serious long-term health problems, affording protection for five years or more. The World Health Organization (WHO) recommendations are similar. The WHO does not recommend use of PPSV in routine childhood immunization programs. The recommendations in the UK are similar, but include people with occupational hazards. Pneumococcal vaccine may be beneficial to control exacerbations of chronic obstructive pulmonary disease (COPD). PPSV is important for those with HIV/AIDS. 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. 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. While the U.S. Centers for Disease Control and Prevention (CDC) recommends immunization in all patients infected with HIV. Adverse events The most common adverse reactions (reported in more than 10% of subjects vaccinated with PPSV 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%). Vaccination schedule Adults and children over two years of age The 23-valent vaccine (for example, Pneumovax 23) is effective against 23 different pneumococcal capsular types (serotypes 1, 2, 3, 4, 5, 6B, 7F,