PPV23

PPV23, or the 23-valent pneumococcal polysaccharide vaccine, is a vaccine designed to protect against invasive diseases caused by Streptococcus pneumoniae serotypes 1 through 23. It is used in adults and certain high-risk individuals to reduce the risk of serious pneumococcal infections.

The vaccine is composed of purified capsular polysaccharides from 23 pneumococcal serotypes. It elicits a B-cell–mediated, T-cell–independent immune response rather than a robust memory response. Because of this, PPV23 is less immunogenic in young children and may provide shorter-lasting protection compared with conjugate vaccines. It can reduce the risk of invasive pneumococcal disease caused by the serotypes it covers, but it does not protect against all pneumococcal serotypes, and its effect on non-bacteremic pneumonia is less clear.

Indications for PPV23 focus on adults and certain younger adults at increased risk of pneumococcal disease. It is commonly recommended for adults aged 65 and older and for adults aged 19–64 with conditions such as chronic heart or lung disease, liver disease, diabetes, alcoholism, chronic kidney disease, or immunocompromising conditions; asplenia or functional hyposplenism; and other risk factors. In many guidelines, PPV23 is used in combination with pneumococcal conjugate vaccines, depending on prior vaccination history and local recommendations.

Administration is by intramuscular injection, typically in the deltoid. A second dose may be considered for some high-risk individuals after an interval of several years, but routine revaccination is not recommended for all adults. Common side effects include pain at the injection site, redness, swelling, and mild fever. Serious allergic reactions are rare.