Pneumovax

Pneumovax is the brand name for the pneumococcal polysaccharide vaccine PPSV23, manufactured by Merck & Co. It contains purified polysaccharide capsules from 23 serotypes of Streptococcus pneumoniae and is used to prevent infections caused by those serotypes.

The vaccine is a non-conjugate preparation. The polysaccharide antigens stimulate a B-cell–mediated antibody response and do not evoke a strong T-cell–dependent immune response. As a result, PPSV23 can be less immunogenic in young children and may provide shorter-lasting protection in some adults compared with conjugate vaccines. It does not provide protection against serotypes outside the 23 included in the vaccine and may not prevent all pneumococcal diseases.

Indications for Pneumovax include prevention of invasive pneumococcal disease (IPD) and pneumococcal pneumonia caused by the serotypes included in the vaccine. It is commonly recommended for adults aged 65 years and older and for younger adults with certain medical conditions or risk factors, such as chronic heart or lung disease, diabetes, liver disease, alcoholism, smoking, asplenia, or immunocompromising conditions. Vaccination decisions and schedules may vary by country and guideline.

Administration is by a single 0.5 mL dose given intramuscularly (deltoid muscle) or, less commonly, subcutaneously. Some individuals may be candidates for revaccination after a specified interval if they remain at high risk or were vaccinated at a younger age; local guidelines determine exact timing.

Common adverse effects include pain at the injection site, redness, swelling, fever, malaise, and myalgia. Serious allergic reactions are rare. Storage requires refrigeration at 2–8°C; do not freeze.