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KMID : 1134220080280030052
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Hanyang Medical Reviews
2008 Volume.28 No. 3 p.52 ~ p.57
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Pneumococcal Vaccine
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Kim Sung-Han
Woo Jun-Hee
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Abstract
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Streptococcus pneumoniae causes considerable morbidity and mortality. There are currently two types of pneumococcal vaccine available under license: pneumococcal polysaccharide vaccines(PPV23) and pneumococcal conjugate vaccines(PCV-7). PPV23 contains T-cell independent antigens which stimulate mature B lymphocytes and produce an effective antibody response. However T-lymphocytes are not involved which leads to an absence of immunological memory and lack of an anamnestic response on challenge. The 23-valent vaccine is reported to be effective in older children and adults, and is currently recommended for high-risk patients such as hyposplenic patients and the general elderly population. PPV23 appears cost effective for elderly patients PCV-7 has high efficacy against radiological pneumonia and invasive pneumococcal disease, acute otitis media, reduces the nasopharyngeal colonization rate of vaccine strain, and provides herd immunity. PCV-7 may also provide an effective new tool to reduce disease caused by drug-resistant strains of pneumococci. But this vaccine has limited serotype coverage, replacement phenomena. It remains unknown if long-term serotype shifts would be caused by PCV-7. And the possibility of the spread and acquisition of virulent non-vaccine serotypes is a real threat which must be monitored. New PCVs including more serotypes could prove to be good options in the future for all age groups. Several protein-based pneumococcal vaccine candidates (currently under investigation in animal models) offer the potential advantage of serotype independent protection in the near future.
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KEYWORD
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pneumococcal vaccine, polysaccharide vaccine, protein conjugate vaccine
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