Streptococcus pneumoniae (pneumococcus) is an important pathogen that causes
pneumonia,
bacteremia, and
meningitis in adults. In recent years, pneumococcal isolates resistant to
penicillin have become increasingly prevalent in the U.S. For these reasons, wide use of the
pneumococcal vaccine has been advocated.
Pneumococcal vaccines have been proven to be effective in preventing the invasive complications of S pneumoniae
infection. The efficacy of
pneumococcal vaccines in preventing non-bacteremic
pneumonia in high-risk subjects, however, has not been proven. The current
pneumococcal vaccine is limited because it includes the
antigens of the serotypes known to be associated with invasive
infection, and it elicits a thymus-independent, B-cell response that evokes no memory and a poor immunologic response in many of the patients at greatest risk for
pneumococcal infection. In the absence of data concerning efficacy of the
pneumococcal vaccine against
pneumonia, it is difficult to argue that it is cost-effective for this purpose. I concur with the recommendations for use of
pneumococcal vaccine to prevent
bacteremia, but I am skeptical about the
vaccine's efficacy against
pneumonia. More data and an improved
vaccine are necessary.