No randomized or prospective trials regarding the clinical efficacy of revaccination have been completed. However, when reviewing the studies of antibody response, several summary conclusions can be made. Among those who were nonresponders to the initial vaccination, revaccination (even repeated revaccination) is not effective in stimulating any significant antibody response.12-14 Among those who responded to the primary vaccination, revaccination can stimulate a second antibody response—albeit to lower levels and with less duration than after the initial vaccination.13,15-17 Among those who do respond to revaccination, antibody levels can rapidly decline to undetectable levels in a matter of months, and they may or may not retain protection against disease over time.14,15 It appears that revaccination recommendations have been based on the safety of the vaccination, concern for patients at risk and reduced antibody levels, rather than on proven clinical utility.
Recommendations from others
The Advisory Committee on Immunization Practices (ACIP) advises that the vaccine be used in “persons with diseases and other conditions predisposing to the development of bacteremic pneumococcal pneumonia” and that “revaccination should not be done at intervals less than five years.” They state "the value of vaccination on the basis of advanced age is not clear at this time.” (Further details may be found at: www.aafp.org/PreBuilt/agecharts_adultimmunization.pdf.)
The American Academy of Family Physicians, American College of Physicians, the American College of Obstetricians and Gynecologists and the American Diabetes Association follow the ACIP recommendations.