to the editor: A new series entitled “Putting Prevention into Practice” that started in the April 1, 2000 issue of American Family Physician¹ will help bring evidence-based preventive medicine information to practicing family physicians.

The initial feature presented a succinct case regarding pneumococcal vaccination for adults, and questions and answers to remind or teach us about some of the basic issues. The answers were based on the 1996 recommendations of the U.S. Preventive Services Task Force (USPSTF). The USPSTF is a premier source for well-done and highly respected evidence-based guidelines for preventive services.

Unfortunately, the USPSTF recommendations are not rapidly updated as new evidence becomes available. In a previous AFP article,² it was reported that the American Academy of Family Physicians (AAFP), the American Medical Association and nine other medical societies had issued a joint health alert calling for more extensive use of pneumococcal vaccination. This joint statement called for routine revaccination for immunocompetent persons older than 65 years, who received a first vaccination before the age of 65, and if more than five years has elapsed since the first dose. The answers, based on the USPSTF 1996 recommendations, state that routine revaccination for pneumococcal disease is not recommended.

Which recommendation should the practicing family physician follow? Is the recommendation put forth by 11 medical societies incorrect because they didn't use evidenced-based principles? (Whether or not they did is not stated in the AFP summary.²) Or, are the 1996 USPSTF recommendations incorrect because new information has become available since 1996?

The National Guideline Clearinghouse collects and provides guidelines from multiple sources. These guidelines are often disparate and occasionally the clearing-house provides a synthesis of guidelines that compares and contrasts the guideline recommendations.

A single source (perhaps a group convened by AAFP) that could rapidly respond to disparate recommendations in such guidelines and provide a best current summary and recommendation would be of great value to practicing physicians who may otherwise see only portions of the complete picture, based on which AFP summary they read.

in reply: Definitive data on the benefits of “booster” immunizations are unavailable for pneumococcal vaccine, and the differing recommendations of the U.S. Preventive Services Task Force (USPSTF) and Advisory Committee on Immunization Practices (ACIP) reflect different conclusions in the face of imperfect data. Although it is known that antibody levels decline with time, the limited number of studies of clinical immunity considered by both groups were not consistent in their conclusions.

Findings of one case-control study¹ suggested that immunity declines over time in persons between 55 to 64 years of age (from 88 percent of those immunized within three years to 75 percent of those immunized more than five years after primary immunization). In contrast, a second study² suggested that clinical efficacy persists from seven to 10 years. The USPSTF concluded that this evidence was insufficient to recommend routine revaccination, while noting there may be benefit for high-risk persons more than five years after immunization. At the same time, there are practical considerations that may have been given more weight by ACIP than by the USPSTF:

• Accurately determining immunization status is difficult. Reimmunizing at age 65 will prevent missing those persons who might have mistaken a previous flu shot for a pneumococcal immunization.

• Reimmunizing with the 23-valent vaccine will provide added protection to persons who received an earlier 14-valent vaccine.

• Risks from reimmunization (local reaction) decline with time and should be minimal for those who are revaccinated more than five years after the primary immunization.

Physicians should recognize the clear priority of making sure all persons older than 65 years are immunized at least once. Because only 43 percent of adults older than 65 years received pneumococcal vaccine in 1997, we have a long way to go in reaching the Healthy People goal of immunizing 90 percent of older adults by 2010.³ Additional revaccination as recommended by ACIP may have some additional benefits, although they are likely to be small, and the supporting evidence is weak.