Pneumococcal polysaccharide revaccination: immunoglobulin g seroconversion, persistence, and safety in frail, chronically ill older subjects.

Objectives: To determine the 1-month postpneumococcal polysaccharide-revaccination immunoglobulin G (IgG) antibody response, its persistence at 1 year, and tolerability of revaccination in frail, chronically ill older nursing facility residents.

Design: Prospective study conducted between December 1998 and July 2000.

Setting: Six skilled nursing facilities in the Minneapolis-St. Paul, Minnesota, metropolitan area.

Participants: Sixty-seven subjects aged 65 and older having received primary vaccination with pneumococcal polysaccharide vaccine (PPV) at least 5 years before enrollment.

Intervention: Revaccination with one dose of 23-valent PPV.

Measurements: Adverse events and concentrations of seven individual pneumococcal polysaccharide type-specific IgG antibodies (against serotypes 4, 6B, 9V, 14, 18C, 19F, 23F) and their aggregate before and 1 and 12 months after revaccination.

Results: A significant increase in all individual and aggregate median antibody concentrations over baseline was observed 1 month after revaccination. However, after 1 year, the increase remained significant only for serotypes 6B and 18C and the aggregate parameter. One month after revaccination, the mean increase in antibody concentration over baseline was significantly greater than 1.4-fold for six of the seven serotypes and the aggregate. However, the increase was not significantly greater than 1.4 at 1 year for any of the serotypes or the aggregate. Minor, self-limited localized adverse reactions and systemic reactions occurred in 11.3% of the subjects.

Conclusions: In frail, chronically ill older nursing facility residents, revaccination with 23-valent PPV at least 5 years after primary vaccination (whether primary vaccination occurred before or after age 65) is associated with a significant, albeit brief, immunological response for most of the serotypes tested. Revaccination was well tolerated.