Immunogenicity and safety after the third vaccination with the 23-valent pneumococcal polysaccharide vaccine in elderly patients with chronic lung disease.

An observational study to assess immunogenicity before and after the first, second, and third vaccinations with the 23-valent pneumococcal polysaccharide vaccine in a cohort of 16 elderly patients with chronic lung diseases was conducted. The safety of this vaccine was also compared between the first, second, and third vaccinations. Serotype-specific immunoglobulin G (IgG) and the opsonization index (OI) for serotypes 6B, 14, 19F, and 23F were analyzed, and adverse local and systemic reactions were compared. The levels of serotype-specific IgG and OI increased significantly 1 month after the first, second, and third vaccinations. Peak IgG levels were higher after the third vaccination than after the second vaccination, but the levels of serotypes 6B, 14, and 19F were not higher than after the first vaccination. Serotype-specific OIs did not differ after the third vaccination compared with the first and second vaccinations. The level of serotype-specific IgG required for killing 50% of bacteria decreased significantly 1 month after the second vaccination. This level was slightly elevated immediately before the third vaccination but decreased after the third vaccination. Although self-limited local and systemic reactions were more frequent after the second and third vaccinations than after the first vaccination, no serious systemic reactions were seen after any vaccination. These data suggest that sustained functional serotype-specific IgG is produced after the first, second, and third vaccinations and they confirm the safety of the second and third vaccinations in elderly people with chronic lung disease.