Long-term effect of pneumococcal polysaccharide vaccination on serum IgM and IgG antibody levels in individuals splenectomized for trauma.

The IgM and IgG pneumococcal antibody levels were measured one year after vaccination with a 14-valent pneumococcal polysaccharide vaccine in 12 individuals splenectomized due to trauma and 10 non-splenectomized individuals. The results were compared with the antibody levels before and four weeks after vaccination. One year after vaccination there were only minor differences between the two groups. The IgM response to most of the serotypes had almost vanished. There were only significant IgG responses to a few serotypes after one year, but the mean antibody levels of all the 14 serotypes showed some persistence of the IgG response. There was a tendency for the splenectomized individuals that were younger than 15 years of age to have a somewhat reduced antibody response after pneumococcal vaccination. This could indicate that pneumococcal vaccination might be less efficient in that group of individuals where the need for a protective vaccine is most urgent.