Antibody activity before and after pneumococcal vaccination of otitis-prone and non-otitis-prone children.

The antibody activity of the IgM class and subclasses of IgG and IgA against pneumococcal bacteria of types 3, 6A and 19F was studied before and after administration of a pneumococcal vaccine (Pneumovax) in a group of children with recurrent acute otitis media (rAOM) and in groups of non-otitis-prone children. Only occasionally was there a significant rise in antibody activity after vaccination in any of the groups. There was no difference in the response to vaccination between rAOM children and healthy children. However, rAOM children exhibited lower antibody activities in most Ig subclasses against pneumococcus type 6A--a common causative agent in AOM--before as well as after vaccination compared with the healthy children. The results indicate that the response to vaccination is equally poor in all children, irrespective of whether they have a history of frequent attacks of acute otitis media, but, in contrast to healthy children, the rAOM children seem to have an inability to mobilize antibodies in response to infections with some pneumococcal types.