It was reported in a published article that an 11 month old white female with a history of two episodes of otitis media, pharyngitis, and Herpangina who was vaccinated with a third dose of HIB conjugate vaccine. The reporter mentioned that the patient's immunizations, which included three diphtheria toxoid (+) pertussis vaccine (+) tetanus toxoid and three HIB conjugate vaccine were up to date. In October 1996, the patient developed Haemophilus influenzae type B meningitis with an immunodeficiency (also reported as selective antibody deficiency) characterized by low normal serum IgG level, IgA, and IgG-2 subclass levels, and low antibody levels to HIB and tetanus toxoid (also reported as non-detectable antibody titer to Haemophilus influenzae). It was noted that the patient recovered from the haemophilus influenzae type B meningitis with antibiotic therapy without neurological sequelae. An immunologic evaluation revealed low normal serum IgG 379 mg/dl (normal 268-717), low IgA 12 mg/dl (normal 12-31), and low IgG-2 16 mg/dL (normal 30-150). It was mentioned that the patient's antibody titer to Haemophilus influenzae remained non-detectable at < 0.5 micrograms/mL during the infection, after resolution of the infection, and following a fourth immunization. Low values were confirmed by repeat testing. Antibody titers to diphtheria and tetanus toxoid were low after three DTaP immunizations, and anti-B isohemagglutinin was absent (O positive blood). Post immunization pneumococcal antibody titers were protective and not repeated due to adequate levels. The reporter mentioned that several observations had been made by others during a previous evaluation of the efficacy of HIB immunizations that involved vaccine failure with invasive Haemophilus influenzae disease. It was mentioned that IgG Gm immunoglobulin allotyopes were found in Caucasian children which suggested a genetic disposition for a lacunar defect. Additionally there were observations regarding antibody responses in children to unconjugated versus conjugated HIB vaccines which revealed that children who had poor antibody responses to both forms of the vaccine were more likely to have decreased IgG-2 subclass levels and poor antibody responses to other immunizations. The reporter mentioned that the patient fit the pattern with a low IgA and IgG-2 levels and low antibody titers to tetanus toxoids, except that the patient failed to produce a protective HIB antibody response following HIB infection and repeated HIB conjugate vaccine immunizations. According to the reporter this suggested that the patient had a selective antibody deficiency to bacterial polysaccharide antigens associated with IgA-IgG-2 subclass deficiency. Therefore IVIG therapy was initiated in January 1997 and continued until April 1998. After IVIG therapy was discontinued, a re-evaluation at 2.5 years old revealed a normal serum immunoglobin level, normal IgG subclass levels, including IgG-2 135 mg/dL, and normal antibody titers to diphtheria (0.45) and tetanus toxoids (0.96) immunizations, and a normal response to 8 of 12 serotypes of pneumococcal immunization. However, the reporter noted that the patient's antibody titers to HIB remained nonproductive at 0.53 micrograms/mL. Yearly HIB conjugate vaccine immunizations were given and post-vaccination antibody levels were obtained. HIB antibody levels remained nonproductive for another 2.6 years, until finally at 7 years old (approximately 2003) the HIB antibody level was greater than 9.0 micrograms/mL. Thus, from 2.5 to 7 years old only a lacunar defect to Haemophilus influenzae was present. The reporter mentioned that the association of partial IgA and IgG-2 subclass deficiencies with the lacunar antibody deficiency for Haemophilus influenza is not clearly established since the patient's serum immunoglobulin became normal at 2.5 years but the Haemophilus influenzae antibody defect persisted for at least another 2.6 years. The reporter also mentioned that patients who have a selective antibody deficiency usually have recurrent sinopulmonary infections with normal immunoglobin and IgG subclass concentrations but abnormal antibody response to polysaccharide antigens. It was noted that most children with selective antibody deficiency to bacterial pneumococcal polysaccharide antigens outgrow the immune defect. The mechanism for the lacunar and selective antibody deficiency to bacterial polysaccharide antigens immunodeficiency remains unexplained. Lacunar defects involve a missing part of the antigen-recognition molecules required to achieve antibody production. However, the reporter noted that the immune deficiency may resolve spontaneously as demonstrated by the patient. Haemophilus influenzae type B meningitis is considered to be an other important medical event (OMIC). Additional information has been requested.