Article in Japanese

Determination of serotype-specific immunity in a child with severe motor and intellectual disability with repeated pneumococcal pneumonia caused by serotypes 6B and 6A after 7-valent pneumococcal conjugate vaccine inoculation

Akiyoshi NARIAI, Takanori YANAI, Yu FUJIWARA, Sayumi SUZUKI

A child with severe motor and intellectual disability was admitted with pneumococcal pneumonia caused by serotypes 6B and 6A, five times and two times, respectively, from the age of 5 years and 3 months to the age of 6 years and 9 months, although she had received the 7-valent pneumococcal conjugate vaccine (PCV7) twice at the age of 4 years and 7 months and 4 years and 9 months and the 23-valent pneumococcal capsular polysaccharide vaccine once at the age of 5 years and 1 month.
The PCV7 and 6A serotype-specific immunity were investigated using serum at the hospitalization for the seventh time. The PCV7 included 6B serotype-specific immunoglobulin (IgG) antibody levels and the 6A serotype-specific IgG antibody concentration was elevated beyond the protective threshold concentration. However, the opsonophagocytic activity (OPA) assay titers against serotypes 6B and 6A were below the protective serotype-specific OPA assay titer threshold. The serotype-specific OPA is considered to be necessary for protection against local pneumococcal infection as well as for protection against invasive pneumococcal desease.
When the patient received one inoculation with a 13-valent pneumococcal conjugate vaccine at a later date, the serotype-specific OPA against serotypes 6B and 6A was elevated above the protection threshold four weeks later.

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Department of Pediatrics, Yokohama Minami Kyousai Hospital

Key words
Received	January 23, 2015
Accepted	April 16, 2015

27 (2)：113─118,2015