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Children do not respond equally to vaccines, nor do adults. Eight years ago, my group introduced the concept of low vaccine responder‒ and normal vaccine responder children. We tested 499 infants for antibody levels to multiple routine vaccines given in a 2-4-6 month series. Surprisingly, we found that 11 percent were what we termed “low responders” because the children developed subprotective antibody levels to at least four of six vaccine antigens (ingredients in diphtheria, tetanus, pertussis, and Haemophilus influenzae type b vaccines). We tested to seven other vaccines (polio serotypes 1, 2, 3, hepatitis B, and three pneumococcal conjugate vaccine components) and 50 percent developed subprotective antibody levels, which we termed “low responders.” 

When we studied the immunity of the low responder infants, we found that they had problems with all three types of immunity cells: B cells that make antibody, T cells that help B cells and kill viruses, and antigen-presenting cells (APCs) that take the vaccine ingredients to the lymph nodes and spleen, where the immune processing occurs. Taken together, the immunity profile of the infants suggested delayed immunologic maturation compared with normal vaccine responders, and we introduced the term “prolonged neonatal-like immune profile.” Since we had identified the immune problem in 11 percent of all the infants we studied, we realized that we had discovered the most common immune problem ever described, with the closest second being selective IgA deficiency, occurring in 1 in 600 children.

My group recently published another paper on the topic of variation in vaccine responsiveness in children. The specific focus of our newest paper was on examining how children’s vaccine response changes over time, from the primary vaccine responses in year 1 of life through the booster vaccinations in year 2. We sought to define four vaccine response groups based on antibody levels rather than two groups, to allow better resolution of the broad range of antibody measurements. Head over to Medscape to read the full story.