Differences in the immunogenicity of three Haemophilus influenzae type b conjugate vaccines in infants

Response to conjugate Haemophilus influenzae B vaccine among infants in Niamey, Niger.

“…Surveillance for Hib meningitis in Niamey during the period 1981-1996 revealed that only 40 (6.5%) of 611 cases of Hib meningitis among children Ͻ five years of age occurred in infants Ͻ 12 weeks of age; 17 (2.8%) occurred among infants between eight and 12 weeks of age, cases that would potentially be prevented only by the traditional three-dose schedule (assuming two weeks are needed for antibody production following vaccination with the conjugate vaccine). Despite the official EPI vaccination schedule of six, 10, and 14 weeks of age, children in this trial received routine and study vaccines somewhat later (8,13, and 18 weeks of age). One potential risk of delaying the first dose of PRP-T is that children in certain areas may not receive their second DTP injection until much later in infancy.…”

“…Antibody response to Hib vaccines has varied in different studies according to diverse factors, including age at immunization, type of conjugate vaccine, and whether the vaccine is administered in the same syringe as other antigens. [12][13][14][15][16][17][18] Response to certain Hib conjugate vaccines varied in different populations, suggesting that factors such as nutrition, pre-existing antibody to Hib or other antigens, or genetic influences could potentially affect immune response. 19,20 It is therefore reassuring to find that Hib antibody levels among infants in Niamey vaccinated with PRP-T were comparable with those identified in children in industrialized countries as well as those identified in recent studies of PRP-T vaccine in the Gambia, 10,11 since this suggests that efficacy against invasive Hib disease in Niger is likely to be comparable with the high levels observed elsewhere.…”

Priming of Immunological Memory by Pneumococcal Conjugate Vaccine in Children Unresponsive to 23-Valent Polysaccharide Pneumococcal Vaccine

“…However, antibody concentrations are not the only correlate of a protective immunity. As we know from Haemophilus influenzae, conjugate vaccine efficacy is also determined by differences in the kinetics of immune response (17). Demonstration of B-cell memory has largely been based on a rapid and strong antibody response to a dose of plain polysaccharide vaccine after priming with a conjugate vaccine (32,33,54).…”

Naturally Acquired and Conjugate Vaccine-Induced Antibody to Haemophilus influenzae Type b (Hib) Polysaccharide in Malian Children: Serological Assessment of the Hib Immunization Program in Mali

“…[6][7][8][9][10] Accordingly, Hib conjugate vaccines are highly immunogenic, even in young infants. [11][12][13] Introduction of Hib conjugate vaccines into the routine immunization schedule has led to near eradication of invasive Hib disease in many industrialized and transitional countries, and some developing countries. 11,[14][15][16][17] A serum anti-PRP titer 1.0 μg/mL, originally proposed by Kayhty and others 18 is now widely accepted in vaccinology and public health as a titer that is associated with long-term protection against invasive Hib disease.…”