Early responses to nonconjugated polyribosylribitol phosphate challenge as evidence of immune memory after combined diphtheria-tetanus-pertussis-polio-Haemophilus influenzae type b primary vaccination

Abstract

The results demonstrate the development of anti-PRP immune memory at an early age, 4 and 6 months after completion of a three dose primary vaccination course of combined DTPa-IPV/Hib vaccine. The ability of primed infants to mount a rapid response is an important observation given the high risk of Hib infection at this critical age.

Assessing Efficacy ofHaemophilus influenzaeType b Combination Vaccines

“…Indeed, several epidemiologic studies confirmed that having an older sibling in the household [82,83] was a significant risk factor for acquiring invasive Hib disease [84]. Although Hib combination vaccines are associated with diminished anti-PRP antibody responses after the 3-dose primary immunization series given in the first 6 months of life, a fourth (booster) injection given in the second year of life is highly immunogenic, achieving anti-PRP antibody concentrations 120-30 mg/mL [7,8,85]. Thus, virtually all children receiving a fourth injection will be protected from disease, and we also can expect that the magnitude of booster response will be sufficient to decrease Hib colonization in the older age groups that historically were responsible for transmission of the organism.…”

Immunogenicity of a Haemophilus influenzae type b–tetanus conjugate vaccine when administered separately or in combined vaccines for primary immunization in two consecutive national schedules in Turkey

“…16 Some studies have demonstrated the development of anti-PRP immune memory at an early age, after completion of a three-dose primary vaccination course of combined DTaP-IPV/Hib vaccine. 10,17 Many investigators believe that immune memory is most important, and even if the combined vaccines for primary immunization caused a decrease in anti-Hib antibody response after primary immunization, higher antibody responses to booster doses in children vaccinated with combined vaccine can be considered to be protective for invasive Hib disease. Nevertheless the duration of protection is not known accurately and continued surveillance of invasive Hib infections among children who have been vaccinated with different schedules can guide new vaccination strategies.…”

Primary and booster immunization with a diphtheria, tetanus, acellular pertussis, hepatitis B (DTPa–HBV) and Haemophilus influenzae type b (Hib) vaccine administered separately or together is safe and immunogenic

“…16 Plain PRP used in this study and in others as an immunological challenge, is used to mimic exposure to wildtype Hib infection as a method of assessing immunological memory. 17,18 Data have also shown that when corrected for total antibody level, anti-PRP antibody avidity does not differ with different methods of administration including administration of Hib separately or in combination. 14 The aim of this study was to investigate the immunogenicity and reactogenicity of a candidate Hib vaccine and quadrivalent DTPa-HBV vaccine given either as a single mixed injection or administered simultaneously in opposite limbs for primary vaccination to healthy infants at 2, 4, and 6 months of age.…”