Anti-Polyribosylribitol Phosphate Antibody Concentrations and Avidities in Children since the Start ofHaemophilus influenzaeType b Immunization of Infants in the United Kingdom

Abstract

The introduction of routine infant immunization with Haemophilus influenzae type b (Hib) conjugate vaccines in the United Kingdom in 1992 led to a significant reduction in invasive disease due to this organism. Subsequently, between 1999 and 2003 there was an increase in the number of immunized children with Hib infection. We investigated whether the rise in cases was related to changes in anti-polyribosylribitol phosphate (PRP) antibody concentration or avidity. Using stored sera, we analyzed temporal changes in antibody levels among 3-to 5-year-old children immunized between 1991 and 2000. Anti-PRP antibody concentrations were higher in 3-to 5-year-olds who received infant immunization in 1991 than those in subsequent years. This difference may be related to changes in either the mode of administration of Hib conjugate vaccines or the rates of Hib nasopharyngeal carriage. This study emphasizes the factors affecting anti-PRP antibody concentration following immunization with conjugate vaccines and the importance of these in long-term protection from invasive disease.

Challenges in Estimating the Impact of Pneumococcal Conjugate Vaccines Through Surveillance

“…20,21 Studies undertaken in children in Kathmandu have demonstrated an Hib carriage prevalence of between 4.1 and 8.9% depending on the age group and population studied. 16,22 This is similar to the prevalence seen in other areas of the world where Hib is known to be a significant cause of meningitis and pneumonia.…”

“…The United Kingdom incorporated routine infant HibCV (at 2, 3 and 4 months) in 1992, which lead to a dramatic decline in the annual incidence of invasive Hib disease (from 28.3/100,000 in the preimmunization era to 0.97/100,000 by 1998 in children under 5 years of age). 16 However, this was followed by a year-byyear increase in the incidence of invasive Hib (from 1999 to 2003). The cause was likely to have been multifaceted, occurring at a time when there was no booster inclusion and acellular pertussis combination vaccines with group C meningococcal vaccine being newly introduced, potentially leading to interference with Hib responses.…”

“…14,15 The loss of protection more than 1 year after primary infant immunization is associated with a fall in the anti-polyribosylribitol phosphate (PRP) antibody, with loss of population protection emerging almost a decade after vaccine implementation. 16,17 An HibCV booster is not currently part of the Expanded Program on Immunization (EPI) schedule, and data on the persistence of antibody in a developing country setting is lacking. Cases of Hib disease re-emerged in The Gambia, 8 years after the introduction of the HibCV into the primary vaccination program in 1997 and emphasized the possibility that sustaining immunity may be an important issue in resource-poor settings just as it was in the United Kingdom.…”

Study of Serologic Response Rate to Haemophilus influenzae Type B After Administration of the Third Dose of Pentavalent Vaccine in Children Aged 12 Months in Karaj City in 2016

“…Protective antibody concentrations (short-term and long-term protective thresholds) were > 0.15 µg/mL and > 1.0 µg/mL, respectively. Anti-PRP antibody concentrations in serum were determined by using a standard protocol (10,11).…”

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

“…4,5 Hib polysaccharide-protein conjugate vaccines developed in the 1980s stimulate a T cell-dependent immune response, which leads to immunologic memory, and an immunoglobulin class switch with resultant increased antibody affinity and avidity. [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.…”