Antibody persistence and immunologic memory in children vaccinated with 4 doses of pneumococcal conjugate vaccines: Results from 2 long-term follow-up studies

Abstract

To investigate long-term antibody persistence following the administration of the 10-valent pneumococcal non-typeable Haemophilus influenzae protein D conjugate vaccine (PHiD-CV), we present results of 2 follow-up studies assessing antibody persistence following 2 3+1 schedules up to 4 (NCT00624819 – Study A) and 5 years (NCT00891176 – Study B) post-booster vaccination. In Study A, antibody persistence was measured one, 2 and 4 years post-booster in children previously primed and boosted with PHiD-CV, or primed with the 7-valent pneumococcal conjugate vaccine (7vCRM) and boosted with either PHiD-CV or 7vCRM. In Study B, PHiD-CV was co-administered with meningococcal vaccines, and pneumococcal antibody persistence was measured 2, 3 and 5 years post-booster. An age-matched control group, unvaccinated against Streptococcus pneumoniae, was enrolled in Study A, allowing assessment of immunologic memory by administration of one dose of PHiD-CV to both primed (4 years post-booster) and unprimed 6-year-old children. Four years post-booster (Study A), antibody concentrations and opsonophagocytic activity (OPA) titers remained higher compared to the pre-booster timepoint, with no major differences between the 3 primed groups. Antibody persistence was also observed in Study B, with minimal differences between groups. The additional PHiD-CV dose administered 4 years post-booster in Study A elicited more robust immune responses in primed children than in unprimed children. Long-term serotype-specific antibody persistence and robust immunologic memory responses observed in these 2 studies suggest induction of long-term protection against pneumococcal disease after PHiD-CV vaccination.

Letter to the editor to: Isturiz et al. Streptococcus pneumoniae serotype 19A: worldwide epidemiology. Expert review of vaccines 2017;16(10):1007-27

“…The clinical significance of the amount of IgG or the number of circulating B cells soon after vaccination is completely unknown [28], and there is currently no known link to VE. The results of two long-term follow-up studies evaluating long-term antibody persistence up to 5 years post-PHiD -CV booster have been recently published [29]. In one study, antibodies were measured 1, 2, and 4 years post booster in children previously primed and boosted with PHiD-CV, or primed with PCV7 and boosted with either PHiD-CV or PCV7 [29].…”

“…The results of two long-term follow-up studies evaluating long-term antibody persistence up to 5 years post-PHiD -CV booster have been recently published [29]. In one study, antibodies were measured 1, 2, and 4 years post booster in children previously primed and boosted with PHiD-CV, or primed with PCV7 and boosted with either PHiD-CV or PCV7 [29]. Anamnestic responses were also evaluated in children given an additional dose of PHiD-CV 4 years after the initial booster [29].…”

“…In one study, antibodies were measured 1, 2, and 4 years post booster in children previously primed and boosted with PHiD-CV, or primed with PCV7 and boosted with either PHiD-CV or PCV7 [29]. Anamnestic responses were also evaluated in children given an additional dose of PHiD-CV 4 years after the initial booster [29]. In the second study, antibody persistence was measured 2, 3, and 5 years post booster [29].…”

“…Anamnestic responses were also evaluated in children given an additional dose of PHiD-CV 4 years after the initial booster [29]. In the second study, antibody persistence was measured 2, 3, and 5 years post booster [29]. Long-term serotype-specific antibody persistence and robust immunological memory responses observed in these two studies suggested induction of long-term protection against pneumococcal disease after PHiD-CV vaccination [29].…”

“…In summary, there is similar evidence of direct protection against serotype 19A for both vaccines in children [2,12], although herd effects in older ages appear more variable. There is evidence of reduction of serotype 19A carriage from a randomized controlled trial [32] and evidence of long-term protection and anamnestic responses for PHiD-CV [29]. Surveillance data from various countries is variable and very difficult to compare due to inherent challenges in attempting to reconcile differences in surveillance systems, epidemiology, public health policies, and intervention strategies.…”