Concentration and High Avidity of Pneumococcal Antibodies Persist at Least 4 Years after Immunization with Pneumococcal Conjugate Vaccine in Infancy

Abstract

To provide more extensive evidence of long-term effects of vaccination on immunity against Streptococcus pneumoniae, a follow-up study of the Finnish Otitis Media (FinOM) Vaccine Trial was conducted. One of the objectives was to assess the persistence and avidity of pneumococcal antibodies 4 years after pneumococcal vaccination given in infancy. Children with complete follow-up in the FinOM trial up to 24 months of age were invited to a single visit in their fifth year of life. A blood sample was taken from all children for determination of anticapsular antibody concentrations to vaccine serotypes and avidity of antibodies to three serotypes. Children had been vaccinated at 2, 4, 6, and 12 months of age with 7-valent pneumococcal capsular polysaccharide, CRM197 conjugate vaccine (PCV7), or a control vaccine. Serum IgG antibody concentrations to vaccine serotypes remained significantly higher in children who had received PCV7 than in control children for 4 years after the fourth PCV7 dose. Concentrations of antibodies to frequently carried serotypes (6B and 19F) declined less than those of antibodies to a rarely carried serotype (4), suggesting that natural boosting contributed to antibody persistence. Furthermore, antibody avidity was significantly higher in PCV7 than control vaccine recipients. Four doses of PCV7 given in infancy elicit long-lasting antibody responses with high avidity. (This study has been registered at ClinicalTrials.gov under registration no. NCT00378417.)

Long‐term immune responses and comparative effectiveness of one or two doses of 7‐valent pneumococcal conjugate vaccine (PCV7) in HIV‐positive adults in the era of combination antiretroviral therapy

“…Our data show that the antibody concentrations post-vaccination remained significantly elevated from baseline and declined very gradually in the subsequent five years, similar to the long-lasting (5- to 10-year) responses elicited against most but not all of the serotypes in children and adolescents post-PCV series in infancy [34–36]. Slow decay of anti-pneumococcal-specific IgG post-PCV in contrast to the more rapid decay post-PPV suggests that the generation of memory B cells via a T-cell-dependent response and natural boosting contributed to antibody persistence [35,37–39].…”

Streptococcus pneumoniae Serotype 1 Burden in the African Meningitis Belt: Exploration of Functionality in Specific Antibodies

“…Interestingly, the avidity of antibodies did not show any difference between immunized and unimmunized subjects. A higher avidity of antibodies has been postulated to contribute to enhanced functionality and to represent a surrogate marker of successful priming of immunological memory after vaccination against H. influenzae and N. meningitidis (35,36). However, the literature on the relationship between anti-pneumococcal IgG avidity and OPA is currently conflicting; therefore, the impact of this parameter remains debated (36)(37)(38).…”

The Efficacy and Duration of Protection of Pneumococcal Conjugate Vaccines Against Nasopharyngeal Carriage

“…The polysaccharide capsule of 19F is more resistant to complement deposition than 6B and requires higher levels of antibodies for opsonophagocytosis. 38 However, although trials 37,40,41 have shown persistence of serum antibodies several years after vaccination, the exact mechanism underlying the protection against acquisition of carriage remains unclear. Such mechanisms could perhaps involve mucosal immunological responses 42 in addition to preexisting circulating serum immunoglobulin (IgG), with serological markers incompletely capturing the mucosal response.…”