Modeling pneumococcal nasopharyngeal acquisition as a function of anticapsular serum antibody concentrations after pneumococcal conjugate vaccine administration

A toddler PCV booster dose following 3 infancy priming doses increases circulating serotype-specific IGG levels but does not increase protection against carriage

“…The following can be a plausible explanation. Correlation between serotype-specific IgG concentrations and nasopharyngeal acquisition of pneumococcus post infant 3-dose primary series was clearly demonstrated [33,34]. It may be speculated that high blood IgG concentration is not, by itself, sufficient for the prevention of carriage acquisition.…”

“…Nevertheless, all serology results were adjusted for ethnic group. Furthermore, in another study, ethnicity did not 30 24 23 22 21 20 19 18 17 16 15 14 13 12 11 10 9 8 7 6 5 4 3 2 a2,b2,c2 a2,b1,c2 a2,b2,c2 a2,b2,c2 influence the association between IgG concentrations and prevention of carriage despite differences in carriage rates [34]. New pneumococcal acquisition was defined as acquisition of a serotype not seen at any previous visit.…”

Pneumococcal whole-cell and protein-based vaccines: changing the paradigm

“…[35] and higher serum anticapsular polysaccharide antibodies are needed to prevent NP acquisition versus prevention of IPD after PCV vaccination. [36] Transudation of antibodies from serum into the nasal mucosa is minimal in times of health but increases during viral URI-induced NP inflammation.The best physiological and immunological state to assess correlation of vaccine-induced anti-pneumococcal antibody levels and protection of pneumococcal colonization by WCVs and PPVs is during a viral URI- the clinical setting for development of pneumococcal infection. [18,37]…”

“…[35] and higher serum anticapsular polysaccharide antibodies are needed to prevent NP acquisition versus prevention of IPD after PCV vaccination. [36] Transudation of antibodies from serum into the nasal mucosa is minimal in times of health but increases during viral URI-induced NP inflammation.…”

Geographical variability in anticapsular IgG levels elicited by pneumococcal conjugate vaccines: Implications for clinical protection?

“…Multiple attempts, tireless but ultimately unconvincing, have been made to derive precise correlates of protection against asymptomatic colonization. In fact, studies come to very different conclusions as to whether there is any correlation between higher IgG levels and a lower rate of nasopharyngeal acquisition, even for the same serotypes (Ojal et al, 2018;Dagan et al, 2016).…”