Pneumococcal IgG Antibody Responses to 23vPPV in Healthy Controls Using an Automated ELISA

Baseline Pneumococcal IgG Levels and Response to 23-Valent Pneumococcal Polysaccharide Vaccine among Adults from Beijing, China

PURPOSE

To investigate the baseline levels of serotype-specific IgG antibodies to Streptococcus pneumoniae (S. pneumoniae) and assess their impact on the assessment of vaccine immunogenicity.

METHODS

We used a subset of serum samples from a randomized controlled trial. The blood of 584 healthy participants was collected on day 0 before and day 28 after the 23-valent pneumococcal polysaccharide vaccine (PPSV23) vaccination. Serotype-specific IgG against PPSV23-covered serotypes were measured by the World Health Organization (WHO) reference enzyme-linked immunosorbent assay (ELISA). Vaccine immunogenicity was compared using conversion rates (proportion of participants with IgG levels following immunization that are 2-fold greater than the baseline) and geometric mean fold rises (GMFRs) between the two groups, which were grouped according to pre-vaccination (baseline) IgG antibody levels.

RESULTS

Our data showed that over half of individuals have baseline IgG levels for 15 out of 23 serotypes above 1.3 µg/mL, and geometric mean concentrations (GMCs) were generally higher in the elderly group and the female group; significant differences were found in 15 serotypes for vaccine immunogenicity based on the seroconversion rate or GMFRs between individuals with baseline IgG ≥ 1.3 µg/mL and individuals with baseline IgG < 1.3 µg/mL. The seroconversion rate decreased with the increase of baseline IgG levels according to a linear regression model.

CONCLUSIONS

The assessment of vaccine immunogenicity could be impacted by the fact that many adults had high baseline antibody levels. This study is registered in the Chinese Clinical Trial Registry, number NCT05298800.

Navigating diagnostic options for inborn errors of immunity in children: a case-based illustration

PURPOSE OF REVIEW

In recent years, there has been a dramatic increase in the number of recognized inborn errors of immunity (IEI), many of which present in childhood. This review discusses diagnostic approaches for some of the more common presentations of IEI in childhood.

RECENT FINDINGS

Implementation of newborn screening (NBS) using the T cell receptor excision circle (TREC) assay has led to the timely identification of patients with severe combined immunodeficiency (SCID) as well as both syndromic and nonsyndromic forms of T cell lymphopenia, including DiGeorge syndrome. Improvements in the availability of immunophenotyping assays, genetic testing and advanced diagnostic techniques such as the artificial thymic organoid system can improve diagnostic clarity and impact management plans. Diagnostic improvements in humoral immunodeficiency include development of novel assays to quantify and functionally evaluate polysaccharide vaccine response.

SUMMARY

IEI represent a rapidly growing field, particularly in paediatrics. Use of state-of-the-art diagnostic testing can facilitate rapid identification of IEI, hopefully allowing for initiation of prompt treatment and improved patient outcomes.