Evidence of maternal transfer of antigen-specific antibodies in serum and breast milk to infants at high-risk of S. pneumoniae and H. influenzae disease

Prevalence of nasopharyngeal Streptococcus Pneumoniae carriage in infants: A systematic review and meta-analysis of cohort studies and randomized controlled trials

This study aims to examine the prevalence of nasopharyngeal Streptococcus pneumoniae carriage (NSPC) in infants during their first two years of life and to compare the carriage rates among different vaccine groups and country income-levels. This will be achieved through a systematic review of the published literature, specifically focusing on data from cohort studies and randomized controlled trials. A comprehensive search was conducted in four electronic databases: PubMed, Web of Science, ScienceDirect, and Scopus, using a predefined search strategy. Forty-nine articles met the inclusion criteria for this systematic review. According to the results obtained from the random effects model, the pooled mean prevalence of NSPC was 1.68% at birth (95% CI [0.50; 5.47]), 24.38% at 1 to 4 months (95% CI [19.06; 30.62]), 48.38% at 4 to 6 months (95% CI [41.68; 55.13]), 59.14% at 7 to 9 months (95% CI [50.88; 66.91]), 48.41% at 10 to 12 months (95% CI [41.54; 55.35]), 42.00% at 13 to 18 months (95% CI [37.01; 47.16]), and 48.34% at 19 to 24 months (95% CI [38.50; 58.31]). The highest NSPC rates were observed among children aged 4 to 6 months and 7 to 9 months across all vaccine groups. Low-income countries consistently demonstrated the highest NSPC rates across all age categories studied. This systematic review and meta-analysis provide robust evidence of the high prevalence of NSPC in infants aged 4 to 6 months and 7 to 9 months in all vaccine groups, with persistent regional disparities, especially among low-income countries. The study highlights the need for continuous monitoring of NSPC trends, particularly the emergence of non-vaccine serotypes. Policymakers and healthcare providers should leverage these findings to enhance vaccination strategies, aiming to minimize the overall burden of pneumococcal diseases in infants.

Incidence of pneumococcal disease in children in Germany, 2014-2019: a retrospective cohort study

BACKGROUND

Novel, expanded valency pneumococcal conjugate vaccines (PCVs) are in development to reduce the burden of pneumococcal disease (PD) in children. To understand the potential value of new vaccines in Germany, this study estimated the residual burden of PD in children < 16 years old from 2014 to 2019, using administrative health data from a large German claims database.

METHODS

Outpatient and inpatient cases of all-cause pneumonia (ACP), pneumococcal pneumonia (PP) and invasive pneumococcal disease (IPD) were identified in the InGef database. Incidence rates (IRs) with 95% confidence intervals (CI) were calculated as number of episodes/person-years (PY) at risk. The Mann-Kendall test assessed time trends in incidence.

RESULTS

There were no significant trends in IRs of IPD or PP from 2014 to 2019. For ACP, IRs declined from 2014 to 2019; 2,213 (CI 2,176-2,250) to 1,503 (CI 1,472-1,534) per 100,000 PY (p = 0.017). IRs of ACP and PP were highest among children aged 12-23 months; 4,672 (CI 4,584-4,762) and 20.8 (CI 15.3-27.5) per 100,000 PY, respectively. For IPD, children 5-11 months-old had the highest IRs, at 14.7 (CI 9.0-22.7) per 100,000 PY.

CONCLUSIONS

From 2014 to 2019 there were no discernible trends in the IRs of PP or IPD, but the IRs of ACP declined in children aged < 16 years. The highest IRs of ACP, PP and IPD were observed in children < 2 years of age, highlighting the importance of infant pneumococcal vaccination in the prevention of pediatric PD. The clinical burden of pediatric PD in Germany persists. Continued surveillance of changing pneumococcal burden, serotype distribution, antimicrobial resistance and vaccination status is critical to better understand the factors driving incidence of PD and to inform future vaccination strategies.

Maternal Immunization with Adjuvanted Recombinant Receptor-Binding Domain Protein Provides Immune Protection against SARS-CoV-2 in Infant Monkeys

Maternal vaccinations administered prior to conception or during pregnancy enhance the immune protection of newborn infants against many pathogens. A feasibility experiment was conducted to determine if monkeys can be used to model the placental transfer of maternal antibody against SARS-CoV-2. Six adult rhesus monkeys were immunized with adjuvanted recombinant-protein antigens comprised of receptor-binding domain human IgG1-Fc fusion proteins (RBD-Fc) containing protein sequences from the ancestral-Wuhan or Gamma variants. The female monkeys mounted robust and sustained anti-SARS-CoV-2 antibody responses. Blood samples collected from their infants after delivery verified prenatal transfer of high levels of spike-specific IgG, which were positively correlated with maternal IgG titers at term. In addition, an in vitro test of ACE2 neutralization indicated that the infants' IgG demonstrated antigen specificity, reflecting prior maternal immunization with either Wuhan or Gamma-variant antigens. All sera showed stronger ACE2-RBD binding inhibition when variants in the assay more closely resembled the vaccine RBD sequence than with more distantly related variants (i.e., Delta and Omicron). Monkeys are a valuable animal model for evaluating new vaccines that can promote maternal and infant health. Further, the findings highlight the enduring nature and safety of the immune protection elicited by an adjuvanted recombinant RBD-Fc vaccine.

Protective Characteristics of Human Breast Milk on Early Childhood Otitis Media: A Narrative Review

Introduction: Human breast milk (HBM) contains a complex and dynamically changing variety of factors that contribute to the infant's developing immune system's ability to fight upper respiratory tract infections, including otitis media (OM). We sought to summarize the current evidence on the protective characteristics of HBM, through direct or donated feeding, toward early childhood OM. Methods: For this narrative review, we performed a literature search on OM in the context of HBM feeding in the PubMed, Embase, and Google Scholar databases, between January 1, 2008, and July 1, 2023. Results: Immunoglobulin A (IgA) provides a short-term immunity of 2-3 days against otopathogens causing OM. IgA-mediated immunity is effective against OM up to 7 months of age if breastfeeding continues. The role of transferred IgM and IgG in HBM is unclear. Although there is a potential protective value of microRNA, hormones, oligosaccharides, stem cells, and interleukins present in HBM, their role is unclear. Any duration of breastfeeding is superior to no breastfeeding in OM risk reduction, with a big variability among studies (odds ratio 0.23-0.81, depending on the duration). Duration of breastfeeding ≥6 months was found to be the most effective in OM risk reduction, but there was no evidence of continued benefits after 2 years of age. Expressed breastfeeding was not shown to be more beneficial. The protective values of donor HBM against OM are still undetermined. Conclusion: HBM has numerous components that contribute to protection against early childhood OM.