The Protective Role of Maternal Immunization in Early Life

Antenatal tetanus, diphtheria, and acellular pertussis (Tdap) immunization and risk of serogroup 19 IPD in children: An indirect cohort study

The tetanus-diphtheria-acellular pertussis (Tdap) vaccine has been indicated for pregnant women in Quebec, Canada since 2018. Recent literature suggests maternal Tdap interferes with the pneumococcal vaccine response in children exposed in utero because of maternally transferred anti-diphtheria antibodies, a phenomenon known as blunting. Using an indirect cohort study, we investigated whether maternal Tdap vaccination could alter the protection of PCV vaccines against serotype 19A/F IPD (conjugated to diphtheria toxoid in PCV10). Thirty-seven immunized IPD cases (serotype 19A/F) and 90 immunized IPD controls (non-vaccine serotypes) were analyzed using multivariate logistic regression. Our analyses did not identify antenatal Tdap exposure as a risk factor for IPD in vaccinated children, with and odds ratio close to the null (odds ratio = 0.82, 95%CI = 0.32-2.07). As this study is the first to assess the impact of maternal immunization on pneumococcal disease risk, future investigations involving a larger number of cases should be conducted to confirm or infirm our findings.

Preschool-age children maintain a distinct memory CD4+ T cell and memory B cell response after SARS-CoV-2 infection

The development of the human immune system lasts for several years after birth. The impact of this maturation phase on the quality of adaptive immunity and the acquisition of immunological memory after infection at a young age remains incompletely defined. Here, using an antigen-reactive T cell (ARTE) assay and multidimensional flow cytometry, we profiled circulating severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-reactive CD3+CD4+CD154+ T cells in children and adults before infection, during infection, and 11 months after infection, stratifying children into separate age groups and adults according to disease severity. During SARS-CoV-2 infection, children younger than 5 years old displayed a lower antiviral CD4+ T cell response, whereas children older than 5 years and adults with mild disease had, quantitatively and phenotypically, comparable virus-reactive CD4+ T cell responses. Adults with severe disease mounted a response characterized by higher frequencies of virus-reactive proinflammatory and cytotoxic T cells. After SARS-CoV-2 infection, preschool-age children not only maintained neutralizing SARS-CoV-2-reactive antibodies postinfection comparable to adults but also had phenotypically distinct memory T cells displaying high inflammatory features and properties associated with migration toward inflamed sites. Moreover, preschool-age children had markedly fewer circulating virus-reactive memory B cells compared with the other cohorts. Collectively, our results reveal unique facets of antiviral immunity in humans at a young age and indicate that the maturation of adaptive responses against SARS-CoV-2 toward an adult-like profile occurs in a progressive manner.

Maternal influences on offspring food allergy

The prevalence of allergies has been globally escalating. While allergies could appear at any age, they often develop in early life. However, the significant knowledge gap in the field is the mechanisms by which allergies affect certain people but not others. Investigating early factors and events in neonatal life that have a lasting impact on determining the susceptibilities of children to develop allergies is a significant area of the investigation as it promotes the understanding of neonatal immune system that mediates tolerance versus allergies. This review focuses on the research over the recent 10 years regarding the potential maternal factors that influence offspring allergies with a view to food allergy, a potentially life-threatening cause of anaphylaxis. The role of breast milk, maternal diet, maternal antibodies, and microbiota that have been suggested as key maternal factors regulating offspring allergies are discussed here. We also suggest future research area to expand our knowledge of maternal-offspring interactions on the pathogenesis of food allergy.

A review of neonatal lupus syndrome

This review article discusses neonatal lupus syndrome (NLS), an immune-mediated disease caused by maternal antibodies. Maternal antibodies in the fetal circulation are mostly but not always protective. NLS is a disease caused by pathogenic maternal autoantibodies in the fetal circulation. The passive immunization of the fetus by NLS-causing maternal antibodies may occur in the absence of a previously known maternal systemic autoimmune rheumatic disease (SARD). Screening for NLS-related antibodies in patients with related SARD or those in whom there is a risk of NLS including first-degree relatives should occur before pregnancy. This screening is best performed as part of a collaborative relationship between obstetrics and rheumatology. Pregnancy preparations in those with SARD include transitioning to pregnancy-safe medications. The symptoms of NLS range from minor skin rashes to fetal demise from heart block. Fetal screening allows for maternal therapeutic interventions that may be beneficial, as well as the use of fetal pacemakers in the more severe cases that include cardiac NLS.

COVID-Vaccines in Pregnancy: Maternal and Neonatal Response over the First 9 Months after Delivery

Vaccination against SARS-CoV-2 has been demonstrated to be safe during gestation. Nevertheless, there are no robust data investigating the entity of maternal antibodies' transmission through the placenta to the newborn and the persistence of the antibodies in babies' serum. The objective of this study is to assess the maternal antibody transmission and kinetics among newborns in the first months of life. Women having received one or two doses of anti-SARS-CoV-2 mRNA-vaccines during pregnancy at any gestational age, and their newborns, were recruited and followed-up over 9 months. Ninety-eight women and 103 babies were included. At birth, we observed a significant positive correlation between maternal and neonatal serum anti-SARS-CoV-2 antibody levels and a significant negative correlation between the time since last dose and antibody levels in mothers with two doses. Over the follow-up, the birth antibody level significantly decreased in time according to the received doses number at 3, 6, and 9 months. During the follow-up, we registered 34 dyad SARS-CoV-2 infection cases. The decreasing trend was slower in the SARS-CoV-2 infection group and among breastfed non-infected babies. Antibodies from maternal anti-SARS-CoV-2 vaccination are efficiently transferred via the placenta and potentially even through breast milk. Among newborns, antibodies show relevant durability in the first months of life.

An Overview of Antibiotic Therapy for Early- and Late-Onset Neonatal Sepsis: Current Strategies and Future Prospects

Neonatal sepsis is a clinical syndrome mainly associated with a bacterial infection leading to severe clinical manifestations that could be associated with fatal sequalae. According to the time of onset, neonatal sepsis is categorized as early- (EOS) or late-onset sepsis (LOS). Despite blood culture being the gold standard for diagnosis, it has several limitations, and early diagnosis is not immediate. Consequently, most infants who start empirical antimicrobial therapy do not have an underlying infection. Despite stewardship programs partially reduced this negative trend, in neonatology, antibiotic overuse still persists, and it is associated with several relevant problems, the first of which is the increase in antimicrobial resistance (AMR). Starting with these considerations, we performed a narrative review to summarize the main findings and the future prospects regarding antibiotics use to treat neonatal sepsis. Because of the impact on morbidity and mortality that EOS and LOS entail, it is essential to start an effective and prompt treatment as soon as possible. The use of targeted antibiotics is peremptory as soon as the pathogen in the culture is detected. Although prompt therapy is essential, it should be better assessed whether, when and how to treat neonates with antibiotics, even those at higher risk. Considering that we are certainly in the worrying era defined as the "post-antibiotic era", it is still essential and urgent to define novel strategies for the development of antibacterial compounds with new targets or mechanisms of action. A future strategy could also be to perform well-designed studies to develop innovative algorithms for improving the etiological diagnosis of infection, allowing for more personalized use of the antibiotics to treat EOS and LOS.

Life-threatening infections in human newborns: Reconciling age-specific vulnerability and interindividual variability

In humans, the interindividual variability of clinical outcome following exposure to a microorganism is immense, ranging from silent infection to life-threatening disease. Age-specific immune responses partially account for the high incidence of infection during the first 28 days of life and the related high mortality at population level. However, the occurrence of life-threatening disease in individual newborns remains unexplained. By contrast, inborn errors of immunity and their immune phenocopies are increasingly being discovered in children and adults with life-threatening viral, bacterial, mycobacterial and fungal infections. There is a need for convergence between the fields of neonatal immunology, with its in-depth population-wide characterization of newborn-specific immune responses, and clinical immunology, with its investigations of infections in patients at the cellular and molecular levels, to facilitate identification of the mechanisms of susceptibility to infection in individual newborns and the design of novel preventive and therapeutic strategies.

Factors Associated With Influenza Vaccination During Pregnancy: A Real-World Evidence-Based Study

Pregnant women are at increased risk of influenza-related complications. However, the rate of influenza vaccination among pregnant women in Taiwan is low. By analyzing real-world data in this study, we investigated the factors associated with influenza vaccination during pregnancy in Taiwan. This study was a cross-sectional study. We collected real-world data from 2 databases in Taiwan: the Birth Certificate Database and the National Health Insurance Research Database. The study population was pregnant between October 2014 and December 2016 in Taiwan. The multivariate logistic regression was performed to identify factors associated with influenza vaccination, including maternal sociodemographics, trimester, comorbidities, and health-care utilization. The vaccination rate of among pregnant women was 8.2%. Factors significantly associated with a high likelihood of influenza vaccination were age between 30 and 34 years (odds ratio [OR]: 1.14; 95% confidence interval [CI]: 1.10-1.19), second trimester (OR: 1.80; 95% CI: 1.75-1.85), income equal to or exceeding NT$ 38 201 (OR: 1.92; 95% CI: 1.86-1.99), hypertension (OR: 1.16; 95% CI: 1.05-1.29), cardiovascular disease (OR: 1.29; 95% CI: 1.17-1.42), autoimmune disease (OR: 1.47; 95% CI: 1.38-1.58), and chronic pulmonary disease (OR: 1.24; 95% CI: 1.18-1.31). A low level of urbanization, at least 1 hospitalization in the previous year, and the presence of pregnancy complications (eg, gestational diabetes, preeclampsia, and placenta previa) were associated with a lower likelihood rate of influenza vaccination. The influenza vaccination rate among pregnant women in Taiwan was low. Age, gestational age, income level, urbanization level, hypertension, cardiovascular disease, autoimmune disease, chronic pulmonary disease, and pregnancy complications may be associated with influenza vaccination among pregnant women.

Vaccine hesitancy and knowledge regarding maternal immunization among reproductive age women in central Italy: a cross sectional study

Background

Vaccination in pregnancy offers protection to the mother and the newborn. In Italy, influenza, pertussis, and COVID-19 vaccinations are recommended in pregnancy, but vaccination coverage is still far from the National Immunization Plan goals. We aimed to assess knowledge and attitude on maternal immunization in two groups of Italian women, in pregnancy and in reproductive age (non pregnant).

Methods

A cross sectional study on Italian childbearing age women gathering information on their knowledge on maternal immunization and attitudes to receiving influenza and pertussis vaccines in pregnancy was carried out at the University of Rome Tor Vergata, between September 2019 and February 2020. Logistic and multinomial regressions were chosen as statistical tests for our analysis.

Results

1,031 women participated in the survey by answering the questionnaire. Out of these, 553 (53.6%) women were pregnant, and 478 (46.4%) were in the reproductive age. 37% (204/553) of pregnant women and 41% (198/476) of non pregnant women are aware of the existence of an immunization plan for pregnant women in Italy. The group with age between 20 and 30, for both pregnant women and women in the reproductive age, has a better knowledge of vaccination in pregnancy. Working status is a variable associated with more awareness about vaccination during pregnancy only for pregnant women (OR = 2.34, p < 0.00001). Educational status, trimester of pregnancy and knowledge on the topic are associated with vaccine hesitancy in our multivariate analysis for pregnant women. In the reproductive age group women who had a previous pregnancy are more likely to be hesitant towards vaccination in pregnancy, on the other hand the one with a higher knowledge and educational status are more likely to get vaccinated.

Conclusions

The study highlights the persistent vaccine hesitancy among Italian women of reproductive age and pregnant women. Despite healthcare providers being identified as a reliable source of information, their recommendations alone are insufficient to overcome vaccine hesitancy. Factors such as employment status, educational level, pregnancy trimester, and knowledge about vaccinations during pregnancy influence vaccine hesitancy. Tailored educational interventions and communication campaigns targeting these areas can help reduce vaccine hesitancy and promote maternal immunization.

Transplacental delivery of therapeutic proteins by engineered immunoglobulin G: a step toward perinatal replacement therapy

BACKGROUND

Transplacental delivery of maternal immunoglobulin G (IgG) provides humoral protection during the first months of life until the newborn's immune system reaches maturity. The maternofetal interface has been exploited therapeutically to replace missing enzymes in the fetus, as shown in experimental mucopolysaccharidoses, or to shape adaptive immune repertoires during fetal development and induce tolerance to self-antigens or immunogenic therapeutic molecules.

OBJECTIVES

To investigate whether proteins that are administered to pregnant mice or endogenously present in their circulation may be delivered through the placenta.

METHODS

We engineered monovalent immunoglobulin G (FabFc) specific for different domains of human factor VIII (FVIII), a therapeutically relevant model antigen. FabFc was injected with exogenous FVIII into pregnant severe hemophilia A mice or pregnant mice expressing human FVIII following AAV8-mediated gene therapy. FabFc and FVIII were detected in the pregnant mice and/or fetuses by enzyme-linked immunosorbent assay and immunohistochemistry.

RESULTS

Administration of FabFc to pregnant mice allowed the maternofetal delivery of FVIII in a FcRn-dependent manner. FVIII antigen levels achieved in the fetuses represented 10% of normal plasma levels in the human. We identified antigen/FabFc complex stability, antigen size, and shielding of promiscuous protein patches as key parameters to foster optimal antigen delivery.

CONCLUSION

Our results pave the way toward the development of novel strategies for the in utero delivery of endogenous maternal proteins to replace genetically deficient fetal proteins or to educate the immune system and favor active immune tolerance upon protein encounter later in life.

Challenges of Diagnosing Mendelian Susceptibility to Mycobacterial Diseases in South Africa

Inborn errors of immunity (IEI) are genetic disorders with extensive clinical presentations. They can range from increased susceptibility to infections to significant immune dysregulation that results in immune impairment. While IEI cases are individually rare, they collectively represent a significant burden of disease, especially in developing countries such as South Africa, where infectious diseases like tuberculosis (TB) are endemic. This is particularly alarming considering that certain high penetrance mutations that cause IEI, such as Mendelian Susceptibility to Mycobacterial Disease (MSMD), put individuals at higher risk for developing TB and other mycobacterial diseases. MSMD patients in South Africa often present with different clinical phenotypes than those from the developed world, therefore complicating the identification of disease-associated variants in this setting with a high burden of infectious diseases. The lack of available data, limited resources, as well as variability in clinical phenotype are the reasons many MSMD cases remain undetected or misdiagnosed. This article highlights the challenges in diagnosing MSMD in South Africa and proposes the use of transcriptomic analysis as a means of potentially identifying dysregulated pathways in affected African populations.

Antenatal interventions to reduce risk of low birth weight related to maternal infections during pregnancy

BACKGROUND

Maternal infections during pregnancy have been linked to increased risk of adverse birth outcomes, including low birth weight (LBW), preterm birth (PTB), small for gestational age (SGA), and stillbirth (SB).

OBJECTIVES

The purpose of this article was to summarize evidence from published literature on the effect of key interventions targeting maternal infections on adverse birth outcomes.

METHODS

We searched MEDLINE, Embase, Cochrane Database of Systematic Reviews, Cochrane Central Register of Controlled Trials, and CINAHL Complete between March 2020 and May 2020 with an update to cover until August 2022. We included randomized controlled trials (RCTs) and reviews of RCTs of 15 antenatal interventions for pregnant women reporting LBW, PTB, SGA, or SB as outcomes.

RESULTS

Of the 15 reviewed interventions, the administration of 3 or more doses of intermittent preventive treatment in pregnancy with sulphadoxine-pyrimethamine [IPTp-SP; RR: 0.80 (95% CI: 0.69, 0.94)] can reduce risk of LBW compared with 2 doses. The provision of insecticide-treated bed nets, periodontal treatment, and screening and treatment of asymptomatic bacteriuria may reduce risk of LBW. Maternal viral influenza vaccination, treatment of bacterial vaginosis, intermittent preventive treatment with dihydroartemisinin-piperaquine compared with IPTp-SP, and intermittent screening and treatment of malaria during pregnancy compared with IPTp were deemed unlikely to reduce the prevalence of adverse birth outcomes.

CONCLUSIONS

At present, there is limited evidence from RCTs available for some potentially relevant interventions targeting maternal infections, which could be prioritized for future research.

Immune Response and Transplacental Antibody Transfer in Pregnant Women after COVID-19 Vaccination

COVID-19 infection is associated with increased risk of pregnancy complications, making vaccination during pregnancy critical for mother-neonate dyads. Few data, often with an unrepresentative sample size, are available on SARS-CoV-2 vaccine-induced humoral and cell-mediated response. Here, we evaluated anti-S antibody and interferon-gamma (IFN-γ) production elicited by SARS-CoV-2 immunization in maternal and neonatal plasma. Pregnant women (n = 230) were prospectively enrolled and classified as unvaccinated (n = 103) and vaccinated (n = 127); after serological screening for previous infections, assays were performed on 126 dyads, 15 mothers and 17 newborns. Positive anti-S antibodies were found in most of the vaccinated subjects, regardless of timespan between immunization and delivery (range: 7-391 days). A total of 89 of 92 vaccinated women showed a broad response to COVID-19 immunization and highly effective placental transfer, as attested by anti-S positive rates (maternal = 96.7%, cord = 96.6%). Most of our subjects had indeterminate results in an IGRA assay, preventing a conclusive evaluation of IFN-γ production. Indeed, pregnancy-related hormonal changes may influence T-cell response with an impact on IFN-γ production. Positive pregnancy and perinatal outcomes reinforce the evidence that the anti-SARS-CoV-2 immunization is effective and well-tolerated in pregnant women and also protective for the fetus/neonate, even though it was not possible to define the related IFN-γ production and role.

Prevention of Health Care–Associated Measles Transmission in a Pediatric Clinic

Objective Preventive measures in the setting of a suspected measles case in a hospital setting are important to stop the secondary spread. In this report, we evaluated the prevention attempts after two suspected cases of measles were reported in a pediatric clinic.

Methods We evaluated prevention interventions including isolation, intravenous immunoglobulin, or measles–mumps–rubella (MMR) vaccine after two patients were diagnosed with maculopapular rash compatible with measles in the pediatric clinic.

Results There were 50 patients (29 were outpatients, 21 were inpatients), 19 health care personnel (HCP), and 50 caregivers who were in contact with index cases. All of the HCP and 40 of the caregivers were immune to measles. Additional dose of MMR vaccine was recommended to five of the outpatients by phone. A total of 12 patients who were being followed up as inpatients (8 patients aged 6–12 months, 4 patients aged ≥ 12 months) were vaccinated with one dose of MMR vaccine. Only a 12-year-old male patient was admitted due to complaints suggesting measles after 14 days from discharge. It was learned that he had received a single dose of vaccine before so he was recommended an additional dose of MMR vaccine by the phone, but he did not go to the health institution on the day of the call.

Conclusion Postexposure prophylaxis is effective to prevent measles transmission. Although young infants have the highest risk for transmission of measles in a health care–associated outbreak, adolescents and older children who are single vaccinated also have high risk for clinical measles.

Effect of enterovirus 71 vaccination on the epidemiological characteristics and etiology in hospitalized children with hand-foot-and-mouth disease: A retrospective study from a tertiary children's hospital

Enterovirus 71 (EV71) vaccine for hand-foot-and-mouth disease (HFMD) prevention has been available for several years. However, as a new vaccine, the impact of EV71 vaccination on the epidemiology and etiology of HFMD is currently unclear. The purpose of this study was to compare and analyze the changes of epidemiological characteristics and etiology of HFMD patients after the introduction of EV71 vaccine. The data of hospitalized children with HFMD from 2014 to 2020 were collected from the case record department of a tertiary children hospital of Anhui Province. The changes of epidemiological characteristics, time distribution, disease severity and enterovirus serotypes in hospitalized children were analyzed. A total of 7373 cases of HFMD were reported during 2014 to 2020, including 634 (8.6%) severe cases. The number of cases reached the peak in 2016 (n = 1783) and decreased gradually after EV71 vaccination. The results of etiological test showed the positive rate was 80.5%, in which EV71 accounted for 1599 (21.7%) and CV-A16 accounted for 1028 (13.9%) respectively. The number of patients showed a bimodal distribution throughout the year, which were April to June and October to November. The age distribution changed significantly following the introduction of EV71 vaccine. The proportion of 1-year-old group of post-vaccination was significantly higher than that of pre-vaccination (61.9% vs 50.8%, P < .001). The proportion of HFMD caused by EV71 and severe cases decreased significantly after the vaccination (P < .001 for both). While the comparison of epidemiological characteristics and enterovirus serotypes between unvaccinated and vaccinated cases during 2017 to 2020 showed no significant difference. The dominant enterovirus serotypes of hospitalized HFMD changed significantly after the introduction of EV71 vaccine. The proportion of severe cases decreased significantly after the vaccination, but EV71 was still a major pathogen in patients with severe HFMD. More age-appropriate children are recommended to get vaccinated to establish stronger herd immunity in the population.

Maternal leucocyte trajectory across pregnancy associated with offspring's growth

BACKGROUND

Leucocytes for individuals during pregnancy may form into different trajectory patterns. Since no studies have been conducted, we aim to examine the associations between leucocyte trajectory across pregnancy and offspring's birth outcomes and growth during the first 2 years.

METHODS

We conducted a retrospective study enrolled 1070 singleton pregnancies aged 21-46 years old between 2014 and 2018 in Huazhong University of Science and Technology Union Shenzhen Hospital, China. Leucocyte trajectories were modelled using growth mixture modelling and four trajectories were identified: moderate-increasing (n = 41), low-stable (n = 828), high-decreasing (n = 145) and low-increasing (n = 56).

RESULTS

Relative to the low-stable group, logistic regression analysis after adjusting for covariates indicated that the odds ratios of preterm were 3.06 (95% confidence interval (CI): 1.43-6.23) for moderate-increasing, 0.78 (95% CI: 0.38-1.47) for high-decreasing and 0.68 (95% CI: 0.23-1.61) for the low-increasing group, respectively. By using generalized estimating equation analysis, we observed that infants in the moderate-increasing and low-increasing group had -0.35 and -0.21 (P &lt; 0.01) lower head circumference z-score compared with the low-stable group, respectively. No significant association of leucocyte trajectory with other birth weight measures or anthropometric measure z-scores was found.

CONCLUSIONS

Changes in leucocytes across pregnancy affected the occurrence of preterm and offspring's head circumference during the first 2 years of life.

IMPACT

Previous researches on the association of leucocytes with pregnancy outcomes mainly focused on leucocytes in a specific trimester. No studies until now have been conducted to assess the influences of the leucocyte trajectories on the growth and development of infants. Changes in leucocytes across pregnancy affected the occurrence of preterm and offspring's head circumference during the first 2 years of life. Our study will positively contribute to the dialogue regarding the treatment of pregnancies with different levels of inflammation in each trimester to minimize adverse pregnancy outcomes and optimize brain growth.

LAMP-1 Chimeric to HIV-1 p55Gag in the Immunization of Neonate Mice Induces an Early Germinal Center Formation and AID Expression

Neonates have a limited adaptive response of plasma cells, germinal center (GC) B cells, and T follicular helper cells (T_FH). As neonatal vaccination can be an important tool for AIDS prevention, these limitations need to be overcome. Chimeric DNA vaccine encoding p55Gag HIV-1 protein conjugated with lysosomal-associated membrane protein 1 (LAMP-1) has been described as immunogenic in the neonate period. Herein, we investigated the immunologic mechanisms involved in neonatal immunization with a LAMP-1/p55Gag (LAMP/Gag) DNA vaccine in a C57BL/6 mouse background. Neonatal LAMP/Gag vaccination induced strong Gag-specific T-cell response until adulthood and elevated levels of anti-Gag IgG antibodies. We also demonstrated for the first time that the immunogenicity of the neonatal period with LAMP/Gag is due to the induction of high-affinity anti-p24 IgG antibodies and long-term plasma cells. Together with that, there is the generation of early T_FH cells and the formation of GC sites with the upregulation of activation-induced cytidine deaminase (AID) enzyme mRNA and protein expression in draining lymph nodes after neonatal LAMP/Gag vaccination. These findings underscore that the LAMP-1 strategy in the chimeric vaccine could be useful to enhance antibody production even in the face of neonatal immaturity, and they contribute to the development of new vaccine approaches for other emerging pathogens at an early stage of life.

Modelling the impact of maternal pneumococcal vaccination on infant pneumococcal disease in low-income settings

Pneumococcal disease is a leading cause of mortality in young children. The largest burden of pneumococcal disease is in the first six months of life before protection from a complete schedule of direct immunisation is possible. Maternal pneumococcal vaccination has been proposed as a strategy for protection in this period of early childhood; however, limited clinical trial data exists. In this study, we developed an age-structured compartmental mathematical model to estimate the impact of maternal pneumococcal vaccination. Our model demonstrates how maternal pneumococcal vaccination could prevent 73% (range 49-88%) of cases in those aged <1 month and 55% (range 36-66%) in those 1-2 months old. This translates to an estimated 17% reduction in deaths due to invasive pneumococcal disease in children under five. Overall, this study demonstrates the potential for maternal pneumococcal vaccination to meaningfully reduce the burden of infant pneumococcal disease, supporting the case for appropriate field-based clinical studies.

Knowledge gaps in late-onset neonatal sepsis in preterm neonates: a roadmap for future research

Late-onset neonatal sepsis (LONS) remains an important threat to the health of preterm neonates in the neonatal intensive care unit. Strategies to optimize care for preterm neonates with LONS are likely to improve survival and long-term neurocognitive outcomes. However, many important questions on how to improve the prevention, early detection, and therapy for LONS in preterm neonates remain unanswered. This review identifies important knowledge gaps in the management of LONS and describe possible methods and technologies that can be used to resolve these knowledge gaps. The availability of computational medicine and hypothesis-free-omics approaches give way to building bedside feedback tools to guide clinicians in personalized management of LONS. Despite advances in technology, implementation in clinical practice is largely lacking although such tools would help clinicians to optimize many aspects of the management of LONS. We outline which steps are needed to get possible research findings implemented on the neonatal intensive care unit and provide a roadmap for future research initiatives. IMPACT: This review identifies knowledge gaps in prevention, early detection, antibiotic, and additional therapy of late-onset neonatal sepsis in preterm neonates and provides a roadmap for future research efforts. Research opportunities are addressed, which could provide the means to fill knowledge gaps and the steps that need to be made before possible clinical use. Methods to personalize medicine and technologies feasible for bedside clinical use are described.

Immune Response of Neonates Born to Mothers Infected With SARS-CoV-2

IMPORTANCE

Although several studies have provided information on short-term clinical outcomes in children with perinatal exposure to SARS-CoV-2, data on the immune response in the first months of life among newborns exposed to the virus in utero are lacking.

OBJECTIVE

To characterize systemic and mucosal antibody production during the first 2 months of life among infants who were born to mothers infected with SARS-CoV-2.

DESIGN, SETTING, AND PARTICIPANTS

This prospective cohort study enrolled 28 pregnant women who tested positive for SARS-CoV-2 infection and who gave birth at Policlinico Umberto I in Rome, Italy, from November 2020 to May 2021, and their newborns. Maternal and neonatal systemic immune responses were investigated by detecting spike-specific antibodies in serum, and the mucosal immune response was assessed by measuring specific antibodies in maternal breastmilk and infant saliva 48 hours after delivery and 2 months later.

EXPOSURES

Maternal infection with SARS-CoV-2 in late pregnancy.

MAIN OUTCOMES AND MEASURES

The systemic immune response was evaluated by the detection of SARS-CoV-2 IgG and IgA antibodies and receptor binding domain-specific IgM antibodies in maternal and neonatal serum. The mucosal immune response was assessed by measuring spike-specific antibodies in breastmilk and in infant saliva, and the presence of antigen-antibody spike IgA immune complexes was investigated in breastmilk samples. All antibodies were detected using an enzyme-linked immunosorbent assay.

RESULTS

In total, 28 mother-infant dyads (mean [SD] maternal age, 31.8 [6.4] years; mean [SD] gestational age, 38.1 [2.3] weeks; 18 [60%] male infants) were enrolled at delivery, and 21 dyads completed the study at 2 months' follow-up. Because maternal infection was recent in all cases, transplacental transfer of virus spike-specific IgG antibodies occurred in only 1 infant. One case of potential vertical transmission and 1 case of horizontal infection were observed. Virus spike protein-specific salivary IgA antibodies were significantly increased (P = .01) in infants fed breastmilk (0.99 arbitrary units [AU]; IQR, 0.39-1.68 AU) vs infants fed an exclusive formula diet (0.16 AU; IQR, 0.02-0.83 AU). Maternal milk contained IgA spike immune complexes at 48 hours (0.53 AU; IQR, 0.25-0.39 AU) and at 2 months (0.09 AU; IQR, 0.03-0.17 AU) and may have functioned as specific stimuli for the infant mucosal immune response.

CONCLUSIONS AND RELEVANCE

In this cohort study, SARS-CoV-2 spike-specific IgA antibodies were detected in infant saliva, which may partly explain why newborns are resistant to SARS-CoV-2 infection. Mothers infected in the peripartum period appear to not only passively protect the newborn via breastmilk secretory IgA but also actively stimulate and train the neonatal immune system via breastmilk immune complexes.

Atopic Manifestations in Children Born Preterm: A Long-Term Observational Study

(1) Background: Preterm birth exposes the infant to the known risk factors for atopic diseases. We aimed to study the neonatal risk factors and to describe the clinical manifestations of atopy, including the march of symptoms, in a cohort of preschool children born preterm. (2) Methods: We enrolled neonates with gestational age < 32 weeks or birth weight < 1500 g. We classified patients in cases and controls according to the presence of at least one atopic manifestation. (3) Results: We observed 72 cases and 93 controls. Multivariate models showed that the administration of more than one cycle of antibiotics (B 0.902, p = 0.026) and gestational diabetes (B 1.207, p = 0.035) influence the risk of atopy in babies born preterm. In addition, risk of atopic dermatitis was influenced by gestational age < 29 weeks (B -1.710, p = 0.025) and gestational diabetes (B 1.275, p = 0.027). The risk of wheeze was associated with familiarity for asthma (B 1.392, p = 0.022) and the administration of more than one cycle of antibiotics (B 0.969, p = 0.025). We observed a significant reduction in the rate of atopic manifestation after 2 years of life (33.9% vs. 23.8%, p < 0.05). (4) Conclusions: Modifiable (gestational diabetes, antibiotics use) and unmodifiable (familiarity for asthma) conditions influence the risk of atopy in babies born preterm. Extreme prematurity reduces the risk of atopic dermatitis. Preterm babies showed a peculiar atopic march.