Nasopharyngeal microbiota in children is associated with severe asthma exacerbations.

BACKGROUND: The respiratory microbiome has been associated with the etiology and disease course of asthma. OBJECTIVE: We sought to assess the nasopharyngeal microbiota in children with a severe asthma exacerbation and their associations with medication, air quality, and viral infection. METHODS: A cross-sectional study was performed among children aged 2 to 18 years admitted to the medium care unit (MCU; n = 84) or intensive care unit (ICU; n = 78) with an asthma exacerbation. For case-control analyses, we matched all cases aged 2 to 6 years (n = 87) to controls in a 1:2 ratio. Controls were participants of either a prospective case-control study or a longitudinal birth cohort (n = 182). The nasopharyngeal microbiota was characterized by 16S-rRNA-gene sequencing. RESULTS: Cases showed higher Shannon diversity index (ICU and MCU combined; P = .002) and a distinct microbial community composition when compared with controls (permutational multivariate ANOVA R2 = 1.9%; P < .001). We observed significantly higher abundance of Staphylococcus and "oral" taxa, including Neisseria, Veillonella, and Streptococcus spp. and a lower abundance of Dolosigranulum pigrum, Corynebacterium, and Moraxella spp. (MaAsLin2; q < 0.25) in cases versus controls. Furthermore, Neisseria abundance was associated with more severe disease (ICU vs MCU MaAslin2, P = .03; q = 0.30). Neisseria spp. abundance was also related with fine particulate matter exposure, whereas Haemophilus and Streptococcus abundances were related with recent inhaled corticosteroid use. We observed no correlations with viral infection. CONCLUSIONS: Our results demonstrate that children admitted with asthma exacerbations harbor a microbiome characterized by overgrowth of Staphylococcus and "oral" microbes and an underrepresentation of beneficial niche-appropriate commensals. Several of these associations may be explained by (environmental or medical) exposures, although cause-consequence relationships remain unclear and require further investigations.

Higher-valency pneumococcal conjugate vaccines in older adults, taking into account indirect effects from childhood vaccination: a cost-effectiveness study for the Netherlands.

BACKGROUND: New 15- and 20-valent pneumococcal vaccines (PCV15, PCV20) are available for both children and adults, while PCV21 for adults is in development. However, their cost-effectiveness for older adults, taking into account indirect protection and serotype replacement from a switch to PCV15 and PCV20 in childhood vaccination, remains unexamined. METHODS: We used a static model for the Netherlands to assess the cost-effectiveness of different strategies with 23-valent pneumococcal polysaccharide vaccine (PPV23), PCV15, PCV20, and PCV21 for a 65-year-old cohort from a societal perspective, over a 15-year time horizon. Childhood vaccination was varied from PCV10 to PCV13, PCV15, and PCV20. Indirect protection was assumed to reduce the incidence of vaccine serotypes in older adults by 80% (except for serotype 3, no effect), completely offset by an increase in non-vaccine serotype incidence due to serotype replacement. RESULTS: Indirect effects from childhood vaccination reduced the cost-effectiveness of vaccination of older adults, depending on the serotype overlap between the vaccines. With PCV10, PCV13, or PCV15 in children, PCV20 was more effective and less costly for older adults than PPV23 and PCV15. PCV20 costs approximately €10,000 per quality-adjusted life year (QALY) gained compared to no pneumococcal vaccination, which falls below the conventional Dutch €20,000/QALY gained threshold. However, with PCV20 in children, PCV20 was no longer considered cost-effective for older adults, costing €22,550/QALY gained. As indirect effects progressed over time, the cost-effectiveness of PCV20 for older adults further diminished for newly vaccinated cohorts. PPV23 was more cost-effective than PCV20 for cohorts vaccinated 3 years after the switch to PCV20 in children. PCV21 offered the most QALY gains, and its cost-effectiveness was minimally affected by indirect effects due to its coverage of 11 different serotypes compared to PCV20. CONCLUSIONS: For long-term cost-effectiveness in the Netherlands, the pneumococcal vaccine for older adults should either include invasive serotypes not covered by childhood vaccination or become more affordable than its current pricing for individual use.

Impact of age on pneumococcal colonization of the nasopharynx and oral cavity: an ecological perspective.

Pneumococcal carriage studies have suggested that pneumococcal colonization in adults is largely limited to the oral cavity and oropharynx. In this study, we used total abundance-based ß-diversity (dissimilarity) and ß-diversity components to characterize age-related differences in pneumococcal serotype composition of respiratory samples. quantitative PCR (qPCR) was applied to detect pneumococcal serotypes in nasopharyngeal samples collected from 946 toddlers and 602 adults, saliva samples collected from a subset of 653 toddlers, and saliva and oropharyngeal samples collected from a subset of 318 adults. Bacterial culture rates from nasopharyngeal samples were used to characterize age-related differences in rates of colonizing bacteria. Dissimilarity in pneumococcal serotype composition was low among saliva and nasopharyngeal samples from children. In contrast, respiratory samples from adults exhibited high serotype dissimilarity, which predominantly consisted of abundance gradients and was associated with reduced nasopharyngeal colonization. Age-related serotype dissimilarity was high among nasopharyngeal samples and relatively low for saliva samples. Reduced nasopharyngeal colonization by pneumococcal serotypes coincided with significantly reduced Moraxella catarrhalis and Haemophilus influenzae and increased Staphylococcus aureus nasopharyngeal colonization rates among adults. Findings from this study suggest that within-host environmental conditions, utilized in the upper airways by pneumococcus and other bacteria, undergo age-related changes. It may result in a host-driven ecological succession of bacterial species colonizing the nasopharynx and lead to competitive exclusion of pneumococcus from the nasopharynx but not from the oral habitat. This explains the poor performance of nasopharyngeal samples for pneumococcal carriage among adults and indicates that in adults saliva more accurately represents the epidemiology of pneumococcal carriage than nasopharyngeal samples.

Effect of Palivizumab Prophylaxis on Respiratory Syncytial Virus Infection in Very Preterm Infants in the First Year of Life in The Netherlands.

Respiratory Syncytial Virus (RSV) poses a severe threat to infants, particularly preterm infants. Palivizumab, the standard preventive prophylaxis, is primarily utilized in high-risk newborns due to its cost. This study assessed palivizumab's effectiveness in preventing RSV infections in predominantly very preterm infants during their first year of life. Serum samples from a prospective multicentre cohort study in the Netherlands were analyzed to assess RSV infection rates by measuring IgG levels against three RSV proteins: nucleoprotein, pre-fusion, and post-fusion protein. Infants were stratified based on gestational age (GA), distinguishing very preterm (≤32 weeks GA) from moderate/late preterm (>32 to ≤36 weeks GA). In very preterm infants, palivizumab prophylaxis significantly reduced infection rates (18.9% vs. 48.3% in the prophylaxis vs. non-prophylaxis group. Accounting for GA, sex, birth season, and birth weight, the prophylaxis group showed significantly lower infection odds. In infants with >32 to ≤36 weeks GA, the non-prophylaxis group (55.4%) showed infection rates similar to the non-prophylaxis ≤32-week GA group, despite higher maternal antibody levels in the moderate/late preterm infants. In conclusion, palivizumab prophylaxis significantly reduces RSV infection rates in very premature infants. Future research should explore clinical implications and reasons for non-compliance, and compare palivizumab with emerging prophylactics like nirsevimab aiming to optimize RSV prophylaxis and improve preterm infant outcomes.

Saliva as an alternative sample type for detection of pneumococcal carriage in young children.

For children, the gold standard for the detection of pneumococcal carriage is conventional culture of a nasopharyngeal swab. Saliva, however, has a history as one of the most sensitive methods for surveillance of pneumococcal colonization and has recently been shown to improve carriage detection in older age groups. Here, we compared the sensitivity of paired nasopharyngeal and saliva samples from PCV7-vaccinated 24-month-old children for pneumococcal carriage detection using conventional and molecular detection methods. Nasopharyngeal and saliva samples were collected from 288 24-month-old children during the autumn/winter, 2012/2013. All samples were first processed by conventional diagnostic culture. Next, DNA extracted from all plate growth was tested by qPCR for the presence of the pneumococcal genes piaB and lytA and a subset of serotypes. By culture, 161/288 (60 %) nasopharyngeal swabs tested positive for pneumococcus, but detection was not possible from saliva due to abundant polymicrobial growth on culture plates. By qPCR, 155/288 (54 %) culture-enriched saliva samples and 187/288 (65 %) nasopharyngeal swabs tested positive. Altogether, 219/288 (76 %) infants tested positive for pneumococcus, with qPCR-based carriage detection of culture-enriched nasopharyngeal swabs detecting significantly more carriers compared to either conventional culture (P<0.001) or qPCR detection of saliva (P=0.002). However, 32/219 (15 %) carriers were only positive in saliva, contributing significantly to the overall number of carriers detected (P=0.002). While testing nasopharyngeal swabs by qPCR proved most sensitive for pneumococcal detection in infants, saliva sampling could be considered as complementary to provide additional information on carriage and serotypes that may not be detected in the nasopharynx and may be particularly useful in longitudinal studies, requiring repeated sampling of study participants.

Maternal and neonatal antibody levels on pertussis vaccination in pregnant women on immune-modulating therapy for rheumatic disease.

OBJECTIVES: While protection against pertussis following maternal tetanus-diphtheria-and-acellular-pertussis (Tdap) vaccination was demonstrated in healthy term-born infants, no evidence is available on Tdap vaccination in combination with immune-modulating therapy during pregnancy. In this pilot study, we explored whether treatment with tumour necrosis factor alpha inhibitors (TNFis) in pregnant patients with rheumatic disease interferes with Tdap vaccine responses and affects maternal anti-pertussis IgG antibody levels in newborns. METHODS: Patients were included by a rheumatologist during pregnancy in case they received maternal Tdap vaccination in the late-second or early-third trimester of pregnancy. Blood samples were obtained from mothers during the first pregnancy trimester, 3 months after delivery and from the umbilical cord. IgG antibody levels against Tdap-included antigens were measured using a bead-based multiplex immunoassay. Findings on patients exposed to TNFis were compared with those from TNFi-unexposed patients and with data from a historical comparator study among healthy Tdap vaccinated mother-infant pairs (n=53). RESULTS: 66 patients (46 exposed and 20 unexposed to TNFIs) were enrolled. No major differences in IgG antibody levels were observed between TNFi-exposed and unexposed mothers before maternal Tdap vaccination and 3 months after delivery. In cord sera, however, antibody levels against pertussis toxin were significantly lower after TNFi-treatment (35.94 IU/mL, 95% CI 20.68 to 62.45) compared with no TNFi-treatment of mothers with rheumatic disease (94.61 IU/mL, 95% CI 48.89 to 183.07) and lower compared with a cohort of healthy mothers (125.12 IU/mL, 95% CI 90.75 to 172.50). We observed similar differences for filamentous haemagglutinin, pertactin, tetanus toxoid and diphtheria toxoid. CONCLUSION: These preliminary data indicate no major differences in IgG antibody levels on maternal Tdap vaccination in pregnant women with or without immune-modulating treatment, although our findings suggest that TNFis during pregnancy induce lower maternal anti-pertussis-specific protective antibody levels in newborns.

Antibody deficiencies in children are associated with prematurity and a family history of infections.

BACKGROUND: Recurrent respiratory tract infections (rRTIs) frequently affect young children and are associated with antibody deficiencies. We investigated the prevalence of and epidemiological risk factors associated with antibody deficiencies in young children with rRTIs and their progression over time, and linked these to prospectively measured RTI symptoms. METHODS: We included children <7 years with rRTIs in a prospective cohort study. Patient characteristics associated with antibody deficiencies were identified using multivariable logistic regression analysis. RESULTS: We included 146 children with a median age of 3.1 years. Daily RTI symptoms were monitored in winter in n = 73 children and repeated immunoglobulin level measurements were performed in n = 45 children. Antibody deficiency was diagnosed in 56% and associated with prematurity (OR 3.17 [1.15-10.29]) and a family history of rRTIs (OR 2.37 [1.11-5.15]). Respiratory symptoms did not differ between children with and without antibody deficiencies. During follow-up, antibody deficiency diagnosis remained unchanged in 67%, while 18% of children progressed to a more severe phenotype. CONCLUSION: Immune maturation and genetic predisposition may lie at the basis of antibody deficiencies commonly observed in early life. Because disease severity did not differ between children with and without antibody deficiency, we suggest symptom management can be similar for all children with rRTIs. IMPACT: An antibody deficiency was present in 56% of children <7 years with recurrent respiratory tract infections (rRTIs) in a Dutch tertiary hospital setting. Prematurity and a family history of rRTIs were associated with antibody deficiencies, suggesting that immune maturation and genetic predisposition may lie at the basis of antibody deficiencies in early life. RTI symptoms did not differ between children with and without antibody deficiency, suggesting that symptom management can be similar for all children with rRTIs, irrespective of humoral immunological deficiencies. During follow-up, 18% of children progressed to a more severe phenotype, emphasizing that early diagnosis is warranted to prevent long-term morbidity and increase quality of life.

A spitting image: molecular diagnostics applied to saliva enhance detection of Streptococcus pneumoniae and pneumococcal serotype carriage.

Background: Despite strong historical records on the accuracy of saliva testing, oral fluids are considered poorly suited for pneumococcal carriage detection. We evaluated an approach for carriage surveillance and vaccine studies that increases the sensitivity and specificity of pneumococcus and pneumococcal serotype detection in saliva samples. Methods: Quantitative PCR (qPCR)-based methods were applied to detect pneumococcus and pneumococcal serotypes in 971 saliva samples collected from 653 toddlers and 318 adults. Results were compared with culture-based and qPCR-based detection in nasopharyngeal samples collected from children and in nasopharyngeal and oropharyngeal samples collected from adults. Optimal C q cut-offs for positivity in qPCRs were determined via receiver operating characteristic curve analysis and accuracy of different approaches was assessed using a composite reference for pneumococcal and for serotype carriage based on isolation of live pneumococcus from the person or positivity of saliva samples determined with qPCR. To evaluate the inter-laboratory reproducibility of the method, 229 culture-enriched samples were tested independently in the second center. Results: In total, 51.5% of saliva samples from children and 31.8% of saliva samples from adults were positive for pneumococcus. Detection of pneumococcus by qPCR in culture-enriched saliva exhibited enhanced sensitivity and higher agreement with a composite reference compared to diagnostic culture of nasopharyngeal samples in children (Cohen's κ: 0.69-0.79 vs. 0.61-0.73) and in adults (κ: 0.84-0.95 vs. 0.04-0.33) and culture of oropharyngeal samples in adults (κ: 0.84-0.95 vs. -0.12-0.19). Similarly, detection of serotypes with qPCR in culture-enriched saliva exhibited enhanced sensitivity and higher agreement with a composite reference compared to nasopharyngeal culture in children (κ: 0.73-0.82 vs. 0.61-0.73) and adults (κ: 0.90-0.96 vs. 0.00-0.30) and oropharyngeal culture in adults (κ: 0.90-0.96 vs. -0.13 to 0.30). However, results of qPCRs targeting serotype 4, 5, and 17F and serogroups 9, 12, and 35 were excluded due to assays' lack of specificity. We observed excellent quantitative agreement for qPCR-based detection of pneumococcus between laboratories. After exclusion of serotype/serogroup-specific assays with insufficient specificity, moderate agreement (κ 0.68, 95% CI 0.58-0.77) was observed. Conclusion: Molecular testing of culture-enriched saliva samples improves the sensitivity of overall surveillance of pneumococcal carriage in children and adults, but limitations of qPCR-based approaches for pneumococcal serotypes carriage detection should be considered.

Meningococcal ACWY conjugate vaccine immunogenicity and safety in adolescents with juvenile idiopathic arthritis and inflammatory bowel disease: A prospective observational cohort study.

BACKGROUND: Immunogenicity to meningococcal serogroup ACWY (MenACWY) conjugate vaccine has not been studied in immunocompromised minors with juvenile idiopathic arthritis (JIA) or inflammatory bowel disease (IBD). We determined immunogenicity of a MenACWY-TT vaccine in JIA and IBD patients at adolescent age and compared results to data from aged-matched healthy controls (HCs). METHODS: We performed a prospective observational cohort study in JIA and IBD patients (14-18 years old), who received a MenACWY vaccination during a nationwide catch-up campaign (2018-2019) in the Netherlands. Primary aim was to compare MenACWY polysaccharide-specific serum IgG geometric mean concentrations (GMCs) in patients with HCs and secondary between patients with or without anti-TNF therapy. GMCs were determined before and 3-6, 12, and 24 months postvaccination and compared with data from HCs at baseline and 12 months postvaccination. Serum bactericidal antibody (SBA) titers were determined in a subset of patients at 12 months postvaccination. RESULTS: We included 226 JIA and IBD patients (66 % and 34 % respectively). GMCs were lower for MenA and MenW (GMC ratio 0·24 [0·17-0·34] and 0·16 [0·10-0·26] respectively, p < 0·01) in patients compared to HCs at 12 months postvaccination. Anti-TNF users had lower MenACWY GMCs postvaccination compared with those without anti-TNF (p < 0·01). The proportion protected (SBA ≥ 8) for MenW was reduced in anti-TNF users (76 % versus 92 % in non-anti-TNF and 100 % in HCs, p < 0.01). CONCLUSION: The MenACWY conjugate vaccine was immunogenic in the vast majority of JIA and IBD patients at adolescent age, but seroprotection was lower in patients using anti-TNF agents. Therefore, an extra booster MenACWY vaccination should be considered.

16S rRNA-Based Microbiota Profiling Assists Conventional Culture Analysis of Airway Samples from Pediatric Cystic Fibrosis Patients.

16S-based sequencing provides broader information on the respiratory microbial community than conventional culturing. However, it (often) lacks species- and strain-level information. To overcome this issue, we used 16S rRNA-based sequencing results from 246 nasopharyngeal samples obtained from 20 infants with cystic fibrosis (CF) and 43 healthy infants, which were all 0 to 6 months old, and compared them to both standard (blind) diagnostic culturing and a 16S-sequencing-informed "targeted" reculturing approach. Using routine culturing, we almost uniquely detected Moraxella catarrhalis, Staphylococcus aureus, and Haemophilus influenzae (42%, 38%, and 33% of samples, respectively). Using the targeted reculturing approach, we were able to reculture 47% of the top-5 operational taxonomical units (OTUs) in the sequencing profiles. In total, we identified 60 species from 30 genera with a median of 3 species per sample (range, 1 to 8). We also identified up to 10 species per identified genus. The success of reculturing the top-5 genera present from the sequencing profile depended on the genus. In the case of Corynebacterium being in the top 5, we recultured them in 79% of samples, whereas for Staphylococcus, this value was only 25%. The success of reculturing was also correlated with the relative abundance of those genera in the corresponding sequencing profile. In conclusion, revisiting samples using 16S-based sequencing profiles to guide a targeted culturing approach led to the detection of more potential pathogens per sample than conventional culturing and may therefore be useful in the identification and, consequently, treatment of bacteria considered relevant for the deterioration or exacerbation of disease in patients like those with CF. IMPORTANCE Early and effective treatment of pulmonary infections in cystic fibrosis is vital to prevent chronic lung damage. Although microbial diagnostics and treatment decisions are still based on conventional culture methods, research is gradually focusing more on microbiome and metagenomic-based approaches. This study compared the results of both methods and proposed a way to combine the best of both worlds. Many species can relatively easily be recultured based on the 16S-based sequencing profile, and it provides more in-depth information about the microbial composition of a sample than that obtained through routine (blind) diagnostic culturing. Still, well-known pathogens can be missed by both routine diagnostic culture methods as well as by targeted reculture methods, sometimes even when they are highly abundant, which may be a consequence of either sample storage conditions or antibiotic treatment at the time of sampling.

Mother-to-infant microbiota transmission and infant microbiota development across multiple body sites.

Early-life microbiota seeding and subsequent development is crucial to future health. Cesarean-section (CS) birth, as opposed to vaginal delivery, affects early mother-to-infant transmission of microbes. Here, we assess mother-to-infant microbiota seeding and early-life microbiota development across six maternal and four infant niches over the first 30 days of life in 120 mother-infant pairs. Across all infants, we estimate that on average 58.5% of the infant microbiota composition can be attributed to any of the maternal source communities. All maternal source communities seed multiple infant niches. We identify shared and niche-specific host/environmental factors shaping the infant microbiota. In CS-born infants, we report reduced seeding of infant fecal microbiota by maternal fecal microbes, whereas colonization with breastmilk microbiota is increased when compared with vaginally born infants. Therefore, our data suggest auxiliary routes of mother-to-infant microbial seeding, which may compensate for one another, ensuring that essential microbes/microbial functions are transferred irrespective of disrupted transmission routes.

Effectiveness of analgesic ear drops as add-on treatment to oral analgesics in children with acute otitis media: study protocol of the OPTIMA pragmatic randomised controlled trial.

INTRODUCTION: Ear pain is the most prominent symptom of childhood acute otitis media (AOM). To control the pain and reduce reliance on antibiotics, evidence of effectiveness for alternative interventions is urgently needed. This trial aims to investigate whether analgesic ear drops added to usual care provide superior ear pain relief over usual care alone in children presenting to primary care with AOM. METHODS AND ANALYSIS: This is a pragmatic, two-arm, individually randomised, open, superiority trial with cost-effectiveness analysis and nested mixed-methods process evaluation in general practices in the Netherlands. We aim to recruit 300 children aged 1-6 years with a general practitioner (GP) diagnosis of AOM and ear pain. Children will be randomly allocated (ratio 1:1) to either (1) lidocaine hydrochloride 5 mg/g ear drops (Otalgan) one to two drops up to six times daily for a maximum of 7 days in addition to usual care (oral analgesics, with/without antibiotics); or (2) usual care. Parents will complete a symptom diary for 4 weeks as well as generic and disease-specific quality of life questionnaires at baseline and 4 weeks. The primary outcome is the parent-reported ear pain score (0-10) over the first 3 days. Secondary outcomes include proportion of children consuming antibiotics, oral analgesic use and overall symptom burden in the first 7 days; number of days with ear pain, number of GP reconsultations and subsequent antibiotic prescribing, adverse events, complications of AOM and cost-effectiveness during 4-week follow-up; generic and disease-specific quality of life at 4 weeks; parents' and GPs' views and experiences with treatment acceptability, usability and satisfaction. ETHICS AND DISSEMINATION: The Medical Research Ethics Committee Utrecht, the Netherlands, has approved the protocol (21-447/G-D). All parents/guardians of participants will provide written informed consent. Study results will be submitted for publication in peer-reviewed medical journals and presented at relevant (inter)national scientific meetings. TRIAL REGISTRATION: The Netherlands Trial Register: NL9500; date of registration: 28 May 2021. At the time of publication of the study protocol paper, we were unable to make any amendments to the trial registration record in the Netherlands Trial Register. The addition of a data sharing plan was required to adhere to the International Committee of Medical Journal Editors guidelines. The trial was therefore reregistered in ClinicalTrials.gov (NCT05651633; date of registration: 15 December 2022). This second registration is for modification purposes only and the Netherlands Trial Register record (NL9500) should be regarded as the primary trial registration.

Reactogenicity and safety of second trimester maternal tetanus, diphtheria and acellular pertussis vaccination in the Netherlands.

BACKGROUND: Maternal tetanus-diphtheria-and-acellular-pertussis (Tdap) vaccination is offered to all pregnant women during their second trimester in the Netherlands since December 2019. We assessed second trimester Tdap vaccination reactogenicity and compared with third trimester data from a similar study. For safety assessment, adverse pregnancy outcomes were compared with national data from 2018, before Tdap vaccine-introduction. METHODS: Pregnant women were included between August 2019-December 2021 and received Tdap vaccination between 20 and 24w gestational age (GA). Participants completed a questionnaire on solicited local reactions and systemic adverse events (AEs) within one week after vaccination. Results were compared with historical data on reactogenicity from women vaccinated between 30 and 33w GA (n = 58). Regarding safety-related outcomes, each participant was matched to four unvaccinated pregnant women from the Dutch Perinatal Registry, based on living area, parity and age. RESULTS: Among 723 participants who completed the questionnaire, 488 (67.5 %) experienced ≥ 1 local reaction with pain at the injection site as most reported reaction (62.3 %), and 460 (63.6 %) experienced ≥ 1 systemic AE with stiffness in muscles/joints (38.9 %), fatigue (28.9 %), headache (14.5 %) and common cold-like symptoms (11.0 %) most frequently reported. 4 women (0.6 %) reported fever (≥38.0˚C). Symptoms were considered mild and transient within days. No difference in AEs were found between vaccination at 20-24w versus 30-33w GA. 723 participants were matched to 2,424 unvaccinated pregnant women with no increased rates of premature labor, small-for-gestational-age, or other adverse pregnancy outcomes. CONCLUSIONS: Second trimester maternal Tdap vaccination appears safe and well-tolerated. Comparison between second versus third trimester vaccination yielded no reactogenicity concerns.

Asymptomatic Viral Presence in Early Life Precedes Recurrence of Respiratory Tract Infections.

BACKGROUND: Respiratory tract infections (RTIs) in infants are often caused by viruses. Although respiratory syncytial virus (RSV), influenza virus and human metapneumovirus (hMPV) can be considered the most pathogenic viruses in children, rhinovirus (RV) is often found in asymptomatic infants as well. Little is known about the health consequences of viral presence, especially early in life. We aimed to examine the dynamics of (a)symptomatic viral presence and relate early viral detection to susceptibility to RTIs in infants. METHODS: In a prospective birth cohort of 117 infants, we tested 1304 nasopharyngeal samples obtained from 11 consecutive regular sampling moments, and during acute RTIs across the first year of life for 17 respiratory viruses by quantitative PCR. Associations between viral presence, viral (sub)type, viral load, viral co-detection and symptoms were tested by generalized estimating equation (GEE) models. RESULTS: RV was the most detected virus. RV was negatively associated [GEE: adjusted odds ratio (aOR) 0.41 (95% CI 0.18-0.92)], and hMPV, RSV, parainfluenza 2 and 4 and human coronavirus HKU1 were positively associated with an acute RTI. Asymptomatic RV in early life was, however, associated with increased susceptibility to and recurrence of RTIs later in the first year of life (Kaplan-Meier survival analysis: P = 0.022). CONCLUSIONS: Respiratory viruses, including the seasonal human coronaviruses, are often detected in infants, and are often asymptomatic. Early life RV presence is, though negatively associated with an acute RTI, associated with future susceptibility to and recurrence of RTIs. Further studies on potential ecologic or immunologic mechanisms are needed to understand these observations.

Mode of delivery modulates the intestinal microbiota and impacts the response to vaccination.

The gut microbiota in early life, when critical immune maturation takes place, may influence the immunogenicity of childhood vaccinations. Here we assess the association between mode of delivery, gut microbiota development in the first year of life, and mucosal antigen-specific antibody responses against pneumococcal vaccination in 101 infants at age 12 months and against meningococcal vaccination in 66 infants at age 18 months. Birth by vaginal delivery is associated with higher antibody responses against both vaccines. Relative abundances of vaginal birth-associated Bifidobacterium and Escherichia coli in the first weeks of life are positively associated with anti-pneumococcal antibody responses, and relative abundance of E. coli in the same period is also positively associated with anti-meningococcal antibody responses. In this study, we show that mode of delivery-induced microbiota profiles of the gut are associated with subsequent antibody responses to routine childhood vaccines.

Longitudinal Household Assessment of Respiratory Illness in Children and Parents During the COVID-19 Pandemic.

Importance: In the early COVID-19 pandemic, SARS-CoV-2 testing was only accessible and recommended for symptomatic persons or adults. This restriction hampered assessment of the true incidence of SARS-CoV-2 infection in children as well as detailed characterization of the SARS-CoV-2 disease spectrum and how this spectrum compared with that of other common respiratory illnesses. Objective: To estimate the community incidence of SARS-CoV-2 infection in children and parents and to assess the symptoms and symptom severity of respiratory illness episodes involving SARS-CoV-2-positive test results relative to those with SARS-CoV-2-negative test results. Design, Setting, and Participants: This cohort study randomly selected Dutch households with at least 1 child younger than 18 years. A total of 1209 children and adults from 307 households were prospectively followed up between August 25, 2020, and July 29, 2021, covering the second and third waves of the COVID-19 pandemic. Participation included SARS-CoV-2 screening at 4- to 6-week intervals during the first 23 weeks of participation (core study period; August 25, 2020, to July 29, 2021). Participants in all households finishing the core study before July 1, 2021, were invited to participate in the extended follow-up and to actively report respiratory symptoms using an interactive app until July 1, 2021. At new onset of respiratory symptoms or a SARS-CoV-2 positive test result, a household outbreak study was initiated, which included daily symptom recording, repeated polymerase chain reaction testing (nose-throat swabs and saliva and fecal samples), and SARS-CoV-2 antibody measurement (paired dried blood spots) in all household members. Outbreaks, households, and episodes of respiratory illness were described as positive or negative depending on SARS-CoV-2 test results. Data on participant race and ethnicity were not reported because they were not uniformly collected in the original cohorts and were therefore not representative or informative. Exposures: SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Main Outcomes and Measures: Age-stratified incidence rates, symptoms, and symptom severity for SARS-CoV-2-positive and SARS-CoV-2-negative respiratory illness episodes. Results: Among 307 households including 1209 participants (638 female [52.8%]; 403 [33.3%] aged <12 years, 179 [14.8%] aged 12-17 years, and 627 [51.9%] aged ≥18 years), 183 household outbreaks of respiratory illness were observed during the core study and extended follow-up period, of which 63 (34.4%) were SARS-CoV-2 positive (59 outbreaks [32.2%] during the core study and 4 outbreaks [2.2%] during follow-up). SARS-CoV-2 incidence was similar across all ages (0.24/person-year [PY]; 95% CI, 0.21-0.28/PY). Overall, 33 of 134 confirmed SARS-CoV-2 episodes (24.6%) were asymptomatic. The incidence of SARS-CoV-2-negative respiratory illness episodes was highest in children younger than 12 years (0.94/PY; 95% CI, 0.89-0.97/PY). When comparing SARS-CoV-2-positive vs SARS-CoV-2-negative respiratory illness episodes in children younger than 12 years, no differences were observed in number of symptoms (median [IQR], 2 [2-4] for both groups), symptom severity (median [IQR] maximum symptom severity score, 6 [4-9] vs 7 [6-13]), or symptom duration (median [IQR], 6 [5-12] days vs 8 [4-13] days). However, among adults, SARS-CoV-2-positive episodes had a significantly higher number (median [IQR], 6 [4-8] vs 3 [2-4]), severity (median [IQR] maximum symptom severity score, 15 [9-19] vs 7 [6-11]), and duration (median [IQR] 13 [8-29] days vs 5 [3-11] days; P < .001 for all comparisons) of symptoms vs SARS-CoV-2-negative episodes. Conclusions and Relevance: In this cohort study, during the first pandemic year when mostly partial or full in-person learning occurred, the SARS-CoV-2 incidence rate in children was substantially higher than estimated from routine testing or seroprevalence data and was similar to that of adult household members. Unlike in unvaccinated adults, SARS-CoV-2 symptoms and symptom severity in children were similar to other common respiratory illnesses. These findings may prove useful when developing pediatric COVID-19 vaccine recommendations.

Pneumococcal genetic variability in age-dependent bacterial carriage.

The characteristics of pneumococcal carriage vary between infants and adults. Host immune factors have been shown to contribute to these age-specific differences, but the role of pathogen sequence variation is currently less well-known. Identification of age-associated pathogen genetic factors could leadto improved vaccine formulations. We therefore performed genome sequencing in a large carriage cohort of children and adults and combined this with data from an existing age-stratified carriage study. We compiled a dictionary of pathogen genetic variation, including serotype, strain, sequence elements, single-nucleotide polymorphisms (SNPs), and clusters of orthologous genes (COGs) for each cohort - all of which were used in a genome-wide association with host age. Age-dependent colonization showed weak evidence of being heritable in the first cohort (h2 = 0.10, 95% CI 0.00-0.69) and stronger evidence in the second cohort (h2 = 0.56, 95% CI 0.23-0.87). We found that serotypes and genetic background (strain) explained a proportion of the heritability in the first cohort (h2serotype = 0.07, 95% CI 0.04-0.14 and h2GPSC = 0.06, 95% CI 0.03-0.13) and the second cohort (h2serotype = 0.11, 95% CI 0.05-0.21 and h2GPSC = 0.20, 95% CI 0.12-0.31). In a meta-analysis of these cohorts, we found one candidate association (p=1.2 × 10-9) upstream of an accessory Sec-dependent serine-rich glycoprotein adhesin. Overall, while we did find a small effect of pathogen genome variation on pneumococcal carriage between child and adult hosts, this was variable between populations and does not appear to be caused by strong effects of individual genes. This supports proposals for adaptive future vaccination strategies that are primarily targeted at dominant circulating serotypes and tailored to the composition of the pathogen populations.

Memory B Cell Activation Induced by Pertussis Booster Vaccination in Four Age Groups of Three Countries.

Background: Immunogenicity of acellular pertussis (aP) vaccines is conventionally assessed by measuring antibody responses but antibody concentrations wane quickly after vaccination. Memory B cells, however, are critical in sustaining long-term protection and therefore may be an important factor when assessing pertussis immunity after vaccination. Aim: We studied pertussis specific memory B cell (re)activation induced by an aP booster vaccination in four different age groups within three countries. Materials and methods: From a phase IV longitudinal interventional study, 268 participants across Finland, the Netherlands and the United Kingdom were included and received a 3-component pertussis booster vaccine: children (7-10y, n=53), adolescents (11-15y, n=66), young adults (20-34y, n=74), and older adults (60-70y, n=75). Memory B cells at baseline, day 28, and 1 year post-vaccination were measured by a pertussis toxin (Ptx), filamentous haemagglutinin (FHA), and pertactin (Prn) specific ELISpot assay. Antibody results measured previously were available for comparison. Furthermore, study participants were distributed into groups based on their baseline memory B cell frequencies, vaccine responses were monitored between these groups. Results: Geometric mean (GM) memory B cell frequencies for pertussis antigens at baseline were low. At 28 days post-vaccination, these frequencies increased within each age group and were still elevated one year post-booster compared to baseline. Highest frequencies at day 28 were found within adolescents (GM: 5, 21, and 13, for Ptx, FHA and Prn, respectively) and lowest within older adults (GM: 2, 9, and 3, respectively). Moderate to strong correlations between memory B cell frequencies at day 28 and antibody concentrations at day 28 and 1 year were observed for Prn. Memory B cell frequencies > 1 per 100,000 PBMCs at baseline were associated with significantly higher memory responses after 28 days and 1 year. Conclusions: An aP booster vaccine (re)activated memory B cells in all age groups. Still elevated memory B cell frequencies after one year indicates enhanced immunological memory. However, antigen specific memory B cell activation seems weaker in older adults, which might reflect immunosenescence. Furthermore, the presence of circulating memory B cells at baseline positively affects memory B cell responses. This study was registered at www.clinicaltrialsregister.eu: No. 2016-003678-42.

It Takes Two to Tango: Combining Conventional Culture With Molecular Diagnostics Enhances Accuracy of Streptococcus pneumoniae Detection and Pneumococcal Serogroup/Serotype Determination in Carriage.

Background: The specificity of molecular methods for the detection of Streptococcus pneumoniae carriage is under debate. We propose a procedure for carriage surveillance and vaccine impact studies that increases the accuracy of molecular detection of live pneumococci in polymicrobial respiratory samples. Methods: Culture and qPCR methods were applied to detect pneumococcus and pneumococcal serotypes in 1,549 nasopharyngeal samples collected in the Netherlands (n = 972) and England (n = 577) from 946 toddlers and 603 adults, and in paired oropharyngeal samples collected exclusively from 319 Dutch adults. Samples with no live pneumococci isolated at primary diagnostic culture yet generating signal specific for pneumococcus in qPCRs were re-examined with a second, qPCR-guided culture. Optimal Cq cut-offs for positivity in qPCRs were determined via receiver operating characteristic (ROC) curve analysis using isolation of live pneumococci from the primary and qPCR-guided cultures as reference. Results: Detection of pneumococcus and pneumococcal serotypes with qPCRs in cultured (culture-enriched) nasopharyngeal samples exhibited near-perfect agreement with conventional culture (Cohen's kappa: 0.95). Molecular methods displayed increased sensitivity of detection for multiple serotype carriage, and implementation of qPCR-guided culturing significantly increased the proportion of nasopharyngeal and oropharyngeal samples from which live pneumococcus was recovered (p < 0.0001). For paired nasopharyngeal and oropharyngeal samples from adults none of the methods applied to a single sample type exhibited good agreement with results for primary and qPCR-guided nasopharyngeal and oropharyngeal cultures combined (Cohens kappa; 0.13-0.55). However, molecular detection of pneumococcus displayed increased sensitivity with culture-enriched oropharyngeal samples when compared with either nasopharyngeal or oropharyngeal primary cultures (p < 0.05). Conclusion: The accuracy of pneumococcal carriage surveillance can be greatly improved by complementing conventional culture with qPCR and vice versa, by using results of conventional and qPCR-guided cultures to interpret qPCR data. The specificity of molecular methods for the detection of live pneumococci can be enhanced by incorporating statistical procedures based on ROC curve analysis. The procedure we propose for future carriage surveillance and vaccine impact studies improves detection of pneumococcal carriage in adults in particular and enhances the specificity of serotype carriage detection.

Long-Term Immunogenicity upon Pertussis Booster Vaccination in Young Adults and Children in Relation to Priming Vaccinations in Infancy.

Booster vaccinations for pertussis are advised in many countries during childhood or adulthood. In a phase IV longitudinal interventional study, we assessed long-term immunity following an extra pertussis booster vaccination in children and adults. Children (9 years of age) were primed in infancy with either the Dutch whole cell pertussis (wP) vaccine (n = 49) or acellular pertussis (aP) vaccines (n = 59), and all children received a preschool aP booster. Adults (25-29 years, n = 86) were wP-primed in infancy and did not receive a preschool booster. All were followed-up for approximately 6 years. After the additional booster, antibody responses to pertussis were more heterogeneous but generally higher in adults compared with children, and additional modelling showed that antibody concentrations remained higher for at least a decade. Serologic parameters indicative of recent pertussis infection were more often found in aP-primed children (12%) compared with wP-primed individuals (2%) (p = 0.052). This suggests that the aP booster vaccination in aP-primed children offers less long-term protection against pertussis infection and consequently against transmission. Together, these data show that aP priming in combination with aP boosting may not be sufficient to prevent circulation and transmission, while wP-primed adults may benefit from enhanced long-lasting immunity.