Influenza Vaccination Coverage Rates and Determinants in Greek Children until the Age of Ten (2008-2019), the Rhea Mother-Child Cohort.

BACKGROUND: In Greece, influenza vaccination is currently recommended for children with high-risk conditions. There are limited data on influenza vaccination uptake among Greek children with and without high-risk conditions. We aim to describe the annual influenza vaccination uptake until the age of ten in a population-based mother-child cohort and identify the factors influencing vaccination rates. METHODS: Immunization data from the child's health cards at 4 and 10 years were available for 830 and 298 children participating in the Rhea cohort (2008-2019). We calculated vaccination coverage by age, winter season and among children with asthma and obesity for whom the vaccine is indicated. Univariable and multivariable stepwise logistic regression models were utilized to identify the association between several sociodemographic, lifestyle and health-related variables and vaccine uptake by age four. RESULTS: By the ages of four and ten, 37% and 40% of the children, respectively, had received at least one influenza vaccination. Only 2% of the children were vaccinated for all winter seasons during their first four years of life. The vaccination rate was highest at the age of two and during the 2009-2010 season. Vaccination rates for children with asthma and obesity were 18.2% and 13.3% at age four and 8.3% and 2.9% at age ten. About 10% of all vaccines were administered after December and 24% of the children received only one dose upon initial vaccination. Children with younger siblings and those who had experienced more respiratory infections were more likely to be vaccinated by the age of four, while children exposed to smoking were less likely to be vaccinated. CONCLUSIONS: Children in our study were more likely to be vaccinated against influenza at an early age with the peak occurring at the age of two. Nonetheless, annual vaccination uptake was uncommon. Vaccination rates of children with asthma and obesity were well below the national target of 75% for individuals with chronic conditions. Certain groups may merit increased attention in future vaccination campaigns such as children raised in families with unfavourable health behaviours.

Long-Term Exposure to Air Pollution and COVID-19 Vaccine Antibody Response in a General Population Cohort (COVICAT Study, Catalonia).

BACKGROUND: Ambient air pollution has been associated with COVID-19 disease severity and antibody response induced by infection. OBJECTIVES: We examined the association between long-term exposure to air pollution and vaccine-induced antibody response. METHODS: This study was nested in an ongoing population-based cohort, COVICAT, the GCAT-Genomes for Life cohort, in Catalonia, Spain, with multiple follow-ups. We drew blood samples in 2021 from 1,090 participants of 2,404 who provided samples in 2020, and we included 927 participants in this analysis. We measured immunoglobulin M (IgM), IgG, and IgA antibodies against five viral-target antigens, including receptor-binding domain (RBD), spike-protein (S), and segment spike-protein (S2) triggered by vaccines available in Spain. We estimated prepandemic (2018-2019) exposure to fine particulate matter [PM ≤2.5µm in aerodynamic diameter (PM2.5)], nitrogen dioxide (NO2), black carbon (BC), and ozone (O3) using Effects of Low-Level Air Pollution: A Study in Europe (ELAPSE) models. We adjusted estimates for individual- and area-level covariates, time since vaccination, and vaccine doses and type and stratified by infection status. We used generalized additive models to explore the relationship between air pollution and antibodies according to days since vaccination. RESULTS: Among vaccinated persons not infected by SARS-CoV-2 (n=632), higher prepandemic air pollution levels were associated with a lower vaccine antibody response for IgM (1 month post vaccination) and IgG. Percentage change in geometric mean IgG levels per interquartile range of PM2.5 (1.7 µg/m3) were -8.1 (95% CI: -15.9, 0.4) for RBD, -9.9 (-16.2, -3.1) for S, and -8.4 (-13.5, -3.0) for S2. We observed a similar pattern for NO2 and BC and an inverse pattern for O3. Differences in IgG levels by air pollution levels persisted with time since vaccination. We did not observe an association of air pollution with vaccine antibody response among participants with prior infection (n=295). DISCUSSION: Exposure to air pollution was associated with lower COVID-19 vaccine antibody response. The implications of this association on the risk of breakthrough infections require further investigation. https://doi.org/10.1289/EHP11989.

The Association of Time of Day of ChAdOx1 nCoV-19 Vaccine Administration With SARS-CoV-2 Anti-Spike IgG Antibody Levels: An Exploratory Observational Study.

Data from human and animal studies are highly suggestive of an influence of time of day of vaccine administration on host immune responses. In this population-based study, we aimed to investigate the effect of time of day of administration of a COVID-19 vector vaccine, ChAdOx1 nCoV-19 (AstraZeneca), on SARS-CoV-2 anti-spike S1 immunoglobulin (IgG) levels. Participants were 803 university employees who received their first vaccine dose in March 2021, had serology data at baseline and at 3 weeks, and were seronegative at baseline. Antibody levels were determined in binding antibody units (BAU/mL) using enzyme-linked immunosorbent assay (ELISA). Generalized additive models (GAM) and linear regression were used to evaluate the association of time of day of vaccination continuously and in hourly bins with antibody levels at 3 weeks. Participants had a mean age of 42 years (SD: 12; range: 21-74) and 60% were female. Time of day of vaccination was associated non-linearly ("reverse J-shape") with antibody levels. Morning vaccination was associated with the highest (9:00-10:00 h: mean 292.1 BAU/mL; SD: 262.1), early afternoon vaccination with the lowest (12:00-13:00 h: mean 217.3 BAU/mL; SD: 153.6), and late afternoon vaccination with intermediate (14:00-15:00 h: mean 280.7 BAU/mL; SD: 262.4) antibody levels. Antibody levels induced by 12:00-13:00 h vaccination (but not other time intervals) were significantly lower compared to 9:00-10:00 h vaccination after adjusting for potential confounders (beta coefficient = -75.8, 95% confidence interval [CI] = -131.3, -20.4). Our findings show that time of day of vaccination against SARS-CoV-2 has an impact on the magnitude of IgG antibody levels at 3 weeks. Whether this difference persists after booster vaccine doses and whether it influences the level of protection against COVID-19 needs further evaluation.

SARS-CoV-2 infection, vaccination, and antibody response trajectories in adults: a cohort study in Catalonia.

BACKGROUND: Heterogeneity of the population in relation to infection, COVID-19 vaccination, and host characteristics is likely reflected in the underlying SARS-CoV-2 antibody responses. METHODS: We measured IgM, IgA, and IgG levels against SARS-CoV-2 spike and nucleocapsid antigens in 1076 adults of a cohort study in Catalonia between June and November 2020 and a second time between May and July 2021. Questionnaire data and electronic health records on vaccination and COVID-19 testing were available in both periods. Data on several lifestyle, health-related, and sociodemographic characteristics were also available. RESULTS: Antibody seroreversion occurred in 35.8% of the 64 participants non-vaccinated and infected almost a year ago and was related to asymptomatic infection, age above 60 years, and smoking. Moreover, the analysis on kinetics revealed that among all responses, IgG RBD, IgA RBD, and IgG S2 decreased less within 1 year after infection. Among vaccinated, 2.1% did not present antibodies at the time of testing and approximately 1% had breakthrough infections post-vaccination. In the post-vaccination era, IgM responses and those against nucleoprotein were much less prevalent. In previously infected individuals, vaccination boosted the immune response and there was a slight but statistically significant increase in responses after a 2nd compared to the 1st dose. Infected vaccinated participants had superior antibody levels across time compared to naïve-vaccinated people. mRNA vaccines and, particularly the Spikevax, induced higher antibodies after 1st and 2nd doses compared to Vaxzevria or Janssen COVID-19 vaccines. In multivariable regression analyses, antibody responses after vaccination were predicted by the type of vaccine, infection age, sex, smoking, and mental and cardiovascular diseases. CONCLUSIONS: Our data support that infected people would benefit from vaccination. Results also indicate that hybrid immunity results in superior antibody responses and infection-naïve people would need a booster dose earlier than previously infected people. Mental diseases are associated with less efficient responses to vaccination.

Prenatal and infant antibiotic exposure and childhood growth, obesity and cardiovascular risk factors: The Rhea mother-child cohort study, Crete, Greece.

BACKGROUND: Early-life antibiotic use has been hypothesized to promote weight gain and increase the risk of childhood obesity. OBJECTIVES: To examine the associations of prenatal and infant antibiotics with childhood growth, adiposity and cardiometabolic traits in the Greek Rhea cohort. METHODS: We used data from 747 mother-child pairs with anthropometric measurements drawn from medical records or measured at 4 and 6 years of age. Antibiotic exposure was assessed by maternal report during pregnancy and at the first year of life. Children were classified as exposed to antibiotics prenatally if the mother received at least one course of oral antibiotics during pregnancy and postnatally if the mother reported that the child received at least one oral antibiotic treatment during the first year of life. Outcomes included repeated weight, body mass index (BMI), waist circumference, body fat (%), total cholesterol and blood pressure. We applied mixed effects, linear and log-binomial regression models after adjusting for important covariates. RESULTS: Around 14.6% of the participating children were prenatally exposed to antibiotics and 32.4% received antibiotics during the first year of life. Prenatal exposure to antibiotics was associated with a twofold increase in the risk for obesity (risk ratio [RR]; 95% confidence interval [CI]: 2.09 [1.58, 2.76]) and abdominal obesity (RR [95% CI]: 2.56 [1.89, 3.47]) at 6 years. Postnatal exposure to antibiotics was associated with increased weight (beta [95% CI]: 00.25 [0.06, 0.44]) and BMI (beta [95% CI]: 0.23 [0.003, 0.45]) SD scores from 2 to 7 years of life. CONCLUSION: Early-life antibiotic use was associated with accelerated childhood growth and higher adiposity.

Infection induced SARS-CoV-2 seroprevalence and heterogeneity of antibody responses in a general population cohort study in Catalonia Spain.

Sparse data exist on the complex natural immunity to SARS-CoV-2 at the population level. We applied a well-validated multiplex serology test in 5000 participants of a general population study in Catalonia in blood samples collected from end June to mid November 2020. Based on responses to fifteen isotype-antigen combinations, we detected a seroprevalence of 18.1% in adults (n = 4740), and modeled extrapolation to the general population of Catalonia indicated a 15.3% seroprevalence. Antibodies persisted up to 9 months after infection. Immune profiling of infected individuals revealed that with increasing severity of infection (asymptomatic, 1-3 symptoms, ≥ 4 symptoms, admitted to hospital/ICU), seroresponses were more robust and rich with a shift towards IgG over IgA and anti-spike over anti-nucleocapsid responses. Among seropositive participants, lower antibody levels were observed for those ≥ 60 years vs < 60 years old and smokers vs non-smokers. Overweight/obese participants vs normal weight had higher antibody levels. Adolescents (13-15 years old) (n = 260) showed a seroprevalence of 11.5%, were less likely to be tested seropositive compared to their parents and had dominant anti-spike rather than anti-nucleocapsid IgG responses. Our study provides an unbiased estimate of SARS-CoV-2 seroprevalence in Catalonia and new evidence on the durability and heterogeneity of post-infection immunity.

Ambient Air Pollution in Relation to SARS-CoV-2 Infection, Antibody Response, and COVID-19 Disease: A Cohort Study in Catalonia, Spain (COVICAT Study).

BACKGROUND: Emerging evidence links ambient air pollution with coronavirus 2019 (COVID-19) disease, an association that is methodologically challenging to investigate. OBJECTIVES: We examined the association between long-term exposure to air pollution with SARS-CoV-2 infection measured through antibody response, level of antibody response among those infected, and COVID-19 disease. METHODS: We contacted 9,605 adult participants from a population-based cohort study in Catalonia between June and November 2020; most participants were between 40 and 65 years of age. We drew blood samples from 4,103 participants and measured immunoglobulin M (IgM), IgA, and IgG antibodies against five viral target antigens to establish infection to the virus and levels of antibody response among those infected. We defined COVID-19 disease using self-reported hospital admission, prior positive diagnostic test, or more than three self-reported COVID-19 symptoms after contact with a COVID-19 case. We estimated prepandemic (2018-2019) exposure to fine particulate matter [PM with an aerodynamic diameter of ≤2.5µm (PM2.5)], nitrogen dioxide (NO2), black carbon (BC), and ozone (O3) at the residential address using hybrid land-use regression models. We calculated log-binomial risk ratios (RRs), adjusting for individual- and area-level covariates. RESULTS: Among those tested for SARS-CoV-2 antibodies, 743 (18.1%) were seropositive. Air pollution levels were not statistically significantly associated with SARS-CoV-2 infection: Adjusted RRs per interquartile range were 1.07 (95% CI: 0.97, 1.18) for NO2, 1.04 (95% CI: 0.94, 1.14) for PM2.5, 1.00 (95% CI: 0.92, 1.09) for BC, and 0.97 (95% CI: 0.89, 1.06) for O3. Among infected participants, exposure to NO2 and PM2.5 were positively associated with IgG levels for all viral target antigens. Among all participants, 481 (5.0%) had COVID-19 disease. Air pollution levels were associated with COVID-19 disease: adjusted RRs=1.14 (95% CI: 1.00, 1.29) for NO2 and 1.17 (95% CI: 1.03, 1.32) for PM2.5. Exposure to O3 was associated with a slightly decreased risk (RR=0.92; 95% CI: 0.83, 1.03). Associations of air pollution with COVID-19 disease were more pronounced for severe COVID-19, with RRs=1.26 (95% CI: 0.89, 1.79) for NO2 and 1.51 (95% CI: 1.06, 2.16) for PM2.5. DISCUSSION: Exposure to air pollution was associated with a higher risk of COVID-19 disease and level of antibody response among infected but not with SARS-CoV-2 infection. https://doi.org/10.1289/EHP9726.

Heterogeneous associations of polyomaviruses and herpesviruses with allergy-related phenotypes in childhood.

BACKGROUND: Evidence suggests a complex interplay between infections and allergic diseases. OBJECTIVE: To explore the association of 14 common viruses with eczema, asthma, and rhinoconjunctivitis in childhood. METHODS: We used cross-sectional (n = 686) and prospective (n = 440) data from children participating in the Rhea birth cohort. Immunoglobulin G to polyomaviruses (BK polyomavirus, JC polyomavirus, KI polyomavirus [KIPyV], WU polyomavirus [WUPyV], human polyomavirus 6, human polyomavirus 7, Trichodysplasia spinulosa polyomavirus, Merkel cell polyomavirus, human polyomavirus 9, and human polyomavirus 10) and herpesviruses (Epstein-Barr virus, Cytomegalovirus, Herpes simplex virus-1, Herpes simplex virus-2) were measured at age 4 years by fluorescent bead-based multiplex serology. Definitions of eczema, asthma, and rhinoconjunctivitis at ages 4 and 6 years were based on questionnaires. Mediation of the associations by immune biomarkers was tested. RESULTS: Less likely to have eczema at age 4 years were KIPyV-seropositive (odds ratio [OR], 0.47; 95% confidence interval [CI], 0.27-0.82) and human polyomavirus 6 (OR, 0.44; 95% CI, 0.26-0.73) compared with their seronegative counterparts. Seropositivity to Epstein-Barr virus was negatively associated with eczema at age 4 years (OR, 0.39; 95% CI, 0.22-0.67) and 6 years (OR, 0.50; 95% CI, 0.25-0.99). Children with a higher burden of herpesviruses or of skin polyomaviruses had the lowest odds of eczema at age 4 years. Higher odds for asthma at age 4 years were found for WUPyV-seropositive children (OR, 3.98; 95% CI, 1.38-11.51), and for children seropositive to both respiratory polyomaviruses (KIPyV and WUPyV) (OR, 7.35; 95% CI, 1.66-32.59) compared with children seronegative to both. No associations were observed for rhinoconjunctivitis. There was no evidence of mediation by immune biomarkers. CONCLUSION: A heterogeneous pattern of infections and allergic diseases was observed with common infections associated with a decreased eczema risk and an increased asthma risk in children.

Prenatal metal mixtures and child blood pressure in the Rhea mother-child cohort in Greece.

BACKGROUND: Child blood pressure (BP) is predictive of future cardiovascular risk. Prenatal exposure to metals has been associated with higher BP in childhood, but most studies have evaluated elements individually and measured BP at a single time point. We investigated impacts of prenatal metal mixture exposures on longitudinal changes in BP during childhood and elevated BP at 11 years of age. METHODS: The current study included 176 mother-child pairs from the Rhea Study in Heraklion, Greece and focused on eight elements (antimony, arsenic, cadmium, cobalt, lead, magnesium, molybdenum, selenium) measured in maternal urine samples collected during pregnancy (median gestational age at collection: 12 weeks). BP was measured at approximately 4, 6, and 11 years of age. Covariate-adjusted Bayesian Varying Coefficient Kernel Machine Regression and Bayesian Kernel Machine Regression (BKMR) were used to evaluate metal mixture impacts on baseline and longitudinal changes in BP (from ages 4 to 11) and the development of elevated BP at age 11, respectively. BKMR results were compared using static versus percentile-based cutoffs to define elevated BP. RESULTS: Molybdenum and lead were the mixture components most consistently associated with BP. J-shaped relationships were observed between molybdenum and both systolic and diastolic BP at age 4. Similar associations were identified for both molybdenum and lead in relation to elevated BP at age 11. For molybdenum concentrations above the inflection points (~ 40-80 µg/L), positive associations with BP at age 4 were stronger at high levels of lead. Lead was positively associated with BP measures at age 4, but only at high levels of molybdenum. Potential interactions between molybdenum and lead were also identified for BP at age 11, but were sensitive to the cutoffs used to define elevated BP. CONCLUSIONS: Prenatal exposure to high levels of molybdenum and lead, particularly in combination, may contribute to higher BP at age 4. These early effects appear to persist throughout childhood, contributing to elevated BP in adolescence. Future studies are needed to identify the major sources of molybdenum and lead in this population.

Gestational sleep deprivation is associated with higher offspring body mass index and blood pressure.

STUDY OBJECTIVES: The objective of this study was to evaluate the association between gestational sleep deprivation and childhood adiposity and cardiometabolic profile. METHODS: Data were used from two population-based birth cohorts (Rhea study and Amsterdam Born Children and their Development study). A total of 3,608 pregnant women and their children were followed up until the age of 11 years. Gestational sleep deprivation was defined as 6 or fewer hours of sleep per day, reported by questionnaire. The primary outcomes included repeated measures of body mass index (BMI), waist circumference, body fat, serum lipids, systolic and diastolic blood pressure (DBP) levels in childhood. We performed a pooled analysis with adjusted linear mixed effect and Cox proportional hazards models. We tested for mediation by birthweight, gestational age, and gestational diabetes. RESULTS: Gestational sleep deprivation was associated with higher BMI (beta; 95% CI: 0.7; 0.4, 1.0 kg/m2) and waist circumference (beta; 95% CI: 0.9; 0.1, 1.6 cm) in childhood, and increased risk for overweight or obesity (HR; 95% CI: 1.4; 1.1, 2.0). Gestational sleep deprivation was also associated with higher offspring DBP (beta; 95% CI: 1.6; 0.5, 2.7 mmHg). The observed associations were modified by sex (all p-values for interaction < 0.05); and were more pronounced in girls. Gestational diabetes and shorter gestational age partly mediated the seen associations. CONCLUSIONS: This is the first study showing that gestational sleep deprivation may increase offspring's adiposity and blood pressure, while exploring possible mechanisms. Attention to glucose metabolism and preterm birth might be extra warranted in mothers with gestational sleep deprivation.

Early-Life Environmental Exposures and Blood Pressure in Children.

BACKGROUND: Growing evidence exists about the fetal and environmental origins of hypertension, but mainly limited to single-exposure studies. The exposome has been proposed as a more holistic approach by studying many exposures simultaneously. OBJECTIVES: This study aims to evaluate the association between a wide range of prenatal and postnatal exposures and blood pressure (BP) in children. METHODS: Systolic and diastolic BP were measured among 1,277 children from the European HELIX (Human Early-Life Exposome) cohort aged 6 to 11 years. Prenatal (n = 89) and postnatal (n = 128) exposures include air pollution, built environment, meteorology, natural spaces, traffic, noise, chemicals, and lifestyles. Two methods adjusted for confounders were applied: an exposome-wide association study considering the exposures independently, and the deletion-substitution-addition algorithm considering all the exposures simultaneously. RESULTS: Decreases in systolic BP were observed with facility density (ß change for an interquartile-range increase in exposure: -1.7 mm Hg [95% confidence interval (CI): -2.5 to -0.8 mm Hg]), maternal concentrations of polychlorinated biphenyl 118 (-1.4 mm Hg [95% CI: -2.6 to -0.2 mm Hg]) and child concentrations of dichlorodiphenyldichloroethylene (DDE: -1.6 mm Hg [95% CI: -2.4 to -0.7 mm Hg]), hexachlorobenzene (-1.5 mm Hg [95% CI: -2.4 to -0.6 mm Hg]), and mono-benzyl phthalate (-0.7 mm Hg [95% CI: -1.3 to -0.1 mm Hg]), whereas increases in systolic BP were observed with outdoor temperature during pregnancy (1.6 mm Hg [95% CI: 0.2 to 2.9 mm Hg]), high fish intake during pregnancy (2.0 mm Hg [95% CI: 0.4 to 3.5 mm Hg]), maternal cotinine concentrations (1.2 mm Hg [95% CI: -0.3 to 2.8 mm Hg]), and child perfluorooctanoate concentrations (0.9 mm Hg [95% CI: 0.1 to 1.6 mm Hg]). Decreases in diastolic BP were observed with outdoor temperature at examination (-1.4 mm Hg [95% CI: -2.3 to -0.5 mm Hg]) and child DDE concentrations (-1.1 mm Hg [95% CI: -1.9 to -0.3 mm Hg]), whereas increases in diastolic BP were observed with maternal bisphenol-A concentrations (0.7 mm Hg [95% CI: 0.1 to 1.4 mm Hg]), high fish intake during pregnancy (1.2 mm Hg [95% CI: -0.2 to 2.7 mm Hg]), and child copper concentrations (0.9 mm Hg [95% CI: 0.3 to 1.6 mm Hg]). CONCLUSIONS: This study suggests that early-life exposure to several chemicals, as well as built environment and meteorological factors, may affect BP in children.

Polyunsaturated fatty acid status at birth, childhood growth, and cardiometabolic risk: a pooled analysis of the MEFAB and RHEA cohorts.

BACKGROUND/OBJECTIVES: Polyunsaturated fatty acid (PUFA) status during pregnancy has been suggested to influence offspring obesity and cardiometabolic health. We assessed whether prenatal PUFA exposure is associated with rapid infant growth, childhood BMI, and cardiometabolic profile. SUBJECTS/METHODS: In the Dutch MEFAB (n = 266) and Greek RHEA (n = 263) cohorts, we measured n-3 and n-6 PUFA concentrations in cord blood phospholipids, which reflect fetal exposure in late pregnancy. We defined rapid infant growth from birth to 6 months of age as an increase in weight z-score >0.67. We analyzed body mass index (BMI) as continuous and in categories of overweight/obesity at 4 and 6 years. We computed a cardiometabolic risk score at 6-7 years as the sum of waist circumference, non-high-density lipoprotein cholesterol and blood pressure z-scores. Associations of PUFAs with child health outcomes were assessed using generalized linear models for binary outcomes and linear regression models for continuous ones after adjusting for important covariates, and for the pooled estimates, a cohort indicator. RESULTS: In pooled analyses, we found no association of PUFA levels with rapid infant growth, childhood BMI (ß per SD increase in the total n-3:n-6 PUFA ratio = -0.04 SD; 99% CI: -0.15, 0.06; P = 0.65 at 4 years, and -0.05 SD; 99% CI: -0.18, 0.08; P = 0.78 at 6 years), and overweight/obesity. We also found no associations for clustered cardiometabolic risk and its individual components. The results were similar across cohorts. CONCLUSIONS: Our findings suggest that PUFA concentrations at birth are not associated with later obesity development and cardiometabolic risk in childhood.

Human Early Life Exposome (HELIX) study: a European population-based exposome cohort.

PURPOSE: Essential to exposome research is the collection of data on many environmental exposures from different domains in the same subjects. The aim of the Human Early Life Exposome (HELIX) study was to measure and describe multiple environmental exposures during early life (pregnancy and childhood) in a prospective cohort and associate these exposures with molecular omics signatures and child health outcomes. Here, we describe recruitment, measurements available and baseline data of the HELIX study populations. PARTICIPANTS: The HELIX study represents a collaborative project across six established and ongoing longitudinal population-based birth cohort studies in six European countries (France, Greece, Lithuania, Norway, Spain and the UK). HELIX used a multilevel study design with the entire study population totalling 31 472 mother-child pairs, recruited during pregnancy, in the six existing cohorts (first level); a subcohort of 1301 mother-child pairs where biomarkers, omics signatures and child health outcomes were measured at age 6-11 years (second level) and repeat-sampling panel studies with around 150 children and 150 pregnant women aimed at collecting personal exposure data (third level). FINDINGS TO DATE: Cohort data include urban environment, hazardous substances and lifestyle-related exposures for women during pregnancy and their offspring from birth until 6-11 years. Common, standardised protocols were used to collect biological samples, measure exposure biomarkers and omics signatures and assess child health across the six cohorts. Baseline data of the cohort show substantial variation in health outcomes and determinants between the six countries, for example, in family affluence levels, tobacco smoking, physical activity, dietary habits and prevalence of childhood obesity, asthma, allergies and attention deficit hyperactivity disorder. FUTURE PLANS: HELIX study results will inform on the early life exposome and its association with molecular omics signatures and child health outcomes. Cohort data are accessible for future research involving researchers external to the project.

Is early life exposure to polyomaviruses and herpesviruses associated with obesity indices and metabolic traits in childhood?

BACKGROUND: Evidence for an infectious origin of obesity is emerging. We explored whether common viruses were associated with obesity and metabolic traits. METHODS: We used cross-sectional (n = 674) and prospective (n = 440) data from children participating at the 4 and 6 years of age follow-up in the Rhea birth cohort. Presence of IgG antibodies to ten polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, HPyV6, HPyV7, TSPyV, MCPyV, HPyV9, and HPyV10) and four herpesviruses (EBV, CMV, HSV-1, and HSV-2) were measured at age 4. Body mass index, waist circumference, and skinfold thickness were measured at age 4 and 6. Data on serum lipids, leptin, and adiponectin were also available. Multivariable linear regression models were used to explore the associations. RESULTS: At 4 years of age, seroprevalence to polyomaviruses ranged from 21.0% for HPyV9 to 82.0% for HPyV10. Seroprevalence for EBV, CMV, HSV-1, and HSV-2 was 53.0%, 26.0%, 3.6%, and 1.5% respectively. BKPyV seropositivity was associated with lower BMI SD score at age 4 [-0.21 (95% CI: -0.39, -0.03)] and 6 [-0.27 (95% CI:-0.48, -0.05)], waist circumference at age 4 [-1.12 cm (95% CI: -2.10, -0.15)] and 6 [-1.73 cm (95% CI: -3.33, -0.12)], sum of four skinfolds [-2.97 mm (95% CI: -5.70, -0.24)], and leptin levels at age 4 [ratio of geometric means, 0.83 (95% CI: 0.70, 0.98)]. CMV seropositivity was associated with higher BMI SD score at age 4 [0.28 (95% CI: 0.11, 0.45)] and 6 [0.24 (95% CI: 0.03, 0.45)] and sum of four skinfolds at age 6 [4.75 mm (95% CI: 0.67, 8.83)]. Having "2-3 herpesviruses infections" (versus "0 herpesvirus infections") was associated with higher BMI SD score [0.32, (95% CI: 0.12, 0.53)], waist circumference [1.22 cm (95% CI: 0.13, 2.31)], and sum of four skinfolds [3.26 mm (95% CI: 0.18, 6.35)] at age 4. Polyomaviruses burden was not associated with outcomes. CONCLUSIONS: A higher herpesviruses burden and CMV seropositivity were associated with obesity traits in childhood.

Helicobacter pylori Seropositivity and Childhood Neurodevelopment, the Rhea Birth Cohort in Crete, Greece.

BACKGROUND: Limited evidence exists on the association between exposure to Helicobacter pylori infection early in life, including fetal life, and neurodevelopment in childhood. METHODS: We used prospective data on 352 mother-child pairs and cross-sectional data on 674 children to assess the association of maternal and child's H. pylori seropositivity correspondingly on child's neurodevelopment at age four in the Rhea birth cohort in Crete, Greece. Blood levels of immunoglobulin G antibodies to 12 H. pylori proteins were measured using multiplex serology. Child's neurodevelopment at age four was assessed using the McCarthy Scales of Children's Abilities. Linear regression models were used to explore the associations after adjusting for potential confounders. RESULTS: Helicobacter pylori seroprevalence (95% CI) in cord blood, representing maternal status, was 41.5% (36.3%, 46.8%) and in 4 years old children was 6.5% (95% CI 4.8%, 8.7%). Children of H. pylori seropositive mothers had lower score in the general cognitive (-3.87, 95% CI -7.02, -0.72), verbal (-2.96, 95% CI -6.08, 0.15), perceptual performance (-3.37, 95% CI -6.60, -0.15), quantitative (-2.85, 95% CI -6.28, 0.58), and memory scale (-3.37, 95% CI -6.67, -0.07) compared to those of seronegative mothers. Seropositivity in cord blood specifically to GroEl and NapA - two of the 12 H. pylori proteins investigated - was associated with lower scores in almost all scales. At age four, H. pylori seropositive children performed worst in neurodevelopment assessment compared to their seronegative counterparts although no association reached statistically significant level. CONCLUSIONS: Helicobacter pylori infection in early life may be an important but preventable risk factor for poor neurodevelopment.

Common infections with polyomaviruses and herpesviruses and neuropsychological development at 4 years of age, the Rhea birth cohort in Crete, Greece.

BACKGROUND: Viral infections of the central nervous system may have detrimental effects for the developing brain, but the effects of less virulent common infections are unclear. We aim to investigate the impact of common viral infections of early childhood on neuropsychological performance of children at age four. METHODS: We used cross-sectional data on 674 children participating at the 4 years of age follow-up of the Rhea birth cohort in Crete, Greece. Blood levels of IgG antibodies to 10 polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, HPyV6, HPyV7, TSPyV, MCPyV, HPyV9, and HPyV10) and four herpesviruses [Epstein-Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus-1 (HSV-1), and herpes simplex virus-2 (HSV-2)] were measured using multiplex serology. Child's neuropsychological development at age four was assessed using the McCarthy Scales of Children's Abilities, the Attention-Deficit Hyperactivity Disorder Test (ADHDT), and the Strengths and Difficulties Questionnaire (SDQ). Multiple linear regression models were used to explore the associations. RESULTS: Seroprevalence to polyomaviruses ranged from 21% for HPyV9 to 82% for HPyV10. Seroprevalence for EBV was 53%, for CMV 26%, for HSV-1 3.6%, and for HSV-2 1.5%. Children seropositive to ≥8 polyomaviruses had lower score in ADHDT inattention subscale [ß = -1.28 (95% CI: -2.56, -0.001)] and lower score in SDQ hyperactivity-inattention subscale [ß = -.99 (95% CI: -1.60, -0.37)] versus children seropositive to ≤3 polyomaviruses. Seropositivity to BKPyV, a potential neurotropic virus, was associated with higher score in ADHDT inattention subscale [ß = .87 (95% CI: 0.03, 1.71)]. CONCLUSIONS: These findings suggest that acquisition of polyomaviruses during development may influence behavioral outcomes in early childhood.

The Natural History of Human Polyomaviruses and Herpesviruses in Early Life--The Rhea Birth Cohort in Greece.

Sparse data exist on the patterns and determinants of acquisition of polyomaviruses and herpesviruses in childhood. We measured immunoglobulin G seroreactivity against 10 polyomaviruses (BKPyV, JCPyV, KIPyV, WUPyV, MCPyV, HPyV6, HPyV7, TSPyV, HPyV9, HPyV10) and 5 herpesviruses (Epstein Barr virus (EBV), cytomegalovirus (CMV), herpes simplex virus types 1 and 2, human herpesvirus 8) using multiplex serology on blood samples collected at birth (cord blood, n = 626) and at follow-up at 3 years (n = 81) and 4 years (n = 690) of age among the Rhea birth cohort recruited in Greece from pregnant women in 2007-2008. We used Poisson regression with robust variance to identify determinants of seropositivity at age 4. Seroprevalence of polyomaviruses ranged from 38.5% to 99.8% in cord blood and from 20.9% to 82.3% at age 4. Seroprevalence of EBV, CMV, herpes simplex virus types 1 and 2, and human herpesvirus 8 was 99.4%, 74.9%, 26.2%, 8.0%, and 1.6% in cord blood and 52.5%, 25.8%, 3.6%, 1.4%, and 0% at age 4, respectively. Determinants of seropositivity at age 4 were cord seropositivity (JCPyV, HPyV7, HPyV10, CMV), vaginal delivery (HPyV10), breastfeeding (CMV), younger age at day-care entry (BKPyV, KIPyV, WUPyV, TSPyV, HPyV10, HPyV9, EBV, CMV), and swimming pool attendance (BKPyV, KIPyV, WUPyV, HPyV10). Television viewing, parental stress, and hygiene practices were inversely associated with the seroprevalence of polyomaviruses and herpesviruses.

Association of early life exposure to bisphenol A with obesity and cardiometabolic traits in childhood.

BACKGROUND: Bisphenol A (BPA) is a chemical used extensively worldwide in the manufacture of plastic polymers. The environmental obesogen hypothesis suggests that early life exposure to endocrine disrupting chemicals such as BPA may increase the risk for wt gain later in childhood but few prospective epidemiological studies have investigated this relationship. OBJECTIVES: We examined the association of early life BPA exposure with offspring obesity and cardiometabolic risk factors in 500 mother-child pairs from the RHEA pregnancy cohort in Crete, Greece. METHODS: BPA concentrations were measured in spot urine samples collected at the 1st trimester of pregnancy) and from children at 2.5 and 4 years of age. We measured birth wt, body mass index (BMI) from 6 months to 4 years of age, waist circumference, skinfold thickness, blood pressure, serum lipids, C-reactive protein, and adipokines at 4 years of age. BMI growth trajectories from birth to 4 years were estimated by mixed effects models with fractional polynomials of age. Adjusted associations were obtained via multivariable regression analyses. RESULTS: The prevalence of overweight/obesity was 9% at 2, 13% at 3% and 17% at 4 years of age. Geometric mean BPA concentrations were 1.2µg/g creatinine±7.9 in 1st trimester, 5.1µg/g±13.3 in 2.5 years and 1.9µg/g±4.9 in 4 years. After confounder adjustment, each 10-fold increase in BPA at 4 years was associated with a higher BMI z-score (adj. ß=0.2; 95% CI: 0.01, 0.4), waist circumference (adj. ß=1.2; 95% CI: 0.1, 2.2) and sum of skinfold thickness (adj. ß=3.7mm; 95% CI: 0.7, 6.7) at 4 years. Prenatal BPA was negatively associated with BMI and adiposity measures in girls and positively in boys. We found no associations of early life exposure to BPA with other offspring cardiometabolic risk factors. CONCLUSIONS: Prenatal BPA exposure was not consistently associated with offspring growth and adiposity measures but higher early childhood BPA was associated with excess child adiposity.

Association of Prenatal Exposure to Persistent Organic Pollutants with Obesity and Cardiometabolic Traits in Early Childhood: The Rhea Mother-Child Cohort (Crete, Greece).

BACKGROUND: Prenatal exposure to endocrine-disrupting chemicals such as persistent organic pollutants (POPs) may increase risk of obesity later in life. OBJECTIVE: We examined the relation of in utero POPs exposure to offspring obesity and cardiometabolic risk factors at 4 years of age in the Rhea mother-child cohort in Crete, Greece (n = 689). METHODS: We determined concentrations of polychlorinated biphenyls (PCBs), dichlorodiphenyldichloroethylene (DDE), and hexachlorobenzene (HCB) in first-trimester maternal serum. We measured child weight, height, waist circumference, skinfold thicknesses, blood pressure (BP), blood levels of lipids, C-reactive protein, and adipokines at 4 years of age. Childhood obesity was defined using age- and sex-specific cut points for body mass index (BMI) as recommended by the International Obesity Task Force. RESULTS: On multivariable regression analyses, a 10-fold increase in HCB was associated with a higher BMI z-score (adjusted ß = 0.49; 95% CI: 0.12, 0.86), obesity [relative risk (RR) = 8.14; 95% CI: 1.85, 35.81], abdominal obesity (RR = 3.49; 95% CI: 1.08, 11.28), greater sum of skinfold thickness (ß = 7.71 mm; 95% CI: 2.04, 13.39), and higher systolic BP (ß = 4.34 mmHg; 95% CI: 0.63, 8.05) at 4 years of age. Prenatal DDE exposure was associated with higher BMI z-score (ß = 0.27; 95% CI: 0.04, 0.5), abdominal obesity (RR = 3.76; 95% CI: 1.70, 8.30), and higher diastolic BP (ß = 1.79 mmHg; 95% CI: 0.13, 3.46). PCBs were not significantly associated with offspring obesity or cardiometabolic risk factors. CONCLUSIONS: Prenatal exposure to DDE and HCB was associated with excess adiposity and higher blood pressure levels in early childhood.