Maria Melé-Casas

Background: The objective of this study is to analyze the transplacental transmission of SARS-CoV-2 antibodies, their persistence in newborns, the factors that may influence this transmission, and the protection these antibodies confer over time. Methods: This prospective cohort was conducted in a tertiary pediatric hospital in the Barcelona Metropolitan Region, Spain. It included neonates born to mothers who had SARS-CoV-2 infection during pregnancy or delivery between August 2020 and January 2022. We followed the recruited children for at least six months, and blood tests were performed to determine the presence of SARS-CoV-2 antibodies. Results: A total of 101 children were recruited. Among the serologies performed on children under three months of age, 44/82 were positive (53.7%). Newborns whose mothers presented more severe disease exhibited higher seropositivity odds (coefficient 9.747; p = 0.002). There were increased preterm deliveries when maternal infection occurred closer to the time of delivery. No severe SARS-CoV-2 infections were detected in children during the follow-up. Conclusions: Slightly more than half of the SARS-CoV-2 serologies performed in the first three months were positive. This appears to confer protection during early childhood. The severity of maternal infection is the most significant factor influencing the transmission of antibodies in children born to unvaccinated mothers.

Background: Identifying potential factors correlated with the sustained presence of antibodies in plasma may facilitate improved retrospective diagnoses and aid in the appraisal of pertinent vaccination strategies for various demographic groups. The main objective was to describe the persistence of anti-spike IgG one year after diagnosis in children and analyse its levels in relation to epidemiological and clinical variables. Methods: A prospective, longitudinal, observational study was conducted in a university reference hospital in the Metropolitan Region of Barcelona (Spain) (March 2020–May 2021). This study included patients under 18 years of age with SARS-CoV-2 infection (positive PCR or antigen tests for SARS-CoV-2). Clinical and serological follow-up one year after infection was performed. Results: We included 102 patients with a median age of 8.8 years. Anti-spike IgG was positive in 98/102 (96%) 12 months after the infection. There were higher anti-spike IgG levels were noted in patients younger than 2 years (p = 0.034) and those with pneumonia (p < 0.001). A positive and significant correlation was observed between C-reactive protein at diagnosis and anti-spike IgG titre one-year after diagnosis (p = 0.027). Conclusion: Anti-SARS-CoV-2 IgG antibodies were detected in almost all paediatric patients one year after infection. We also observed a positive correlation between virus-specific IgG antibody titres with SARS-CoV-2 clinical phenotype (pneumonia) and age (under 2 years old).

SARS-CoV-2 pneumonia in children has a lower incidence and severity compared to adults. Risk factors are adolescence and comorbidities. Our aims were to describe the characteristics of children admitted with SARS-CoV-2 pneumonia, identify risk factors associated with severity and compare the cases according to the variant of SARS-CoV-2. This was a descriptive and retrospective study, including patients aged 0–18 years hospitalized in a tertiary-care hospital between 1 March 2020 and 1 March 2022. Epidemiological, clinical, diagnostic and therapeutic data were analyzed. Forty-four patients were admitted; twenty-six (59%) were male and twenty-seven (61%) were older than 12 years. Thirty-six (82%) had comorbidities, the most frequent of which were obesity and asthma. Seven (15.9%) patients required high-flow oxygen, eleven (25%) non-invasive ventilation and four (9.1%) conventional mechanical ventilation. In critically ill patients, higher levels of anemia, lymphopenia, procalcitonin, lactate dehydrogenase (LDH) and hypoalbuminemia and lower levels of HDL-cholesterol were detected (all p < 0.05). Prematurity (p = 0.022) was associated with intensive care unit admission. Patients were younger during the Omicron wave (p < 0.01); no variant was associated with greater severity. In conclusion, pediatric patients with a history of prematurity or with anemia, lymphopenia, elevated procalcitonin, elevated LDH levels, hypoalbuminemia and low HDL-cholesterol levels may require admission and present more severe forms. Apart from age, no notable differences between SARS-CoV-2 variant periods were found.

Most studies, aimed at determining the incidence and transmission of SARS-CoV-2 in children and teenagers, have been developed in school settings. Our study conducted surveillance and inferred attack rates focusing on the practice of sports. Prospective and observational study of those attending the sports facilities of Fútbol Club Barcelona (FCB), in Barcelona, Spain, throughout the 2020–2021 season. Participants were young players (from five different sports) and adult workers, who belonged to stable teams (shared routines and were involved in same quarantine rules). Biweekly health questionnaires and SARS-CoV-2 screening were conducted. From the 234 participants included, 70 (30%) both lived and trained in the FCB facilities (Recruitment Pathway 1;RP1) and 164 (70%) lived at their own household and just came to the facilities to train (RP2). During the study, 38 positive cases were identified; none had severe symptoms or needed hospitalization. The overall weekly incidence in the cohorts did not differ compared to the one expected in the community, except for 2 weeks when an outbreak occurred. The attack rate (AR) was three times higher for the participants from RP1, in comparison to those from RP2 (p < 0.01). A Basketball team showed a significant higher AR.  Conclusion: Physical activities in stable teams are not related to an increased risk of transmission of SARS-CoV-2, since there were the same observed cases than expected in the community. The risk is higher in indoor sports (Basketball vs. Football), and in closed cohort living settings (RP1 vs. RP2). The fulfilment of preventive measures is essential. What is Known:• Despite the low numerical impact caused in paediatric hospitalizations during COVID-19 pandemic, the social impact has been maximum.• The transmission potential in children and teenagers is limited, and it had been widely demonstrated in school settings. What is New:• Group physical activities in children and teenagers are not also related to an increased risk of transmission of SARS-CoV-2, when preventive measures, such as washing hands, and screening protocols are applied.• Routine and semi-professional sports activities seem safe environments to promote during this pandemic.

Background: Family clusters offer a good opportunity to study viral transmission in a stable setting. We aimed to analyze the specific role of children in transmission of SARS-CoV-2 within households. Methods: A prospective, longitudinal, observational study, including children with documented acute SARS-CoV-2 infection attending 22 summer-schools in Barcelona, Spain, was performed. Moreover, other patients and families coming from other school-like environments that voluntarily accessed the study were also studied. A longitudinal follow-up (5 weeks) of the family clusters was conducted to determine whether the children considered to be primary cases were able to transmit the virus to other family members. The household reproduction number (Re*) and the secondary attack rate (SAR) were calculated. Results: 1905 children from the summer schools were screened for SARS-CoV-2 infection and 22 (1.15%) tested positive. Moreover, 32 additional children accessed the study voluntarily. Of these, 37 children and their 26 households were studied completely. In half of the cases (13/26), the primary case was considered to be a child and secondary transmission to other members of the household was observed in 3/13, with a SAR of 14.2% and a Re* of 0.46. Conversely, the SAR of adult primary cases was 72.2% including the kids that gave rise to the contact tracing study, and 61.5% without them, and the estimated Re* was 2.6. In 4/13 of the paediatric primary cases (30.0%), nasopharyngeal PCR was persistently positive > 1 week after diagnosis, and 3/4 of these children infected another family member (p<0.01). Conclusions: Children may not be the main drivers of the infection in household transmission clusters in the study population. A prolonged positive PCR could be associated with higher transmissibility.

The results of several clinical trials suggest that continuous positive airway pressure (CPAP) for acute bronchiolitis can be more effective than high-flow nasal cannula (HFNC). The use of HFNC involved a minimum reduction (5%) in admissions to the pediatric intensive care unit (PICU) in our hospital. Our main aim was to evaluate its safety and effectiveness as respiratory support for patients with bronchiolitis in a pediatric general ward. A secondary goal was to compare the admissions to PICU and the invasive mechanical ventilation (IMV) rate of patients treated with HFNC and those treated with HFNC/b-CPAP during the 2018–2019 and 2019–2020 epidemic seasons, respectively. Two prospective single-centre observational studies were performed. For the main aim, a cohort study (CS1) was carried out from 1st of November 2019 to 15th of January 2020. Inclusion criteria were children aged up to 3 months with bronchiolitis treated with b-CPAP support when HFNC failed. Epidemiological and clinical parameters were collected before and 60 min after the onset of CPAP and compared between the responder (R) and non-responders (NR) groups. NR was the group that required PICU admission. One hundred fifty-eight patients were admitted to the ward with bronchiolitis and HFNC. Fifty-seven out of one hundred fifty-eight required b-CPAP. No adverse events were observed. Thirty-two out of fifty-seven remained in the general ward (R-group), and 25/57 were admitted to PICU (NR-group). There were statistically significant differences in respiratory rate (RR) and heart rate (HR) between both groups before and after the initiation of b-CPAP, but the multivariable models showed that the main differences were observed after 60 min of therapy (lower HR, RR, BROSJOD score and FiO2 in the R-group). For the secondary aim, another cohort study (CS2) was performed comparing data from a pre-b-CPAP bronchiolitis season (1st of November 2018 to 15th January 2019) and the b-CPAP season (2019–2020). Inclusion criteria in pre-b-CPAP season were children aged up to 3 months admitted to the same general ward with moderate-severe bronchiolitis and with HFNC support. Admissions to PICU during the CPAP season were significantly reduced, without entailing an increase in the rate of IMV.Conclusion: The implementation of b-CPAP for patients with bronchiolitis in a pediatric ward, in whom HFNC fails, is safe and effective and results in a reduction in PICU admissions. What is Known:• Bronchiolitis is one of the most frequent respiratory infections in children and one of the leading causes of hospitalization in infants.• Several studies suggest that the use of continuous positive airway pressure (CPAP) for acute bronchiolitis can be more effective than the high flow nasal cannula (HFNC). CPAP is a non-invasive ventilation (NIV) therapy used in patients admitted to pediatric intensive care unit (PICU) with progressive moderate-severe bronchiolitis.There is little experience in the literature on the use of continuous positive airway pressure (CPAP) for acute bronchiolitis in a general ward. What is New:• CPAP could be safely and effectively used as respiratory support in young infants with moderate-severe bronchiolitis in a general ward and it reduced the rate of patients who required PICU admission.• Patients' heart and respiratory rate and their FiO2 needs in the first 60 minutes may help to decide whether or not to continue the CPAP therapy in a general ward.

The increased incidence of COVID-19 cases and deaths in Spain in March 2020 led to the declaration by the Spanish government of a state of emergency imposing strict confinement measures on the population. The objective of this study was to characterize the nasopharyngeal microbiota of children and adults and its relation to SARS-CoV-2 infection and COVID-19 severity during the pandemic lockdown in Spain. This cross-sectional study included family households located in metropolitan Barcelona, Spain, with one adult with a previous confirmed COVID-19 episode and one or more exposed co-habiting child contacts. Nasopharyngeal swabs were used to determine SARS-CoV-2 infection status, characterize the nasopharyngeal microbiota and determine common respiratory DNA/RNA viral co-infections. A total of 173 adult cases and 470 exposed children were included. Overall, a predominance of Corynebacterium and Dolosigranulum and a limited abundance of common pathobionts including Haemophilus and Streptococcus were found both among adults and children. Children with current SARS-CoV-2 infection presented higher bacterial richness and increased Fusobacterium, Streptococcus and Prevotella abundance than non-infected children. Among adults, persistent SARS-CoV-2 RNA was associated with an increased abundance of an unclassified member of the Actinomycetales order. COVID-19 severity was associated with increased Staphylococcus and reduced Dolosigranulum abundance. The stringent COVID-19 lockdown in Spain had a significant impact on the nasopharyngeal microbiota of children, reflected in the limited abundance of common respiratory pathobionts and the predominance of Corynebacterium, regardless of SARS-CoV-2 detection. COVID-19 severity in adults was associated with decreased nasopharynx levels of healthy commensal bacteria.

Surveillance tools to estimate infection rates in young populations are essential to guide recommendations for school reopening and management during viral epidemics. Ideally, field-deployable non-invasive, sensitive techniques are required to detect low viral load exposures among asymptomatic children. We determined SARS-CoV-2 antibody conversion by high-throughput Luminex assays in saliva samples collected weekly in 1,509 children and 396 adults in 22 Summer schools and 2 pre-schools in 27 venues in Barcelona, Spain, from June 29 ^th to July 31 ^st 2020, between the first and second COVID-19 pandemic waves. Saliva antibody conversion defined as ≥4-fold increase in IgM, IgA and/or IgG levels to SARS-CoV-2 antigens between two visits over a 5-week period was 3.22% (49/1518), or 2.36% if accounting for potentially cross-reactive antibodies, six times higher than the cumulative infection rate (0.53%) by weekly saliva RT-PCR screening. IgG conversion was higher in adults (2.94%, 11/374) than children (1.31%, 15/1144) (p=0.035), IgG and IgA levels moderately increased with age, and antibodies were higher in females. Most antibody converters increased both IgG and IgA antibodies but some augmented either IgG or IgA, with a faster decay over time for IgA than IgG. Nucleocapsid rather than spike was the main antigen target. Anti-spike antibodies were significantly higher in individuals not reporting symptoms than symptomatic individuals, suggesting a protective role against COVID-19. To conclude, saliva antibody profiling including three isotypes and multiplexing antigens is a useful and more user-friendly tool for screening pediatric populations to determine SARS-CoV-2 exposure and guide public health policies during pandemics.

Objective Three scores have been proposed to stratify the risk of mortality for each cardiac surgical procedure: The RACHS-1, the Aristotle Basic Complexity (ABC), and the STS-EACTS complexity scoring model. The aim was to compare the ability to predict mortality and morbidity of the three scores applied to a specific population. Design Retrospective, descriptive study. Setting Pediatric and neonatal intensive care units in a referral hospital. Patients Children under 18 years admitted to the intensive care unit after surgery. Interventions None. Outcome measures Demographic, clinical, and surgical data were assessed. Morbidity was considered as prolonged length of stay (LOS > 75 percentile), high respiratory (>72 hours of mechanical ventilation), and high hemodynamic support (inotropic support >20). Results One thousand and thirty-seven patients were included, in which 205 were newborns (18%). The category 2 was the most frequent in the three scores: In RACHS-1, ABC, 44.9%, and STS-EACTS, 40.8%. Newborns presented significant higher categories. Children required cardiopulmonary bypass in more occasions (P < .001) but the times of bypass and aortic cross-clamp were significantly higher in newborns (P < .001 and P = .016). Thirty-two patients died (2.8%). A quarter of patients had a prolonged LOS, 17%, a high respiratory support, and 7.1%, a high hemodynamic support. RACHS-1 (AUC 0.760) and STS-EACTS (AUC 0.763) were more powerful for predicting mortality and STS-EACTS for predicting prolonged LOS (AUC 0.733) and the need for high respiratory support (AUC 0.742). Conclusions STS-EACTS seems to stratify better risk of mortality, prolonged LOS, and need for respiratory support after surgery.

The mechanisms by which inflammation affects the different emotional moods are only partially known. Previous works have pointed to stress hormones like glucocorticoids plus the vascular factor endothelin-1 as key factors evoking stressful states especially in relation to endothelial dysfunctions. With this work, it was our intention to establish the role of pro- and anti-inflammatory cytokine expression variations towards depression-like behaviors and consequently the development of neurodegeneration events caused by endothelial damages in the hamster (Mesocricetus auratus). Such a rodent, which is considered a valuable animal model to test depression and anxiety states, exhibited a variety of depression-like behaviors including reduction in sucrose consumption, locomotion, and exploration (p < 0.01) following exposure to unpredictable chronic mild stress. Contextually, a tight correlation between unpredictable chronic mild stress-induced depressive states and expression of the pro-inflammatory cytokines was detected as shown by marked expression levels (p < 0.01) of IL-1β and NF-kB in the hippocampus, amygdala, and prefrontal cortex. Even the anti-inflammatory cytokine IL-10 supplied notably significant (p < 0.001) expression levels in the same areas of resilient hamsters. Application of hemodynamic and endothelial functional studies pointed to altered arterial endothelial activities in depressed with respect to resilient animals. Moreover, evident damaged neuronal fields in the above areas of depressed hamsters allowed us to correlate such a behavioral phenomenon to the upregulation of IL-1β and NF-κB. Overall, the differing roles of pro- and anti-inflammatory cytokines on depressive states, especially in view of brain endothelial damages, may provide novel therapeutic measures against mood disorders linked to neurodegenerative diseases.