Physical Fitness and Body Mass Index Status of Hong Kong Primary Schoolchildren across the COVID-19 Pandemic, before and after School Closure.

OBJECTIVE: To determine whether health-related physical fitness and body mass index (BMI) status differed before and after school closure from the COVID-19 pandemic in a population-based cohort of Hong Kong primary schoolchildren. STUDY DESIGN: We examined the BMI z score, BMI status, and physical fitness z scores including (i) upper limb muscle strength, (ii) 1-minute sit-up test, (iii) sit-and-reach test, and (iv) endurance run tests, among 3 epochs: prepandemic (September 2018-August 2019), before school closure (September 2019-January 2020), and partial school reopening (September 2021-August 2022), using a repeated cross-sectional approach. RESULTS: A total of 137 752 primary schoolchildren aged 6-12 years were recruited over 3 academic years. Obesity increased significantly from 25.9% in 2018/19 to 31.0% in 2021/22, while underweight increased slightly from 6.1% to 6.5%. All tested parameters were adversely affected by the pandemic. The negative trend over time was far more pronounced in all 4 physical fitness scores in the underweight group, although performance in handgrip strength had no significance between 2018/19 and 2021/22. CONCLUSIONS: Schoolchildren who are both underweight and overweight/obese are vulnerable to adverse changes in physical fitness during the COVID-19 pandemic. To eliminate the negative health and fitness outcomes, it is urgent to develop strategies for assisting schoolchildren in achieving a healthy weight, especially in the postpandemic era.

Vulnerability and resilience in children during the COVID-19 pandemic.

BACKGROUND: The coronavirus disease 2019 (COVID-19) pandemic is having a profound impact on the health and development of children worldwide. There is limited evidence on the impact of COVID-19 and its related school closures and disease-containment measures on the psychosocial wellbeing of children; little research has been done on the characteristics of vulnerable groups and factors that promote resilience. METHODS: We conducted a large-scale cross-sectional population study of Hong Kong families with children aged 2-12 years. Parents completed an online survey on family demographics, child psychosocial wellbeing, functioning and lifestyle habits, parent-child interactions, and parental stress during school closures due to COVID-19. We used simple and multiple linear regression analyses to explore factors associated with child psychosocial problems and parental stress during the pandemic. RESULTS: The study included 29,202 individual families; of which 12,163 had children aged 2-5 years and 17,029 had children aged 6-12 years. The risk of child psychosocial problems was higher in children with special educational needs, and/or acute or chronic disease, mothers with mental illness, single-parent families, and low-income families. Delayed bedtime and/or inadequate sleep or exercise duration, extended use of electronic devices were associated with significantly higher parental stress and more psychosocial problems among pre-schoolers. CONCLUSIONS: This study identifies vulnerable groups of children and highlights the importance of strengthening family coherence, adequate sleep and exercise, and responsible use of electronic devices in promoting psychosocial wellbeing during the COVID-19 pandemic.

Examining family pre-pandemic influences on adolescent psychosocial wellbeing during the COVID-19 pandemic.

During the COVID-19 lockdown, with social distancing measures in place and a decrease in social activities, emotional states are more likely to be transferred between family members via increased interactions and communication. However, longitudinal evidence, particularly for early adolescents, is lacking. This study investigated family pre-pandemic influences on parental stress and adolescent psychosocial wellbeing during the COVID-19 pandemic. Data were collected from 233 adolescents and their parents before and during the initial phase of the pandemic. Parents reported their own stress level and perception of adolescent adjustment problems, whereas adolescents reported their own psychological distress level. In addition, adolescents also reported their satisfaction with family life in the pre-pandemic survey. Cross-lagged path models indicated reciprocal associations between parental stress and perception of adolescent adjustment problems. Compared to adolescents low in pre-pandemic family life satisfaction, those adolescents with higher levels of family life satisfaction before the pandemic reported lower levels of anxiety and stress only when parental stress showed no increase during the pandemic. Findings provide support for the mutual influences between parental stress and perceived adolescent adjustment problems during the pandemic. Special attention should be paid to those adolescents who undergo significant family life changes during the pandemic.

Comorbidity of ADHD and allergic diseases in early adolescence: The role of parental smoking at home.

A growing body of research suggests an association between attention deficit hyperactivity disorder (ADHD) and allergic disorders, but little work has been done to explore the role of external factors such as parental smoking at home in the development of comorbid ADHD and allergic disorders. This study aimed to examine the association between allergic diseases and ADHD adjusted for exposure to parental smoking at home in early adolescents. We recruited 250 male (41.7%) and 350 female (58.3%) adolescents (mean [SD] age, 13.29 [0.52] years) via chain-referral sampling. Their ADHD symptoms were assessed by the parent proxy-report version of the Chinese Strengths and Weaknesses of Attention-Deficit/Hyperactivity-symptoms and Normal-behaviours (SWAN) rating scale. Data on the participants' history of clinician-diagnosed allergic diseases, family socio-demographics, and parental smoking habit were collected using a parent-completed questionnaire. Regression analyses were performed to examine the associations of interest. The levels of ADHD symptoms were comparable between allergic and non-allergic participants after controlling for child and family demographics and parental smoking at home. Notably, the risk of probable ADHD was particularly high in participants with food allergies (odd ratio = 4.51, p = 0.011) but not in those with allergic rhinitis after adjusting for parental smoking at home. Our findings suggest that second-hand smoke exposure at home is a potential risk factor underlying the link between ADHD and allergic diseases. Current management guidelines should emphasize the importance of early identification and cessation of tobacco smoke exposure for prevention of comorbidity of ADHD and allergic disorders. Clinical Trial Registration (if any): NA.

Parent Technology Use, Parent-Child Interaction, Child Screen Time, and Child Psychosocial Problems among Disadvantaged Families.

OBJECTIVE: To disentangle the pathways of parent technology use, parent-child interactions, child screen time, and child psychosocial difficulties among disadvantaged families in Hong Kong. STUDY DESIGN: Parents of 1254 3-year-old children from the KeySteps@JC project reported on the number of hours their children used electronic devices every day and evaluated their children's psychosocial behaviors using the Strengths and Difficulties Questionnaire. These parents also reported on their own digital device usage patterns and the frequency of parent-child interactions and provided sociodemographic data. Structural models were tested with parent technology use (independent variable), parent technological distractions and parent-child interactions and child screen time (mediators), child psychosocial problems (dependent variable), and children's age and sex and family socioeconomic status index (confounding variables). RESULTS: Parent distraction with technology during parent-child interactions completely mediated the overall association between parent problematic digital technology use and child screen use duration. Parent problematic digital technology use was positively and directly associated with child psychosocial difficulties. In addition, it was indirectly related to child psychosocial difficulties through technological distractions and reductions in parent-child interactions and increased media use by children. CONCLUSION: Higher parent digital technology usage was associated with reduced parent-child interactions and increased child screen time and psychosocial difficulties in disadvantaged families. These results suggest that limiting parents' use of electronic devices in front of their young children could be beneficial for childhood psychosocial development.

A Comparison Between Chinese Children Infected with Coronavirus Disease-2019 and with Severe Acute Respiratory Syndrome 2003.

OBJECTIVES: To compare the clinical and laboratory features of severe acute respiratory syndrome 2003 (SARS) and coronavirus disease 2019 (COVID-19) in 2 Chinese pediatric cohorts, given that the causative pathogens and are biologically similar. STUDY DESIGN: This is a cross-sectional study reviewing pediatric patients with SARS (n = 43) and COVID-19 (n = 244) who were admitted to the Princess Margaret Hospital in Hong Kong and Wuhan Children's Hospital in Wuhan, respectively. Demographics, hospital length of stay, and clinical and laboratory features were compared. RESULTS: Overall, 97.7% of patients with SARS and 85.2% of patients with COVID-19 had epidemiologic associations with known cases. Significantly more patients with SARS developed fever, chills, myalgia, malaise, coryza, sore throat, sputum production, nausea, headache, and dizziness than patients with COVID-19. No patients with SARS were asymptomatic at the time of admission, whereas 29.1% and 20.9% of patients with COVID-19 were asymptomatic on admission and throughout their hospital stay, respectively. More patients with SARS required oxygen supplementation than patients with COVID-19 (18.6 vs 4.7%; P = .004). Only 1.6% of patients with COVID-19 and 2.3% of patients with SARS required mechanical ventilation. Leukopenia (37.2% vs 18.6%; P = .008), lymphopenia (95.4% vs 32.6%; P < .01), and thrombocytopenia (41.9% vs 3.8%; P < .001) were significantly more common in patients with SARS than in patients with COVID-19. The duration between positive and negative nasopharyngeal aspirate and the length in hospital stay were similar in patients with COVID-19, regardless of whether they were asymptomatic or symptomatic, suggesting a similar duration of viral shedding. CONCLUSIONS: Children with COVID-19 were less symptomatic and had more favorable hematologic findings than children with SARS.

Normative values of motor performance and their relationship with BMI status in Hong Kong preschoolers.

This study aimed to establish sex- and age-specific reference values for motor performance (MP) in Hong Kong preschoolers aged 3-5 years old and examine the relationship between MP and BMI status. A cross-sectional study was conducted among 5579 preschoolers in Hong Kong. Three MP tests were administered, and height and weight information were collected. GAMLSS was used to compute the normative values of the motor tests. Boys outperformed girls in activities requiring muscle strength and power, while girls outperformed boys in activities requiring balance and coordination. The MP scores increased with age for both overarm beanbag throw and standing long jump for both sexes, while the one-leg balance scores showed larger differences between P50 and P95 in older preschoolers. Children with excessive weight performed worse in standing long jump and one-leg balance compared to their healthy weight peers. This study provides valuable information on the MP of preschoolers in Hong Kong, including sex- and age-specific reference values and the association between BMI status and MP scores. These findings can serve as a reference for future studies and clinical practice and highlight the importance of promoting motor skill development in preschoolers, particularly those who are overweight or obese.

Expanded Prader-Willi syndrome due to chromosome 15q11.2-14 deletion: report and a review of literature.

We report on a male infant with de novo unbalanced t(5;15) translocation resulting in a 17.23 Mb deletion within 15q11.2-q14 and a 25.12 kb deletion in 5pter. The 15q11.2-q14 deletion encompassed the 15q11.2-q13 Prader-Willi syndrome (PWS) critical region and the recently described 15q13.3 microdeletion syndrome region while the 5pter deletion contained no RefSeq genes. From our literature review, patients with similar deletions in chromosome 15q exhibit expanded phenotype of severe developmental delay, protracted feeding problem, absent speech, central visual impairment, congenital malformations and epilepsy in addition to those typical of PWS. The patient reported herein had previously unreported anomalies of mega cisterna magna, horseshoe kidney and the rare neonatal interstitial lung disease known as pulmonary interstitial glycogenosis. Precise breakpoint delineation by microarray is useful in patients with atypical PWS deletions to guide investigation and prognostication.

Haploidentical Transplant Achieves Long-Term Remission in Relapsed Refractory Leukemia With Fludarabine-Induced Neurotoxicity Complication.

Hematopoietic stem cell transplant is potentially curative for relapsed/refractory leukemia. However, neurotoxicity is common and has been reported in 11% to 59% of children following hematopoietic stem cell transplant. Most pediatric studies of the neurological effects of hematopoietic stem cell transplant have focused on acute neurotoxicity. Limited information is available for long-term neurotoxicity, particularly those cases that are severe and permanent and caused by conditioning chemotherapy. Here, we report 2 cases of relapsed acute lymphoblastic leukemia that achieved long-term remission by haploidentical hematopoietic stem cell transplant but remained complicated with severe and persistent fludarabine-induced neurotoxicity.

Family Financial Pressure in Childhood and Telomere Length in Early Adolescence: A Prospective Study.

Much research on children in high-risk environments has focused on the biological consequences of maltreatment, adversity, and trauma. Whether other early-life stress sources such as family financial hardship are implicated in the cellular mechanism of disease development remains unclear. This study investigated the long-term effect of childhood exposure to family financial pressure on telomere length. It involved two waves of data collection occurring when participants reached Grade 3 (W1) and 7 (W2), respectively. In W1, parents reported family demographics and perceived financial stressors and pressure. In W2, participants provided buccal swab samples for measurement of their telomere length. Data from 92 participants (Mage in W2 = 13.2 years; 56.5% male) were analyzed. The main type of stressors reported by parents who perceived high family financial pressure in W1 were child-level stressors including affordability of their medical and educational expenses. Participants exposed to high parent-perceived family financial pressure in W1 had shorter telomeres in W2 when compared to those exposed to low parent-perceived family financial pressure (ß = -0.61, p = 0.042). Subgroup analyses revealed stronger associations in girls than boys. These findings reveal an important spillover effect between parental financial perceptions and stress and children's health at the cellular level.

Using Latent Class Analyses to Examine Health Disparities among Young Children in Socially Disadvantaged Families during the COVID-19 Pandemic.

Rising income inequality is strongly linked to health disparities, particularly in regions where uneven distribution of wealth and income has long been a concern. Despite emerging evidence of COVID-19-related health inequalities for adults, limited evidence is available for children and their parents. This study aimed to explore subtypes of families of preschoolers living in the disadvantaged neighborhoods of Hong Kong based on patterns of family hardship and to compare their patterns of parenting behavior, lifestyle practices, and wellbeing during the COVID-19 pandemic. Data were collected from 1338 preschoolers and their parents during March to June 2020. Latent class analysis was performed based on 11 socioeconomic and disease indicators. Multivariate logistic regressions were used to examine associations between identified classes and variables of interest during the COVID-19 pandemic. Four classes of family hardship were identified. Class 1 (45.7%) had the lowest disease and financial burden. Class 2 (14.0%) had the highest financial burden. Class 3 (5.9%) had the highest disease burden. Class 4 (34.5%) had low family income but did not receive government welfare assistance. Class 1 (low hardship) had lower risks of child maltreatment and adjustment problems than Class 2 (poverty) and Class 3 (poor health). However, children in Class 1 (low hardship) had higher odds of suffering psychological aggression and poorer physical wellbeing than those in Class 4 (low income), even after adjusting for child age and gender. The findings emphasize the need to adopt flexible intervention strategies in the time of large disease outbreak to address diverse problems and concerns among socially disadvantaged families.

Digital competence as a protective factor against gaming addiction in children and adolescents: A cross-sectional study in Hong Kong.

Background: Digital competence can help children and adolescents engage with technology for acquiring new knowledge and for broadening social contact and support, while reducing the risk of inappropriate media use. This study investigated the effects of digital competence on the risk of gaming addiction among children and adolescents. We explored whether students with good digital competence were protected from the adverse effects of media use and the risk of gaming addiction. Methods: 1956 students (690 primary and 1266 secondary) completed a digital competence assessment and a self-report questionnaire on their mental health status, use of digital devices, and experiences of cyberbullying. Multiple regression analyses with further mediation and moderation analyses were performed to investigate the association of digital competence with gaming addiction and mental health in children and adolescents. Findings: Regression analyses showed that children and adolescents with better digital competence were less likely to develop gaming addiction (ß = -0.144, p < 0.0001) and experienced less cyberbullying behaviour as perpetrators (ß = -0.169, p < 0.0001) and as victims (ß = -0.121, p < 0.0001). Digital competence was found to mediate the relationship between digital device usage time and gaming addiction. Interpretation: Digital competence is associated with less gaming addiction and could potentially lead to better mental wellbeing by reducing the risks of gaming addiction and cyberbullying. Education that promotes digital competence is essential to maximize the benefits of media use, while reducing the potential adverse effects from the inappropriate use of digital devices. Funding: This study was supported by a grant from the Research Grants Council of the HKSAR Government (#T44-707/16N) under the Theme-based Research Scheme.

Associations between childhood maltreatment and psychiatric disorders: analysis from electronic health records in Hong Kong.

There has been a lack of high-quality evidence concerning the association between childhood maltreatment and psychiatric diagnoses particularly for Axis II disorders. This study aimed to examine the association between childhood maltreatment exposure and Axis I and Axis II psychiatry disorders using electronic health records. In this study, the exposed group (n = 7473) comprised patients aged 0 to 19 years with a first-time record of maltreatment episode between January 1, 2001 and December 31, 2010, whereas the unexposed group (n = 26,834) comprised individuals of the same gender and age who were admitted into the same hospital in the same calendar year and month but had no records of maltreatment in the Hong Kong Clinical Data Analysis and Reporting System (CDARS). Data on their psychiatric diagnoses recorded from the date of admission to January 31, 2019 were extracted. A Cox proportional hazard regression model was fitted to estimate the hazard ratio (HR, plus 95% CIs) between childhood maltreatment exposure and psychiatric diagnoses, adjusting for age at index visit, sex, and government welfare recipient status. Results showed that childhood maltreatment exposure was significantly associated with subsequent diagnosis of conduct disorder/ oppositional defiant disorder (adjusted HR, 10.99 [95% CI 6.36, 19.01]), attention deficit hyperactivity disorder (ADHD) (7.28 [5.49, 9.65]), and personality disorders (5.36 [3.78, 7.59]). The risk of psychiatric disorders following childhood maltreatment did not vary by history of childhood sexual abuse, age at maltreatment exposure, and gender. Individuals with a history of childhood maltreatment are vulnerable to psychiatric disorders. Findings support the provision of integrated care within the primary health care setting to address the long-term medical and psychosocial needs of individuals with a history of childhood maltreatment.

Severity of SARS-CoV-2 Omicron BA.2 infection in unvaccinated hospitalized children: comparison to influenza and parainfluenza infections.

There has been a rapid surge of hospitalization due to the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Omicron variants globally. The severity of Omicron BA.2 in unexposed, unvaccinated, hospitalized children is unknown. We investigated the severity and clinical outcomes of COVID-19 infection during the Omicron wave in uninfected, unvaccinated hospitalized children and in comparison with influenza and parainfluenza viral infections. This population-based study retrieved data from the HK territory-wide CDARS database of hospitalisations in all public hospitals and compared severe outcomes for the Omicron BA.2-dominant fifth wave (5-28 February 2022, n = 1144), and influenza and parainfluenza viruses (1 January 2015-31 December 2019, n = 32212 and n = 16423, respectively) in children 0-11 years old. Two deaths (0.2%) out of 1144 cases during the initial Omicron wave were recorded. Twenty-one (1.8%) required PICU admission, and the relative risk was higher for Omicron than influenza virus (n = 254, 0.8%, adjusted RR = 2.1, 95%CI 1.3-3.3, p = 0.001). The proportion with neurological complications was 15.0% (n = 171) for Omicron, which was higher than influenza and parainfluenza viruses (n = 2707, 8.4%, adjusted RR = 1.6, 95%CI 1.4-1.9 and n = 1258, 7.7%, adjusted RR = 1.9, 95%CI 1.6-2.2, p < 0.001 for both, respectively). Croup occurred for Omicron (n = 61, 5.3%) more than influenza virus (n = 601, 1.9%, adjusted RR = 2.0, 95%CI 1.5-2.6, p < 0.001) but not parainfluenza virus (n = 889, 5.4%). Our findings showed that for hospitalized children who had no past COVID-19 or vaccination, Omicron BA.2 was not mild. Omicron BA.2 appeared to be more neuropathogenic than influenza and parainfluenza viruses. It targeted the upper airways more than influenza virus.

Early-life activities mediate the association between family socioeconomic status in early childhood and physical fitness in early adolescence.

The graded association between family socioeconomic status (SES) and physical fitness is evident, but little is known about the mechanism underlying this association. This study investigated the role of early-life activities as mediators of the longitudinal relationship between early-life SES and health-related physical fitness in 168 adolescents (51.2% boys; final mean age: 12.4 years old). In Wave 1 (2011-12), their parents completed questionnaires about family socioeconomic status (SES), parent-child activities, and child screen time. In Wave 2 (2014-15), participants' physical activity levels were assessed through parent proxy-reports. In Wave 3 (2018-19), a direct assessment of handgrip strength, standing long-jump, and 6-min walk test (6MWT) performance was conducted. After controlling for demographic factors, results of mediation analyses revealed that (a) Wave 1 SES predicted Wave 3 long-jump and 6MWT performance; (b) child physical activity level in Wave 2 mediated the relation between Wave 1 SES and standing long-jump performance in Wave 3; and (c) recreational parent-child activities and child screen time in wave 1 mediated the relation between Wave 1 SES and 6MWT performance in Wave 3. Our findings suggest that the type and frequency of early-life activities play a role in the graded association between childhood SES and physical fitness in adolescence.

Age- and Sex-Specific Physical Fitness Reference and Association with Body Mass Index in Hong Kong Chinese Schoolchildren.

There is lacking a population-based study on the fitness level of Hong Kong schoolchildren, and it seems that increasing childhood obesity prevalence has shifted the classification of healthy fitness, with 'underfit' as normal. This cross-sectional territory study aimed to develop an age- and sex-specific physical fitness reference using a representative sample of children aged 6-17 and to determine the associations with body mass index in schoolchildren. The study analyzed Hong Kong School Physical Fitness Award Scheme data covering grade 1 to grade 12 students' physical fitness and anthropometric measurements from 2017 to 2018. This reference was established without the impact due to COVID-19. Four aspects of physical fitness tests were measured using a standardized protocol, including (i) upper limb muscle strength, (ii) one-minute sit-up, (iii) sit-and-reach, and (iv) endurance run tests. The generalized additive model for location, scale, and shape was used to construct the reference charts. A Mann-Whitney U test was used to compare the mean differences in age, weight, and height, and a Pearson's chi-square test was used to examine the distributions of sex groups. A Kruskal-Wallis test was used to compare the group differences in BMI status, followed by the Dunn test for pairwise comparisons. A 5% level of significance was regarded as statistically significant. Data of 119,693 students before the COVID-19 pandemic were included in the analysis. The association between physical fitness level and BMI status varied depending on the test used, and there were significant differences in fitness test scores among BMI groups. The mean test scores of the obese group were lower in most of the tests for both boys and girls, except for handgrip strength. The underweight group outperformed the obese group in push-ups, one-minute sit-ups, and endurance run tests, but not in handgrip strength. In conclusion, a sex- and age-specific physical fitness reference value for Hong Kong Chinese children aged 6 to 17 years old is established, and this study demonstrated a nonlinear relationship between BMI status and physical fitness. The reference will help to identify children with poor physical fitness to offer support and guidance on exercise training. It also serves as a baseline for assessing the impact of the COVID-19 pandemic on Hong Kong students' physical fitness.

Evidence of individual differences in the long-term social, psychological, and cognitive consequences of child maltreatment.

BACKGROUND: The prevalence and consequences of child maltreatment are alarming, but evidence from studies with long follow-up intervals are limited. This study examined the long-term consequences of child maltreatment in relation to age of onset and follow-up interval. METHODS: The exposed group comprised 63 individuals (aged 13-34 years) with a first-time diagnosis of child maltreatment between 2001 and 2010, whereas the unexposed group comprised 63 individuals who were matched upon gender, age of onset, follow-up period, and poverty status at the index hospital admission but had no medical records of maltreatment in Hong Kong. The participants completed a set of questionnaires on executive functions and mental health and provided blood samples for measurement of IL-6 and IL-10 levels during a health assessment session. RESULTS: Compared with the unexposed group, the exposed group reported poorer maternal care during childhood (ß = -4.64, p < 0.001) and had lower family support (ß = -2.97, p = 0.010) and higher inflammatory responses (IL-6: ß = 0.15, p = 0.001; IL-10: ß = 0.11, p = 0.011) at follow-up. Additionally, the associations of childhood maltreatment exposure with family support and maternal care differed by age of onset and the length of time since exposure. CONCLUSIONS: This matched cohort study highlights childhood maltreatment as a risk factor for systemic inflammation and an indicator of suboptimal social environment, both of which could persist over a long period of time.

Impact of COVID-19 Pandemic on School-Aged Children's Physical Activity, Screen Time, and Sleep in Hong Kong: A Cross-Sectional Repeated Measures Study.

Despite concerns about the negative effects of social distancing and prolonged school closures on children's lifestyle and physical activity (PA) during the COVID-19 pandemic, robust evidence is lacking on the impact of the pandemic-related school closures and social distancing on children's wellbeing and daily life. This study aimed to examine changes in the PA levels, sleep patterns, and screen time of school-aged children during the different phases of the COVID-19 outbreak in Hong Kong using a repeated cross-sectional design. School students (grades 1 to 12) were asked to report their daily electronic device usage and to fill in a sleep diary, recording their daily sleep onset and wake-up time. They were equipped with a PA monitor, Actigraph wGT3X-BT, to obtain objective data on their PA levels and sleep patterns. Students were recruited before the pandemic (September 2019-January 2020; n = 577), during school closures (March 2020-April 2020; n = 146), and after schools partially reopened (October 2020-July 2021; n = 227). Our results indicated lower PA levels, longer sleep duration, and longer screen time among participants recruited during school closures than those recruited before the COVID-19 outbreak. Primary school students were found to sleep on average for an extra hour during school closures. The later sleep onset and increased screen time documented during school closures persisted when schools partially reopened. Our findings illustrate the significant impact of social distancing policies during the COVID-19 pandemic on the sleep pattern, screen time, and PA level in school-aged children in Hong Kong. Professionals should urgently reinforce the importance of improving physically activity, good sleep hygiene, and regulated use of electronic devices for parents and school-aged children during this unprecedented time.

Immunogenicity and reactogenicity of SARS-CoV-2 vaccines BNT162b2 and CoronaVac in healthy adolescents.

We present an interim analysis of a registered clinical study (NCT04800133) to establish immunobridging with various antibody and cellular immunity markers and to compare the immunogenicity and reactogenicity of 2-dose BNT162b2 and CoronaVac in healthy adolescents as primary objectives. One-dose BNT162b2, recommended in some localities for risk reduction of myocarditis, is also assessed. Antibodies and T cell immune responses are non-inferior or similar in adolescents receiving 2 doses of BNT162b2 (BB, N = 116) and CoronaVac (CC, N = 123) versus adults after 2 doses of the same vaccine (BB, N = 147; CC, N = 141) but not in adolescents after 1-dose BNT162b2 (B, N = 116). CC induces SARS-CoV-2 N and N C-terminal domain seropositivity in a higher proportion of adolescents than adults. Adverse reactions are mostly mild for both vaccines and more frequent for BNT162b2. We find higher S, neutralising, avidity and Fc receptor-binding antibody responses in adolescents receiving BB than CC, and a similar induction of strong S-specific T cells by the 2 vaccines, in addition to N- and M-specific T cells induced by CoronaVac but not BNT162b2, possibly implying differential durability and cross-variant protection by BNT162b2 and CoronaVac, the 2 most used SARS-CoV-2 vaccines worldwide. Our results support the use of both vaccines in adolescents.