The degree to which children and adolescents are infected by and transmit severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is unclear. The role of children and adolescents in transmission of SARS-CoV-2 is dependent on susceptibility, symptoms, viral load, social contact patterns, and behavior. OBJECTIVE To systematically review the susceptibility to and transmission of SARS-CoV-2 among children and adolescents compared with adults. DATA SOURCES PubMed and medRxiv were searched from database inception to July 28, 2020, and a total of 13 926 studies were identified, with additional studies identified through hand searching of cited references and professional contacts. STUDY SELECTION Studies that provided data on the prevalence of SARS-CoV-2 in children and adolescents (younger than 20 years) compared with adults (20 years and older) derived from contact tracing or population screening were included. Single-household studies were excluded. DATA EXTRACTION AND SYNTHESIS PRISMA guidelines for abstracting data were followed, which was performed independently by 2 reviewers. Quality was assessed using a critical appraisal checklist for prevalence studies. Random-effects meta-analysis was undertaken. MAIN OUTCOMES AND MEASURES Secondary infection rate (contact-tracing studies) or prevalence or seroprevalence (population screening studies) among children and adolescents compared with adults. RESULTS A total of 32 studies comprising 41 640 children and adolescents and 268 945 adults met inclusion criteria, including 18 contact-tracing studies and 14 population screening studies. The pooled odds ratio of being an infected contact in children compared with adults was 0.56 (95% CI, 0.37-0.85), with substantial heterogeneity (I 2 = 94.6%). Three school-based contact-tracing studies found minimal transmission from child or teacher index cases. Findings from population screening studies were heterogenous and were not suitable for meta-analysis. Most studies were consistent with lower seroprevalence in children compared with adults, although seroprevalence in adolescents appeared similar to adults. CONCLUSIONS AND RELEVANCE In this meta-analysis, there is preliminary evidence that children and adolescents have lower susceptibility to SARS-CoV-2, with an odds ratio of 0.56 for being an infected contact compared with adults. There is weak evidence that children and adolescents play a lesser role than adults in transmission of SARS-CoV-2 at a population level. This study provides no information on the infectivity of children.

Massive slums have become major features of cities in many low-income and middle-income countries. Here, in the first in a Series of two papers, we discuss why slums are unhealthy places with especially high risks of infection and injury. We show that children are especially vulnerable, and that the combination of malnutrition and recurrent diarrhoea leads to stunted growth and longer-term effects on cognitive development. We find that the scientific literature on slum health is underdeveloped in comparison to urban health, and poverty and health. This shortcoming is important because health is affected by factors arising from the shared physical and social environment, which have effects beyond those of poverty alone. In the second paper we will consider what can be done to improve health and make recommendations for the development of slum health as a field of study.

Background Attention to women’s and girls’ menstrual needs is critical for global health and gender equality. The importance of this neglected experience has been elucidated by a growing body of qualitative research, which we systematically reviewed and synthesised. Methods and findings We undertook systematic searching to identify qualitative studies of women’s and girls’ experiences of menstruation in low- and middle-income countries (LMICs). Of 6,892 citations screened, 76 studies reported in 87 citations were included. Studies captured the experiences of over 6,000 participants from 35 countries. This included 45 studies from sub-Saharan Africa (with the greatest number of studies from Kenya [ n = 7], Uganda [ n = 6], and Ethiopia [ n = 5]), 21 from South Asia (including India [ n = 12] and Nepal [ n = 5]), 8 from East Asia and the Pacific, 5 from Latin America and the Caribbean, 5 from the Middle East and North Africa, and 1 study from Europe and Central Asia. Through synthesis, we identified overarching themes and their relationships to develop a directional model of menstrual experience. This model maps distal and proximal antecedents of menstrual experience through to the impacts of this experience on health and well-being. The sociocultural context, including menstrual stigma and gender norms, influenced experiences by limiting knowledge about menstruation, limiting social support, and shaping internalised and externally enforced behavioural expectations. Resource limitations underlay inadequate physical infrastructure to support menstruation, as well as an economic environment restricting access to affordable menstrual materials. Menstrual experience included multiple themes: menstrual practices, perceptions of practices and environments, confidence, shame and distress, and containment of bleeding and odour. These components of experience were interlinked and contributed to negative impacts on women’s and girls’ lives. Impacts included harms to physical and psychological health as well as education and social engagement. Our review is limited by the available studies. Study quality was varied, with 18 studies rated as high, 35 medium, and 23 low trustworthiness. Sampling and analysis tended to be untrustworthy in lower-quality studies. Studies focused on the experiences of adolescent girls were most strongly represented, and we achieved early saturation for this group. Reflecting the focus of menstrual health research globally, there was an absence of studies focused on adult women and those from certain geographical areas. Conclusions Through synthesis of extant qualitative studies of menstrual experience, we highlight consistent challenges and developed an integrated model of menstrual experience. This model hypothesises directional pathways that could be tested by future studies and may serve...

Complex systems approaches to social intervention research are increasingly advocated. However, there have been few attempts to consider how models of intervention science, such as the UK’s Medical Research Council complex interventions framework, might be reframed through a complex systems lens. This article identifies some key areas in which this framework might be reconceptualized, and a number of priority areas where further development is needed if alignment with a systems perspective is to be achieved. We argue that a complex systems perspective broadens the parameters of ‘relevant’ evidence and theory for intervention development, before discussing challenges in defining feasibility in dynamic terms. We argue that whole systems evaluations may be neither attainable, nor necessary; acknowledgment of complexity does not mean that evaluations must be complex, or investigate all facets of complexity. However, a systems lens may add value to evaluation design through guiding identification of key uncertainties, and informing decisions such as timings of follow-up assessments.

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To our knowledge, this is the first systematic, meta-analytic review of all risk and protective factors for IPV against women without location, time, or publication restrictions. Unplanned pregnancy and having parents with less than a high-school education, which may indicate lower socioeconomic status, were shown to be risk factors, and being older or married were protective. However, no prospective-longitudinal study investigated the associations between IPV against women and any community or structural factor outside the United States, and more studies investigated risk factors related to women as opposed to their partners. Public health implications. This review highlights that prospective evidence for perpetrator- and context-related risk and protective factors for women's experiences of IPV outside of the United States is lacking and urgently needed to inform global policy recommendations. The current evidence base of prospective studies suggests that, at least in the United States, education and sexual health interventions may be effective targets for preventing IPV against women, with young, unmarried women at greatest risk.

Parenting programs are the recommended strategy for the prevention and treatment of disruptive child behavior. Similar to most psychosocial interventions, it is unknown which components of parenting programs (ie, parenting techniques taught) actually contribute to program effects. Identifying what parents need to be taught to reduce disruptive child behavior can optimize intervention strategies, and refine theories on how parenting shapes disruptive child behavior. Method: In two meta-analyses, we updated the evidence-base for effectiveness of parenting programs delivered at various levels of prevention and treatment of disruptive behavior. We searched six databases (eg, PsycINFO, MEDLINE) for randomized trials and coded the parenting techniques taught in each program. We identified the techniques associated with program effects in general, and for prevention versus treatment, and immediate versus longer-term effects, specifically. Results: Parenting program effects on disruptive behavior gradually increased per level of prevention (universal d ¼ À0.21, selective d ¼ À0.27, indicated d ¼ À0.55) and treatment (d ¼ À0.69) (Meta-Analysis 1: 154 trials, 398 effect sizes). Three of 26 parenting techniques were associated with stronger program effects: positive reinforcement, praise in particular, and natural/logical consequences. Several additional techniques (eg, relationship building and parental self-management) were associated with stronger effects in treatment but weaker effects in prevention. No techniques were associated with stronger longer-term effects (Meta-Analysis 2: 42 trials, 157 effect sizes). Conclusion: Positive reinforcement and nonviolent discipline techniques (eg, applying natural/logical consequences) seem to be key parenting program techniques to reduce disruptive child behavior. Additional techniques (eg, parental self-management skills) might improve program effects in treatment, but not in prevention.