Suicide is a major global health challenge and a leading cause of death among adolescents, but research related to suicide has concentrated on high-income countries. We aimed to estimate the prevalence of suicidal ideation, suicide planning, and suicide attempts in adolescents from 59 low-income and middle-income countries. In this population-based study, we used data from the Global School-based Student Health Survey of schoolchildren aged 13-17 years between 2003 and 2015, in 59 low-income and middle-income countries across six WHO regions. Using a meta-analysis with random effects, we computed the sex-based and age-based estimates of regional and overall prevalence of suicidal ideation, suicide planning, and suicide attempts. Our sample consisted of 229 129 adolescents (mean age 14·6 [SD 1·18] years; 111 082 [48%] boys and 118 047 [52%] girls). The overall prevalence of suicidal ideation was 16·9% (95% CI 15·0-18·8), suicide planning was 17·0% (14·8-19·2), and suicide attempts was 17·0% (14·7-19·3) in the 12 months preceding survey completion. The African region had the highest prevalence of suicidal ideation (20·4%, 17·3-23·6) and suicide planning (23·7%, 19·1-28·3), and the western Pacific region had the highest prevalence of suicide attempts (20·5%, 14·3-26·7). Southeast Asia had the lowest prevalence of ideation (8·0%, 4·5-11·5), planning (9·9%, 5·0-14·8), and attempts (9·2%, 5·1-13·3). Girls had higher prevalence than boys for suicidal ideation (18·5%, 16·4-20·6 vs 15·1%, 13·4-16·7), suicide planning (18·2%, 15·8-20·6 vs 15·6%, 13·7-17·6), and suicide attempts (17·4%, 15·0-19·8 vs 16·3%, 14·0-18·6). Adolescents aged 15-17 years had higher prevalence than those aged 13-14 years of suicidal ideation (17·8%, 15·8-19·8 vs 15·9%, 14·1-17·6), suicide planning (17·8%, 15·7-20·0 vs 16·3%, 14·7-17·9), and suicide attempts (17·6%, 15·2-20·0 vs 16·2%, 13·8-18·5). Suicidal thoughts and behaviours are prevalent among adolescents in low-income and middle-income countries, particularly in the African and the western Pacific regions, and particularly among girls and adolescents aged 15-17 years. Targeted suicide prevention initiatives are needed and should take into account the diverse range of cultural and socioeconomic backgrounds of the countries. None.

Vaccine protection from symptomatic SARS-CoV-2 infection has been shown to be strongly correlated with neutralising antibody titres; however, this has not yet been demonstrated for severe COVID-19. To explore whether this relationship also holds for severe COVID-19, we performed a systematic search for studies reporting on protection against different SARS-CoV-2 clinical endpoints and extracted data from 15 studies. Since matched neutralising antibody titres were not available, we used the vaccine regimen, time since vaccination and variant of concern to predict corresponding neutralising antibody titres. We then compared the observed vaccine effectiveness reported in these studies to the protection predicted by a previously published model of the relationship between neutralising antibody titre and vaccine effectiveness against severe COVID-19. We find that predicted neutralising antibody titres are strongly correlated with observed vaccine effectiveness against symptomatic (Spearman $$\rho$$ρ = 0.95, p < 0.001) and severe (Spearman $$\rho$$ρ = 0.72, p < 0.001 for both) COVID-19 and that the loss of neutralising antibodies over time and to new variants are strongly predictive of observed vaccine protection against severe COVID-19.

Although parental and peer support can influence adolescents’ physical activity (PA), these associations have not been fully examined through a global assessment. This study examined the associations of parental and peer support with PA among adolescents from 74 countries. The Global School-based Student Health Survey data from 250,317 adolescents aged 11–17 years (48.8% girls), collected between 2007 and 2016, were analysed. Adolescents were asked how many days/week they were physically active and about their parental and peer support. Meta-analysis showed that adolescents who had high parental or peer support had higher odds of attaining sufficient PA (odds ratio (OR): 1.40, 95% confidence interval (CI): 1.34–1.46; OR: 1.57, 95% CI: 1.49–1.65, respectively). Pooled estimates of association were significant across all World Health Organization (WHO) regions and country-income categories with the highest estimate from the low-income countries. The Western Pacific region showed the highest association between parental support and adolescents’ PA (OR: 1.49, 95% CI: 1.41–1.59), while South-East Asia exhibited the highest association between peer support and adolescents’ PA (OR: 1.80, 95% CI: 1.59–2.04). Country-level estimates of associations are presented. Future studies should use robust assessment of PA and PA-specific parental and peer support with emphasis on qualitative investigation to understand the complexity of the relationships.

The Modified Vaccinia Ankara vaccine developed by Bavarian Nordic (MVA-BN) was widely deployed to prevent mpox during the 2022 global outbreak. This vaccine was initially approved for mpox based on its reported immunogenicity (from phase I/II trials) and effectiveness in animal models, rather than evidence of clinical efficacy. However, no validated correlate of protection after vaccination has been identified. Here we performed a systematic search and meta-analysis of the available data to test whether vaccinia-binding ELISA endpoint titer is predictive of vaccine effectiveness against mpox. We observe a significant correlation between vaccine effectiveness and vaccinia-binding antibody titers, consistent with the existing assumption that antibody levels may be a correlate of protection. Combining this data with analysis of antibody kinetics after vaccination, we predict the durability of protection after vaccination and the impact of dose spacing. We find that delaying the second dose of MVA-BN vaccination will provide more durable protection and may be optimal in an outbreak with limited vaccine stock. Although further work is required to validate this correlate, this study provides a quantitative evidence-based approach for using antibody measurements to predict the effectiveness of mpox vaccination.