Risk of hospital admission and death from first-ever SARS-CoV-2 infection by age group during the Delta and Omicron periods in British Columbia, Canada.

BACKGROUND: Population-based cross-sectional serosurveys within the Lower Mainland, British Columbia, Canada, showed about 10%, 40% and 60% of residents were infected with SARS-CoV-2 by the sixth (September 2021), seventh (March 2022) and eighth (July 2022) serosurveys. We conducted the ninth (December 2022) and tenth (July 2023) serosurveys and sought to assess risk of severe outcomes from a first-ever SARS-CoV-2 infection during intersurvey periods. METHODS: Using increments in cumulative infection-induced seroprevalence, population census, discharge abstract and vital statistics data sets, we estimated infection hospitalization and fatality ratios (IHRs and IFRs) by age and sex for the sixth to seventh (Delta/Omicron-BA.1), seventh to eighth (Omicron-BA.2/BA.5) and eighth to ninth (Omicron-BA.5/BQ.1) intersurvey periods. As derived, IHR and IFR estimates represent the risk of severe outcome from a first-ever SARS-CoV-2 infection acquired during the specified intersurvey period. RESULTS: The cumulative infection-induced seroprevalence was 74% by December 2022 and 79% by July 2023, exceeding 80% among adults younger than 50 years but remaining less than 60% among those aged 80 years and older. Period-specific IHR and IFR estimates were consistently less than 0.3% and 0.1% overall. By age group, IHR and IFR estimates were less than 1.0% and up to 0.1%, respectively, except among adults aged 70-79 years during the sixth to seventh intersurvey period (IHR 3.3% and IFR 1.0%) and among those aged 80 years and older during all periods (IHR 4.7%, 2.2% and 3.5%; IFR 3.3%, 0.6% and 1.3% during the sixth to seventh, seventh to eighth and eighth to ninth periods, respectively). The risk of severe outcome followed a J-shaped age pattern. During the eighth to ninth period, we estimated about 1 hospital admission for COVID-19 per 300 newly infected children younger than 5 years versus about 1 per 30 newly infected adults aged 80 years and older, with no deaths from COVID-19 among children but about 1 death per 80 newly infected adults aged 80 years and older during that period. INTERPRETATION: By July 2023, we estimated about 80% of residents in the Lower Mainland, BC, had been infected with SARS-CoV-2 overall, with low risk of hospital admission or death; about 40% of the oldest adults, however, remained uninfected and at highest risk of a severe outcome. First infections among older adults may still contribute substantial burden from COVID-19, reinforcing the need to continue to prioritize this age group for vaccination and to consider them in health care system planning.

Vaccine effectiveness estimates from an early-season influenza A(H3N2) epidemic, including unique genetic diversity with reassortment, Canada, 2022/23.

The Canadian Sentinel Practitioner Surveillance Network estimated vaccine effectiveness (VE) during the unusually early 2022/23 influenza A(H3N2) epidemic. Like vaccine, circulating viruses were clade 3C.2a1b.2a.2, but with genetic diversity affecting haemagglutinin positions 135 and 156, and reassortment such that H156 viruses acquired neuraminidase from clade 3C.2a1b.1a. Vaccine provided substantial protection with A(H3N2) VE of 54% (95% CI: 38 to 66) overall. VE was similar against H156 and vaccine-like S156 viruses, but with potential variation based on diversity at position 135.

BNT162b2 Effectiveness Against Delta and Omicron Variants of Severe Acute Respiratory Syndrome Coronavirus 2 in Adolescents Aged 12-17 Years, by Dosing Interval and Duration.

BACKGROUND: Two- and 3-dose BNT162b2 vaccine effectiveness (VE) against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, including Delta and Omicron variants, was assessed among adolescents in Canada, where first and second doses were spaced longer than the manufacturer-specified 3-week interval. METHODS: Test-negative design estimated VE against laboratory-confirmed SARS-CoV-2 infection ≥14 days after vaccination among 12-17-year-olds in Quebec and British Columbia, Canada, between 5 September 2021 and 30 April 2022 (epidemiological weeks 36-17). VE was explored by the interval between first and second doses, time since the second dose, and with a third dose. RESULTS: The VE against Delta was ≥90% until at least 5 months after the second dose. The VE against Omicron decreased from about 65%-75% at 2-3 weeks to ≤50% by the third month after vaccination, restored to approximately 65% by a third dose. Although confidence intervals overlapped, VE against Omicron was about 5%-7% higher (absolute) when first and second doses were spaced ≥8 versus 3-4 weeks apart. CONCLUSIONS: In adolescents, 2 BNT162b2 doses provided strong and sustained protection against Delta but reduced and rapidly waning VE against Omicron. A longer interval between first and second doses and a third dose marginally improved Omicron protection.

Serial cross-sectional estimation of vaccine-and infection-induced SARS-CoV-2 seroprevalence in British Columbia, Canada.

BACKGROUND: The evolving proportion of the population considered immunologically naive versus primed for more efficient immune memory response to SARS-CoV-2 has implications for risk assessment. We sought to chronicle vaccine- and infection-induced seroprevalence across the first 7 waves of the COVID-19 pandemic in British Columbia, Canada. METHODS: During 8 cross-sectional serosurveys conducted between March 2020 and August 2022, we obtained anonymized residual sera from children and adults who attended an outpatient laboratory network in the Lower Mainland (Greater Vancouver and Fraser Valley). We used at least 3 immunoassays per serosurvey to detect SARS-CoV-2 spike and nucleocapsid antibodies. We assessed any seroprevalence (vaccineor infection-induced, or both), defined by positivity on any 2 assays, and infection-induced seroprevalence, also defined by dual-assay positivity but requiring both antinucleocapsid and antispike detection. We used estimates of infection-induced seroprevalence to explore underascertainment of infections by surveillance case reports. RESULTS: By January 2021, we estimated that any seroprevalence remained less than 5%, increasing with vaccine rollout to 56% by May-June 2021, 83% by September-October 2021 and 95% by March 2022. Infection-induced seroprevalence remained less than 15% through September-October 2021, increasing across Omicron waves to 42% by March 2022 and 61% by July-August 2022. By August 2022, 70%-80% of children younger than 20 years and 60%-70% of adults aged 20-59 years had been infected, but fewer than half of adults aged 60 years and older had been infected. Compared with estimates of infection-induced seroprevalence, surveillance case reports underestimated infections 12-fold between September 2021 and March 2022 and 92-fold between March 2022 and August 2022. INTERPRETATION: By August 2022, most children and adults younger than 60 years had evidence of both SARS-CoV-2 vaccination and infection. As previous evidence suggests that a history of both exposures may induce stronger, more durable hybrid immunity than either exposure alone, older adults - who have the lowest infection rates but highest risk of severe outcomes - continue to warrant prioritized vaccination.

Influenza vaccine effectiveness against A(H3N2) during the delayed 2021/22 epidemic in Canada.

Influenza virus circulation virtually ceased in Canada during the COVID-19 pandemic, re-emerging with the relaxation of restrictions in spring 2022. Using a test-negative design, the Canadian Sentinel Practitioner Surveillance Network reports 2021/22 vaccine effectiveness of 36% (95% CI: -38 to 71) against late-season illness due to influenza A(H3N2) clade 3C.2a1b.2a.2 viruses, considered antigenically distinct from the 3C.2a1b.2a.1 vaccine strain. Findings reinforce the World Health Organization's decision to update the 2022/23 northern hemisphere vaccine to a more representative A(H3N2) clade 3C.2a1b.2a.2 strain.

Policies and interventions to remove gender-related barriers to girls' school participation and learning in low- and middle-income countries: A systematic review of the evidence.

Background: Gender disparities in education continue to undermine girls' opportunities, despite enormous strides in recent years to improve primary enrolment and attainment for girls in low- and middle-income countries (LMICs). At the regional, country and subnational levels gender gaps remain, with girls in many settings less likely to complete primary school, less likely to complete secondary, and often less likely to be literate than boys. The academic and policy literatures on the topic of gender-related barriers to girls' education are both extensive. However, there remain gaps in knowledge regarding which interventions are most likely to work in contexts with different combinations of barriers. Objectives: This systematic review identified and assessed the strength of the evidence of interventions and exposures addressing gender-related barriers to schooling for girls in LMICs. Search Methods: The AEA RCT Registry, Africa Bibliography, African Education Research Database, African Journals Online, DEC USAID, Dissertation Abstracts, EconLit, ELDIS, Evidence Hub, Global Index Medicus, IDEAS-Repec, Intl Clinical Trials Registry, NBER, OpenGrey, Open Knowledge Repository, POPLINE, PsychINFO, PubMed, Research for Development Outputs, ScienceDirect, Sociological Abstracts, Web of Science, as well as relevant organization websites were searched electronically in March and April of 2019. Further searches were conducted through review of bibliographies as well as through inquiries to authors of included studies, relevant researchers and relevant organizations, and completed in March 2020. Selection Criteria: We included randomized controlled trials as well as quasi-experimental studies that used quantitative models that attempted to control for endogeneity. Manuscripts could be either published, peer-reviewed articles or grey literature such as working papers, reports and dissertations. Studies must have been published on or after 2000, employed an intervention or exposure that attempted to address a gender-related barrier to schooling, analyzed the effects of the intervention/exposure on at least one of our primary outcomes of interest, and utilized data from LMICs to be included. Data Collection and Analysis: A team of reviewers was grouped into pairs to independently screen articles for relevance, extract data and assess risk of bias for each included study. A third reviewer assisted in resolving any disputes. Risk of bias was assessed either through the RoB 2 tool for experimental studies or the ROBINS-I tool for quasi-experimental studies. Due to the heterogeneity of study characteristics and reported outcome measures between studies, we applied the GRADE (Grading of Recommendation, Assessment, Development and Evaluation) approach adapted for situations where a meta-analysis is not possible to synthesize the research. Results: Interventions rated as effective exist for three gender-related barriers: inability to afford tuition and fees, lack of adequate food, and insufficient academic support. Promising interventions exist for three gender-related barriers: inadequate school access, inability to afford school materials, and lack of water and sanitation. More research is needed for the remaining 12 gender-related barriers: lack of support for girls' education, child marriage and adolescent pregnancy, lack of information on returns to education/alternative roles for women, school-related gender-based violence (SRGBV), lack of safe spaces and social connections, inadequate sports programs for girls, inadequate health and childcare services, inadequate life skills, inadequate menstrual hygiene management (MHM), poor policy/legal environment, lack of teaching materials and supplies, and gender-insensitive school environment. We find substantial gaps in the evidence. Several gender-related barriers to girls' schooling are under-examined. For nine of these barriers we found fewer than 10 relevant evaluations, and for five of the barriers-child marriage and adolescent pregnancy, SRGBV, inadequate sports programs for girls, inadequate health and childcare services, and inadequate MHM-we found fewer than five relevant evaluations; thus, more research is needed to understand the most effective interventions to address many of those barriers. Also, nearly half of programs evaluated in the included studies were multi-component, and most evaluations were not designed to tease out the effects of individual components. As a result, even when interventions were effective overall, it is often difficult to identify how much, if any, of the impact is attributable to a given program component. The combination of components varies between studies, with few comparable interventions, further limiting our ability to identify packages of interventions that work well. Finally, the context-specific nature of these barriers-whether a barrier exists in a setting and how it manifests and operates-means that a program that is effective in one setting may not be effective in another. Authors' Conclusions: While some effective and promising approaches exist to address gender-related barriers to education for girls, evidence gaps exist on more than half of our hypothesized gender-related barriers to education, including lack of support for girls' education, SRGBV, lack of safe spaces and social connections, inadequate life skills, and inadequate MHM, among others. In some cases, despite numerous studies examining interventions addressing a specific barrier, studies either did not disaggregate results by sex, or they were not designed to isolate the effects of each intervention component. Differences in context and in implementation, such as the number of program components, curricula content, and duration of interventions, also make it difficult to compare interventions to one another. Finally, few studies looked at pathways between interventions and education outcomes, so the reasons for differences in outcomes largely remain unclear.

The Adolescent Data Hub: The Largest Catalog of Open Access Data on Adolescents Living in Low- and Middle-Income Countries.

The Adolescent Data Hub (ADH) is the first and largest data catalog specifically developed to focus on open access data on adolescents in low- and middle-income countries (LMICs). Developed by the Population Council's Girl Innovation, Research, and Learning (GIRL) Center, and launched in August 2018, the ADH has grown to include more than 750 data sources that fit the inclusion criteria of (1) self-reported data from females and/or males between ages 10 and 24 years; (2) one or more rounds of data collected in year 2000 or later; (3) data collected in one or more LMICs; (4) data are publicly available for download and use. A dynamic resource, the ADH is regularly updated to include new datasets that meet these criteria. The ADH facilitates access to available data on adolescents for researchers attempting to answer important questions related to the lives of adolescents and for donors and policymakers eager to identify gaps in existing data to inform their future investments.

Causal effects of education on sexual and reproductive health in low and middle-income countries: A systematic review and meta-analysis.

BACKGROUND: Despite strong theoretical grounding, important gaps in knowledge remain regarding the degree to which there is a causal relationship between education and sexual and reproductive health, as many claims have been made based on associations alone. Understanding the extent to which these relationships are causal is important both to inform investments in education and health, as well as to understand the mechanisms underlying these relationships. METHODS: We conducted a systematic review of the evidence for a causal link between education and sexual and reproductive health (SRH) in low and middle-income countries. Education indicators included exposure to formal schooling and learning. SRH outcomes included: age at first sex, age at first marriage, age at first pregnancy/birth, contraceptive use, fertility, and HIV status and other sexually transmitted infections. When possible, we also conducted meta-analyses to estimate mean effects by outcome, and to understand sources of variation between studies. RESULTS: We identified 35 papers that met our inclusion criteria. Although many of the studies report evidence of a causal relationship between education and one or more SRH outcomes, estimated effects are often small in magnitude. Our meta-analyses reveal mostly null mean effects, with the exception of small effects of increased grade attainment on lower fertility and HIV positive status. We also found inconsistent evidence supporting mechanisms linking education and SRH. CONCLUSIONS: This review demonstrates that, although investments in schooling may have positive ripple effects for sexual and reproductive health in some circumstances, those effects may not be as large or consistent as expected. Further, our understanding of the circumstances in which schooling is most likely to improve SRH remains somewhat limited. An accurate picture of whether and when improvements in education lead to better health outcomes is essential for the achievement of global development goals.

Evidence for causal links between education and maternal and child health: systematic review.

OBJECTIVE: Numerous studies have documented an inverse association between years of schooling attained, particularly by women, and reduced maternal, infant and child mortality. However, if factors affecting educational attainment - many of which are unobservable, e.g. motivation and genetic endowment - also affect the likelihood of engaging in behaviours that enhance health, then assumed effects of schooling will be inflated in analyses that do not address this endogeneity. This systematic review assesses evidence for a causal link between education and maternal and child health in low and middle-income countries. METHODS: Eligible studies controlled for observable and unobservable factors affecting both education and health. Reported effects were converted into partial correlations. When possible, we also conducted meta-analyses to estimate mean effects by outcome. RESULTS: Of 4952 papers identified, 16 met the inclusion criteria. The 15 child health papers examined neonatal, infant and child mortality, stunting and wasting. Significant effects of education on infant and child health were observed for 30 of 33 models that did not account for endogeneity. In contrast, only 18 of 46 effects were significant in models that addressed endogeneity. Notably, for only one outcome -child mortality measured dichotomously -was the effect of maternal educational attainment significant in a meta-analysis. The one maternal morbidity paper found significant effects for the two preventable outcomes considered. CONCLUSION: While we find evidence for a causal link between education and health, effects are weaker in models that address endogeneity compared to naïve models that do not account for unobservable factors affecting both education and health. Advances in women's educational outcomes have undoubtedly played a role in improving health in many settings; however, the effect is not as strong as some researchers and advocates have claimed.

OBJECTIF: De nombreuses études ont montré une association inverse entre le nombre d'années de scolarité atteintes, en particulier par les femmes, et la réduction de la mortalité maternelle, infantile et des nourrissons. Cependant, si les facteurs affectant le niveau d'éducation - dont beaucoup sont non observables, tels que la motivation et le patrimoine génétique - affectent également la probabilité d'adopter des comportements qui améliorent la santé, les effets supposés de la scolarité seront alors gonflés dans des analyses ne traitant pas de cette endogénicité. Cette analyse systématique évalue la preuve d'un lien de causalité entre l'éducation et la santé maternelle et infantile dans les pays à revenu faible ou intermédiaire. MÉTHODES: Les études éligibles contrôlaient les facteurs observables et non observables affectant à la fois l'éducation et la santé. Les effets rapportés ont été convertis en corrélations partielles. Dans la mesure du possible, nous avons également effectué des méta-analyses pour estimer les effets moyens par résultat. RÉSULTATS: Sur 4.952 articles identifiés, 16 répondaient aux critères d'inclusion. Les 15 articles sur la santé infantile ont examiné la mortalité néonatale, infantile et du nourrisson, le retard de croissance et l'émaciation. Des effets significatifs de l'éducation sur la santé du nourrisson et de l'enfant ont été observés pour 30 des 33 modèles qui n'ont pas tenu compte de l'endogénicité. En revanche, seuls 18 des 46 effets étaient significatifs dans les modèles traitant de l'endogénicité. Notamment, pour un seul résultat - la mortalité infantile mesurée de manière dichotomique - dans une méta-analyse, l'effet du niveau d'éducation de la mère était significatif. Le seul article sur la morbidité maternelle a révélé des effets significatifs sur les deux résultats évitables considérés. CONCLUSION: Bien que nous trouvons des preuves d'un lien de causalité entre l'éducation et la santé, les effets des modèles qui traitent de l'endogénicité sont plus faibles que ceux des modèles naïfs qui ne tiennent pas compte de facteurs non observables affectant à la fois l'éducation et la santé. Les progrès dans les résultats scolaires des femmes ont incontestablement joué un rôle dans l'amélioration de la santé dans de nombreux contextes; cependant, l'effet n'est pas aussi puissant que certains chercheurs et défenseurs le prétendent.