Estimated impact of the pneumococcal conjugate vaccine on pneumonia mortality in South Africa, 1999 through 2016: An ecological modelling study

Estimated Population-Level Impact of Pneumococcal Conjugate Vaccines Against All-Cause Pneumonia Mortality Among Unvaccinated in 5 Latin American Countries

BACKGROUND

Pneumococcal conjugate vaccines (PCVs) provide strong direct protection in children, while limited data are available on their indirect effect on mortality among older age groups. This multicountry study aimed to assess the population-level impact of pediatric PCVs on all-cause pneumonia mortality among children ≥5 years of age, and invasive pneumococcal disease (IPD) cases in Chile.

METHODS

Demographic and mortality data from Argentina, Brazil, Chile, Colombia, and Mexico were collected considering the ≥ 5-year-old population, from 2000 to 2019, with 1 795 789 deaths due to all-cause pneumonia. IPD cases in Chile were also evaluated. Time series models were employed to evaluate changes in all-cause pneumonia deaths during the postvaccination period, with other causes of death used as synthetic controls for unrelated temporal trends.

RESULTS

No significant change in death rates due to all-cause pneumonia was detected following PCV introduction among most age groups and countries. The proportion of IPD cases caused by vaccine serotypes decreased from 29% (2012) to 6% (2022) among people aged ≥65 years in Chile.

DISCUSSION

While an effect of PCV against pneumonia deaths (a broad clinical definition that may not be specific enough to measure indirect effects) was not detected, evidence of indirect PCV impact was observed among vaccine-type-specific IPD cases.

Geographical migration and fitness dynamics of Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of pneumonia and meningitis worldwide. Many different serotypes co-circulate endemically in any one location1,2. The extent and mechanisms of spread and vaccine-driven changes in fitness and antimicrobial resistance remain largely unquantified. Here using geolocated genome sequences from South Africa (n = 6,910, collected from 2000 to 2014), we developed models to reconstruct spread, pairing detailed human mobility data and genomic data. Separately, we estimated the population-level changes in fitness of strains that are included (vaccine type (VT)) and not included (non-vaccine type (NVT)) in pneumococcal conjugate vaccines, first implemented in South Africa in 2009. Differences in strain fitness between those that are and are not resistant to penicillin were also evaluated. We found that pneumococci only become homogenously mixed across South Africa after 50 years of transmission, with the slow spread driven by the focal nature of human mobility. Furthermore, in the years following vaccine implementation, the relative fitness of NVT compared with VT strains increased (relative risk of 1.68; 95% confidence interval of 1.59-1.77), with an increasing proportion of these NVT strains becoming resistant to penicillin. Our findings point to highly entrenched, slow transmission and indicate that initial vaccine-linked decreases in antimicrobial resistance may be transient.

Antigen non-specific CD8+ T cells accelerate cognitive decline in aged mice following respiratory coronavirus infection

Primarily a respiratory infection, numerous patients infected with SARS-CoV-2 present with neurologic symptoms, some continuing long after viral clearance as a persistent symptomatic phase termed "long COVID". Advanced age increases the risk of severe disease, as well as incidence of long COVID. We hypothesized that perturbations in the aged immune response predispose elderly individuals to severe coronavirus infection and post-infectious sequelae. Using a murine model of respiratory coronavirus, mouse hepatitis virus strain A59 (MHV-A59), we found that aging increased clinical illness and lethality to MHV infection, with aged animals harboring increased virus in the brain during acute infection. This was coupled with an unexpected increase in activated CD8+ T cells within the brains of aged animals but reduced antigen specificity of those CD8+ T cells. Aged animals demonstrated spatial learning impairment following MHV infection, which correlated with increased neuronal cell death and reduced neuronal regeneration in aged hippocampus. Using primary cell culture, we demonstrated that activated CD8+ T cells induce neuronal death, independent of antigen-specificity. Specifically, higher levels of CD8+ T cell-derived IFN-γ correlated with neuronal death. These results support the evidence that CD8+ T cells in the brain directly contribute to cognitive dysfunction following coronavirus infection in aged individuals.

Using LASSO Regression to Estimate the Population-Level Impact of Pneumococcal Conjugate Vaccines

Pneumococcal conjugate vaccines (PCVs) protect against diseases caused by Streptococcus pneumoniae, such as meningitis, bacteremia, and pneumonia. It is challenging to estimate their population-level impact due to the lack of a perfect control population and the subtleness of signals when the endpoint-such as all-cause pneumonia-is nonspecific. Here we present a new approach for estimating the impact of PCVs: using least absolute shrinkage and selection operator (LASSO) regression to select variables in a synthetic control model to predict the counterfactual outcome for vaccine impact inference. We first used a simulation study based on hospitalization data from Mexico (2000-2013) to test the performance of LASSO and established methods, including the synthetic control model with Bayesian variable selection (SC). We found that LASSO achieved accurate and precise estimation, even in complex simulation scenarios where the association between the outcome and all control variables was noncausal. We then applied LASSO to real-world hospitalization data from Chile (2001-2012), Ecuador (2001-2012), Mexico (2000-2013), and the United States (1996-2005), and found that it yielded estimates of vaccine impact similar to SC. The LASSO method is accurate and easily implementable and can be applied to study the impact of PCVs and other vaccines.

Value of diagnostic vaccination in diagnosis of humoral inborn errors of immunity

Inborn errors of immunity (IEIs) or primary immunodeficiency diseases, are disorders caused by genetic defects affecting immune function. Clinically, IEI presents mainly as recurrent or severe infections, immune dysregulation (autoimmunity or autoinflammatory disorders), and lymphoproliferation with or without dysmorphic features. Humoral IEIs are the largest subgroup of IEI, with a wide spectrum of quantitative and qualitative antibody defects. These disorders are normally diagnosed based on immunological evaluation; diagnostic vaccination is part of this evaluation. This review examines the importance and relevance of diagnostic vaccination in the diagnosis of humoral IEIs and different technologies which can be utilised in diagnosis.

Geographic migration and vaccine-induced fitness changes of Streptococcus pneumoniae

Streptococcus pneumoniae is a leading cause of pneumonia and meningitis worldwide. Many different serotypes co-circulate endemically in any one location. The extent and mechanisms of spread, and vaccine-driven changes in fitness and antimicrobial resistance (AMR), remain largely unquantified. Using geolocated genome sequences from South Africa (N=6910, 2000-2014) we developed models to reconstruct spread, pairing detailed human mobility data and genomic data. Separately we estimated the population level changes in fitness of strains that are (vaccine type, VT) and are not (non-vaccine type, NVT) included in the vaccine, first implemented in 2009, as well as differences in strain fitness between those that are and are not resistant to penicillin. We estimated that pneumococci only become homogenously mixed across South Africa after about 50 years of transmission, with the slow spread driven by the focal nature of human mobility. Further, in the years following vaccine implementation the relative fitness of NVT compared to VT strains increased (RR: 1.29 [95% CI 1.20-1.37]) - with an increasing proportion of these NVT strains becoming penicillin resistant. Our findings point to highly entrenched, slow transmission and indicate that initial vaccine-linked decreases in AMR may be transient.

Barriers and facilitators to nationwide implementation of the malaria vaccine in Ghana

Interventions such as antimalarial drugs, bed nets and insecticides have helped curb the burden of malaria in the past decade, yet malaria remains a leading cause of morbidity and mortality in children below the age of 5 years. In 2019, Ghana, Malawi and Kenya in sub-Saharan Africa (countries with moderate to high transmission areas of malaria and deaths) started piloting the RTS,S/AS01E malaria vaccine in selected regions. Using qualitative methods, this study examined the main factors (forces) that will influence or hinder the nationwide implementation of the malaria vaccine, if approved, in Ghana. We conducted in-depth interviews with 12 key individuals (national, research/academia and programme implementing partners) in the public health sector in Ghana from October 2018 to February 2019. Results were analysed using Kurt Lewin's force field analysis to understand how organizations interact with their external environment in the delivery of health policies such as the implementation of the malaria vaccine. We found that the disease burden of malaria deaths in Ghana, the efficacy of the vaccine, stakeholder involvement and evidence for the feasibility of vaccine delivery generated by the consortium of researchers (body of researchers) that can track the implementation were the driving forces to scale up the vaccine into a routine health system. On the other hand, the needed logistics, funding, administration of the four-dose vaccine and follow-up were identified as potential barriers. The most influential force collectively highlighted by the respondents was the disease burden, and the most influential barrier was the logistics of delivering the vaccine. Our findings provide decision makers with key barriers and facilitators to guide policy and decision-making for malaria control in Ghana and other similar settings in low- and middle-income countries.

Effectiveness of 13-valent pneumococcal conjugate vaccine on radiological primary end-point pneumonia among cases of severe community acquired pneumonia in children: A prospective multi-site hospital-based test-negative study in Northern India

INTRODUCTION

Community acquired pneumonia (CAP) is a leading cause of under-five mortality in India and Streptococcus pneumoniae is the main bacterial pathogen for it. Pneumococcal Conjugate Vaccine 13 (PCV13) has been introduced in a phased manner, in the national immunization program of India since 2017/2018. The primary objective of this study was to evaluate the effectiveness of PCV13 on chest radiograph (CXR)-confirmed pneumonia, in children hospitalized with WHO-defined severe CAP.

METHODS

This prospective, multi-site test-negative study was conducted in a hospital-network situated in three districts of Northern India where PCV13 had been introduced. Children aged 2-23 months, hospitalized with severe CAP and with interpretable CXR were included after parental consent. Clinical data was extracted from hospital records. CXRs were interpreted by a panel of three independent blinded trained radiologists. Exposure to PCV13 was defined as ≥2 doses of PCV13 in children aged ≤ 12 months and ≥ 1 dose(s) in children > 12 months of age. Our outcome measures were CXR finding of primary endpoint pneumonia with or without other infiltrates (PEP±OI); vaccine effectiveness (VE) and hospital mortality.

RESULTS

From 1st June 2017-30th April 2021, among 2711 children included, 678 (25.0%) were exposed to PCV1. CXR positive for PEP±OI on CXR was found in 579 (21.4%), of which 103 (17.8%) were exposed to PCV. Adjusted odds ratio (AOR) for PEP±OI among the exposed group was 0.69 (95% CI, 0.54-0.89, p = 0.004). Adjusted VE was 31.0% (95% CI: 11.0-44.0) for PEP±OI. AOR for hospital mortality with PEP±OI was 2.65 (95% CI: 1.27-5.53, p = 0.01).

CONCLUSION

In severe CAP, children exposed to PCV13 had significantly reduced odds of having PEP±OI. Since PEP±OI had increased odds of hospital mortality due to CAP, countrywide coverage with PCV13 is an essential priority.

A framework for managing health research capacity strengthening consortia: addressing tensions and enhancing capacity outcomes

There has been a steady increase in health research capacity strengthening (HRCS) consortia and programmes. However, their structures and management practices and the effect on the capacity strengthening outcomes have been underexamined. We conducted a case study involving three HRCS consortia where we critically examined the consortia's decision-making processes, strategies for resolving management tensions and the potential implications for consortia outcomes. We conducted 44 in-depth interviews with a range of consortia members and employed the framework method to analyse the data. We assessed the extent to which consortia's management practices and strategies enabled or hindered research capacity strengthening using a capacity development lens. At the heart of consortium management is how tensions are navigated and the resolution strategies adopted. This study demonstrates that the management strategies adopted by consortia have capacity strengthening consequences. When deciding on tension management strategies, trade-offs often occur, sometimes to the detriment of capacity strengthening aims. When management strategies align with capacity development principles, consortium management processes become capacity strengthening mechanisms for participating individuals and institutions. Such alignment enhances programme effectiveness and value for money. Drawing on these findings, we propose an evidence-informed management framework that consortia leaders can use in practice to support decision-making to optimise research capacity gains. Considering the increasing investment in HRCS consortia, leveraging all consortium processes towards capacity strengthening will maximise the returns on investments made.

Scalable psychological interventions for Syrian refugees in Europe and the Middle East: STRENGTHS study protocol for a prospective individual participant data meta-analysis

INTRODUCTION

The World Health Organization's (WHO) scalable psychological interventions, such as Problem Management Plus (PM+) and Step-by-Step (SbS) are designed to be cost-effective non-specialist delivered interventions to reduce symptoms of common mental disorders, such as anxiety, depression and post-traumatic stress disorder (PTSD). The STRENGTHS consortium aims to evaluate the effectiveness, cost-effectiveness and implementation of the individual format of PM+ and its group version (gPM+), as well as of the digital SbS intervention among Syrian refugees in seven countries in Europe and the Middle East. This is a study protocol for a prospective individual participant data (IPD) meta-analysis to evaluate (1) overall effectiveness and cost-effectiveness and (2) treatment moderators of PM+, gPM+ and SbS with Syrian refugees.

METHODS AND ANALYSIS

Five pilot randomised controlled trials (RCTs) and seven fully powered RCTs conducted within STRENGTHS will be combined into one IPD meta-analytic dataset. The RCTs include Syrian refugees of 18 years and above with elevated psychological distress (Kessler Psychological Distress Scale (K10>15)) and impaired daily functioning (WHO Disability Assessment Schedule 2.0 (WHODAS 2.0>16)). Participants are randomised into the intervention or care as usual control group, and complete follow-up assessments at 1-week, 3-month and 12-month follow-up. Primary outcomes are symptoms of depression and anxiety (25-item Hopkins Symptom Checklist). Secondary outcomes include daily functioning (WHODAS 2.0), PTSD symptoms (PTSD Checklist for DSM-5) and self-identified problems (PSYCHLOPS). We will conduct a one-stage IPD meta-analysis using linear mixed models. Quality of evidence will be assessed using the GRADE approach, and the economic evaluation approach will be assessed using the CHEC-list.

ETHICS AND DISSEMINATION

Local ethical approval has been obtained for each RCT. This IPD meta-analysis does not require ethical approval. The results of this study will be published in international peer-reviewed journals.

Effectiveness of a large-scale home visiting programme (PIM) on early child development in Brazil: quasi-experimental study nested in a birth cohort

BACKGROUND

A large-scale parenting programme with weekly home visits (Primeira Infância Melhor (PIM)) has been implemented in the south of Brazil for nearly two decades, but lacks evaluation of its effects on early childhood development (ECD). This quasi-experimental study aimed to assess the effects of PIM in real-life settings within a population-based birth cohort study.

METHODS

Data from the 2015 Pelotas Birth Cohort Study and the state programme information system were linked to identify study children who received PIM. Propensity score matching was used to create a comparable control group (using one-to-one matching) to estimate the effect of PIM on ECD measured at age 4 years. First, the impact of any enrolment in PIM was evaluated; then the intervention group was stratified according to whether enrolment occurred during pregnancy or after birth. Double adjustment was applied in linear regression to analyse child development scores, and Poisson regression for delayed development (below the 10th percentile of whole cohort). Effect modification due to family income was explored.

RESULTS

There was no evidence that any enrolment in PIM (601 pairs) by age 4 years was associated with child development. However, PIM starting during pregnancy (estimated for 121 pairs) predicted higher development scores (0.27 SD; 95% CI 0.02 to 0.52), and 71% lower prevalence of delayed development (prevalence ratio=0.29; 95% CI 0.13 to 0.69), compared with the control group. There was strong statistical evidence (p=0.003, test of interaction) that the effect of PIM starting in pregnancy was larger than when starting after birth (480 pairs). The effect of PIM starting during pregnancy was found to be restricted to poorer families.

CONCLUSIONS

In a real-life setting, PIM was effective only when starting during pregnancy and only for poorer families. A higher-quality programme might be more effective with a broader population.