About
217
Publications
22,997
Reads
How we measure 'reads'
A 'read' is counted each time someone views a publication summary (such as the title, abstract, and list of authors), clicks on a figure, or views or downloads the full-text. Learn more
9,012
Citations
Introduction
Publications
Publications (217)
Background
This study reviews the impact of eligibility policies in the early rollout of the COVID-19 vaccine on coverage and probable outcomes, with a focus on New York City (NYC).
Methods
A retrospective ecological study was conducted assessing age 65+, area-level income, vaccination coverage, and COVID-19 mortality rates, using linked Census Bu...
Background
Respiratory Syncytial Virus (RSV) is a major health concern, particularly for infants. In France, Nirsevimab, a long‐acting monoclonal antibody to prevent RSV‐associated lower respiratory tract infections (LRTI) was available from September 2023. We described RSV‐associated LRTI hospitalisations during the 2023–2024 season among infants...
The COVID-19 pandemic and related preventive measures reduced influenza virus circulation, notably causing the disappearance of the B/Yamagata lineage of influenza viruses. In this Perspective, we discuss the implications that this development may have for global influenza epidemiology, and the adjustments that may need to be implemented concerning...
Background
No data are available regarding the interplay and clinical manifestations of respiratory syncytial virus (RSV) and severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) coinfection in African children. We compared clinical characteristics and outcomes between RSV-only, SARS-CoV-2–only and RSV/SARS-CoV-2 coinfection lower respirato...
Brand serves as the foundation for the entire experience an organisation can
deliver across communications, products and services, environments and people.
Establishing a strong brand identity is crucial for research institutions to stand
out and fulfill their missions effectively. Wits VIDA (previously RMPRU) leadership understood the importance...
SARS-CoV-2 cell-mediated immunity remains understudied during pregnancy in unvaccinated Black African women living with HIV (WLWH) from low- and middle-income countries. We investigated SARS-CoV-2-specific T-cell responses 1 month following infection in 24 HIV-uninfected women and 15 WLWH at any stage during pregnancy or postpartum. The full-length...
Streptococcus pneumoniae remains a leading cause of morbidity and mortality in children <5-years-old in sub-Saharan Africa. Monitoring serotype-specific nasopharyngeal colonisation can serve as a proxy to evaluate the effect of vaccination against vaccine-serotype (VT) disease. We evaluated the impact of 13-valent pneumococcal conjugate vaccine (PC...
Background
Hypoxemia predicts mortality at all levels of care, and appropriate management can reduce preventable deaths. However, pulse oximetry and oxygen therapy remain inaccessible in many primary care health facilities. We aimed to develop and validate a simple risk score comprising commonly evaluated clinical features to predict hypoxemia in 2...
Background
Several influenza vaccine candidates aim to elicit antibodies against the conserved hemagglutinin stalk domain. Understanding the protective mechanism of these antibodies, which mediate broad neutralization and Fc-mediated functions, following seasonal vaccination is critical.
Methods
Plasma samples were obtained from a subset of pregna...
Early after the start of the COVID-19 pandemic, the detection of influenza B/Yamagata cases decreased globally. Given the potential public health implications of this decline, in this Review, we systematically analysed data on influenza B/Yamagata virus circulation (for 2020–23) from multiple complementary sources of information. We identified rele...
Background
Respiratory syncytial virus (RSV) poses a substantial threat to infants, often leading to challenges in hospital capacity. With recent pharmaceutical developments to be used during the prenatal and perinatal periods aimed at decreasing the RSV burden, there is a pressing need to identify infants at risk of severe disease. We aimed to str...
Introduction
COVID-19 was an unprecedented challenge worldwide; however, disease epidemiology has evolved, and COVID-19 no longer constitutes a public health emergency of international concern. Nonetheless, COVID-19 remains a global threat and uncertainties remain, including definition of the end of the pandemic and transition to endemicity, and un...
Respiratory syncytial virus (RSV) is a leading cause of acute lower respiratory tract infection in young children and the second leading cause of infant death worldwide. While global circulation has been extensively studied for respiratory viruses such as seasonal influenza, and more recently also in great detail for SARS-CoV-2, a lack of global mu...
This study reviews the impact of eligibility policies in the early rollout of the COVID-19 vaccine on coverage and probable outcomes, with a focus on New York City. We conducted a retrospective ecological study assessing age 65+, area-level income, vaccination coverage, and COVID-19 mortality rates, using linked Census Bureau data and New York City...
Health care workers (HCWs) are primary health providers therefore ensuring their protection and recovery from Covid-19 is of high interest. We investigated post-acute sequelae of SARS-CoV-2 infection (PASC) in HCWs who had previously been infected with SARS-CoV-2. Overall, 68 HCWs were classified as PASC according to duration in days of persisting...
Background: Seroepidemiology studies are useful for quantifying the magnitude of past infections and estimating the extent of population-based immunity to inform risk mitigation strategies for the future. We report on the only national population-based survey of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) immunoglobulin G (IgG) ser...
Purpose of review
This review covers updated perspectives on different aspects of pneumococcal community-acquired pneumonia (pCAP), including the epidemiology, clinical presentation, risk factors, antibiotic treatment, and existing preventive strategies in older adults.
Recent findings
pCAP remains the most prevalent condition among lower respirat...
In July 2023, the Center of Excellence in Respiratory Pathogens organized a two-day workshop on infectious diseases modelling and the lessons learnt from the Covid-19 pandemic. This report summarizes the rich discussions that occurred during the workshop.
The workshop participants discussed multisource data integration and highlighted the benefits...
HIV-exposed uninfected infants (HEU) have higher infectious morbidity than HIV-unexposed infants (HUU). HEU have multiple immune defects of unknown origin. We hypothesized that HEU have higher regulatory T cells (Treg) than HUU, which may dampen their immune defenses against pathogens. We compared 25 Treg subsets between HEU and HUU and sought the...
Rationale:
In the upper respiratory tract replicating (culturable) SARS-CoV-2 is recoverable for ~ 4 to 8 days after symptom onset, however, there is paucity of data about the frequency or duration of replicating virus in the lower respiratory tract (i.e. the human lung).
Objectives:
We undertook lung tissue sampling (needle biopsy), shortly aft...
Pertussis remains a public health concern in South Africa, with an increase in reported cases and outbreaks in recent years. Whole genome sequencing was performed on 32 Bordetella pertussis isolates sourced from three different surveillance programmes in South Africa between 2015 and 2019. Genome sequences were characterized using multilocus sequen...
SARS-CoV-2 cell-mediated immunity remains understudied during pregnancy in unvaccinated black African women living with HIV (WLWH) from low- and middle-income countries. We investigated SARS-CoV-2-specific T-cell responses one-month post infection in 24 HIV-uninfected women and 15 WLWH at any stage during pregnancy or postpartum. The full-length sp...
Pneumonia is a major cause of death among adults living with HIV in South Africa, but the etiology of many cases remains unknown. This study evaluated the utility of a nanofluidic qPCR assay to detect and serotype Streptococcus pneumoniae in urine samples from patients hospitalized with community-acquired pneumonia (CAP). The nanofluidic qPCR assay...
Background
Deployment of non-pharmaceutical interventions such as face masking and physical distancing during the COVID-19 pandemic could have altered the transmission dynamics and carriage of respiratory organisms. We evaluated colonisation with Streptococcus pneumoniae and other upper respiratory tract bacterial colonisers before and during the C...
Vaccination during pregnancy with tetanus-diphtheria-acellular pertussis (Tdap) vaccine is recommended to protect the young infants against pertussis. There is a paucity of data on immune responses to Tdap in pregnant women living with HIV (PWLWH), and its impact on the protection of their infants has not been described.
In an open label phase IV c...
Introduction
Early after the start of the COVID-19 pandemic, a major drop in the number of influenza B/Yamagata detections was observed globally. Given the potential public health implications, particularly with regards to influenza vaccination, we conducted a systematic review of influenza B/Yamagata virus circulation data from multiple complement...
The pathogenesis of coronavirus disease 2019 (COVID-19) pneumonia remains poorly understood. The urine proteome of hospitalized patients with severe COVID-19 pneumonia, compared with severe non-COVID-19 pneumonia controls, was distinct and associated with lower abundance of several host proteins. Protein-specific machine learning analysis outlined...
Background:
The Global Influenza Hospital Surveillance Network (GIHSN) has since 2012 provided patient-level data on severe influenza-like illnesses from over 100 participating clinical sites worldwide based on a core protocol and consistent case definitions. To our knowledge, this is the first study to analyze multiple years of global, patient-le...
Despite the success of COVID-19 vaccines, severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) variants of concern have emerged that can cause breakthrough infections. Although protection against severe disease has been largely preserved, the immunological mediators of protection in humans remain undefined. We performed a substudy on the Ch...
Background:
Literature is limited on the impact of patient vaccination on the risk of hospital-acquired influenza (HAI). This test negative case-control study nested in a surveillance program aimed at evaluating the effectiveness of influenza vaccination in reducing the risk of HAI in hospitalized patients during 15 influenza seasons (2004-05 to 2...
Pneumococcal conjugate vaccines (PCVs) provide protection against vaccine-type pneumococcal disease in both children and adults. Growing evidence suggests that PCVs also reduce pneumonia and lower respiratory tract infections (LRTIs) more broadly, including protecting against viral-associated respiratory diseases. In this short narrative review, we...
Background
Respiratory syncytial virus (RSV) is the most common cause of hospitalisation for lower respiratory tract infection (LRTI) in children. RSV LRTI during early childhood may increase susceptibility to recurrent wheezing and asthma.
Research question
The aim of this study was to describe the pulmonary sequelae at 1 and 2 years of age follo...
Background
The Global Influenza Hospital Surveillance Network (GIHSN) was established in 2012 to conduct coordinated worldwide influenza surveillance. Here we describe underlying comorbidities, symptoms, and outcomes in hospitalized patients with influenza.
Methods
Between November/2018 and October/2019, GIHSN included 19 sites in 18 countries usi...
Background:
Non-pharmaceutical interventions affected the circulation of and illness due to endemic respiratory pathogens during the COVID-19 pandemic. We investigated the incidence of admissions to hospital for overall and specific pathogen-associated lower respiratory tract infection (LRTI) during the COVID-19 pandemic compared with incidence in...
Background:
Pneumococcal Conjugate Vaccines (PCVs) reduce pneumococcal-associated disease by reducing vaccine-serotype (VT) acquisition in vaccinated children, thereby interrupting VT transmission. The 7-valent-PCV was introduced in the South African immunisation program since 2009 (13-valent-PCV since 2011) using a 2+1 schedule (6-, 14- and 40-we...
Sensitive tools for detecting concurrent colonizing pneumococcal serotypes are needed for detailed evaluation of the direct and indirect impact of routine pneumococcal conjugate vaccine (PCV) immunization. A high-throughput quantitative nanofluidic real-time PCR (Standard BioTools ‘Fluidigm’) reaction-set was developed to detect and quantify 92 pne...
Rationale
In the upper respiratory tract replicating (culturable) SARS-CoV-2 is recoverable for ∼ 4 to 8 days after symptom onset, however, there is paucity of data about the frequency or duration of replicating virus in the lower respiratory tract (i.e. the human lung).
Objectives
We undertook lung tissue sampling (needle biopsy), shortly after d...
Background:
Nirsevimab is an extended half-life monoclonal antibody to the respiratory syncytial virus (RSV) fusion protein that has been developed to protect infants for an entire RSV season. Previous studies have shown that the nirsevimab binding site is highly conserved. However, investigations of the geotemporal evolution of potential escape v...
Objectives:
We determined pulse oximetry benefit in pediatric pneumonia mortality-risk stratification and chest indrawing pneumonia in-hospital mortality risk factors.
Methods:
We report characteristics and in-hospital pneumonia-related mortality of children 2-59-months-old included in the Pneumonia Research Partnership to Assess WHO Recommendat...
Introduction
Despite a growing body of research on the risks of SARS-CoV-2 infection during pregnancy, there is continued controversy given heterogeneity in the quality and design of published studies.
Methods
We screened ongoing studies in our sequential, prospective meta-analysis. We pooled individual participant data to estimate the absolute an...
Quantitative real-time PCR (qPCR) methods are now routinely used and have advanced to allow for high-throughput amplification of multiple targets in a single qPCR run. Where algorithms and comparisons are used to interpret the results of different assay-sets (primers and probe for one target), or multiple assay-sets in a run (a reaction-set), betwe...
Objectives:
This study aimed to investigate severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2)-specific T-cell responses 14 days after single-dose ChAdOx1 nCoV-19 (AZD1222) vaccination in black Africans with and without HIV in South Africa, as well as determine the effect of AZD1222 vaccination on cell-mediated immune responses in people...
Background:
The existing World Health Organization (WHO) pneumonia case management guidelines rely on clinical symptoms and signs for identifying, classifying, and treating pneumonia in children up to 5 years old. We aimed to collate an individual patient-level data set from large, high-quality pre-existing studies on pneumonia in children to iden...
Background:
SARS-CoV-2 infection in pregnant women has been associated with severe illness in the women and higher rates of premature delivery. There is, however, paucity of data on the impact of the timing of SARS-CoV-2 infection and on symptomatic or asymptomatic infections on birth outcomes. Data from low-middle income settings is also lacking....
Background: Sensitive tools for detecting concurrent colonizing pneumococcal serotypes are needed for detailed evaluation of the direct and indirect impact of routine pneumococcal conjugate vaccine (PCV) immunization. Method: A high-throughput quantitative nanofluidic real-time PCR (Fluidigm) reaction-set was developed to detect and quantify 92 pne...
Background
Influenza disease data remain scarce in middle and lower-income countries. We used data from the Global Influenza Hospital Surveillance Network (GIHSN), a prospective multi-country surveillance system from 2012-2019, to assess differences in the epidemiology and severity of influenza hospitalizations by country income level.
Methods
We c...
Introduction
The high burden of respiratory syncytial virus (RSV) infection in young children disproportionately occurs in low- and middle-income countries (LMICs). The PROUD (Preventing RespiratOry syncytial virUs in unDerdeveloped countries) Taskforce of 24 RSV worldwide experts assessed key needs for RSV prevention in LMICs, including vaccine an...
Objective Severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) infection during pregnancy has been associated with poor pregnancy outcomes. There is, however, not much information on the impact of the timing of SARS-CoV-2 infection on pregnancy outcomes, and studies from low-middle income settings are also scarce.
Study Design We conducted...
Using hospital surveillance data, we estimated hMPV hospitalization incidence by age and HIV-exposure status. hMPV-associated hospitalization incidence was highest in <1-year children. Incidence rate ratios of HIV-exposed over unexposed children were 1.5 (95%CI 0.9-2.4) for <6-month children, 1.4 (95%CI 0.7-2.4) for 6-11-month children and 0.9 (95%...
Influenza vaccination of pregnant women reduces influenza-associated illness in the women and their infants, but effectiveness estimates against influenza-associated hospitalization are limited and are lacking from settings with high maternal HIV-infection prevalence. We assessed the effect of maternal vaccination in HIV-uninfected women and women...
Host genetic factors are known to modify the susceptibility, severity, and outcomes of COVID-19 and vary across populations. However, continental Africans are yet to be adequately represented in such studies despite the importance of genetic factors in understanding Africa’s response to the pandemic. We describe the development of a research resour...
To encourage COVID-19 vaccination, governments have offered a wide range of incentives to their populations ranging from cash to cows. Often these programs were rolled out at scale before assessing potential effectiveness. To inform future policy, we conducted a narrative review to understand the evidence base informing these programs and the exten...
HIV-exposed uninfected infants (HEU) are highly vulnerable to infections in the first 6 months of life, and this vulnerability decreases to the age of 24 months. Because the microbiome plays a critical role in the education of the infant immune system, which protects them against infections, we characterized the gut microbiomes of HEU and HIV-unexp...
In pregnant women antibodies against severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike protein cross the placenta and can be detected in cord-blood at the time of delivery. We measured SARS-CoV-2 full-length anti-spike IgG in blood samples collected from women living with HIV (WLWHIV) and without HIV when presenting for labour, and...
Respiratory syncytial virus is the second most common cause of infant mortality and a major cause of morbidity and mortality in older adults (aged >60 years). Efforts to develop a respiratory syncytial virus vaccine or immunoprophylaxis remain highly active. 33 respiratory syncytial virus prevention candidates are in clinical development using six...
Objective
This sequential, prospective meta-analysis (sPMA) sought to identify risk factors among pregnant and postpartum women with COVID-19 for adverse outcomes related to: disease severity, maternal morbidities, neonatal mortality and morbidity, adverse birth outcomes.
Data sources
We prospectively invited study investigators to join the sPMA v...
Background : A potential explanation for the fact that the high rate of infection of SARS-CoV-2 in South Africa did not translate into high rates of severe illness and death may be the presence of cross-reactive immunity induced by common cold coronaviruses (CCoV).
Methods : We used SARS-CoV-2 peptide pools and whole virus antigen to stimulate peri...
Coronavirus disease 2019 (COVID-19) which is caused by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) has been associated with severe illness in pregnant women. Furthermore, COVID-19 during pregnancy is associated with adverse foetal outcomes, including preterm labour. Pregnant women were largely excluded from initial clinical tri...
Influenza virus hemagglutinin (HA) stalk-specific antibodies have been shown to potently induce Fc-mediated effector functions which are important in protection from disease. In placebo-controlled maternal influenza (MatFlu) vaccination trials of pregnant women living with or without HIV, reduced risk of influenza illness was associated with high H...
Introduction
Existing risk assessment tools to identify children at risk of hospitalised pneumonia-related mortality have shown suboptimal discriminatory value during external validation. Our objective was to derive and validate a novel risk assessment tool to identify children aged 2–59 months at risk of hospitalised pneumonia-related mortality ac...
Purpose: Current quantitative real-time Polymerase Chain Reaction (qPCR) methods are unable to distinguish serotypes 6A from 6B, 18C from 18A/B and 22F from 22A. We established a nanofluidic real-time PCR (Fluidigm) to distinguish between these individual serotypes by including Dual Priming Oligonucleotide (DPO) primers, a Locked Nucleic Acid (LNA)...
We investigated Omicron infections among healthcare workers (HCW) presenting with symptoms of SARS-CoV-2 infection and evaluated the protective effect of vaccination or prior infection.
Between 24 th November and 31 st December 2021, HCW in Johannesburg, South Africa, were tested for SARS-CoV-2 infection by Nucleic Acid Amplification Test (NAAT). B...
Comparisons of histopathological features and microbiological findings between decedents with respiratory symptoms due to SARS-CoV-2 infection or other causes, in settings with high prevalence of HIV and Mycobacterium tuberculosis (MTB) infections have not been reported. Deaths associated with a positive ante-mortem SARS-CoV-2 PCR test and/or respi...
On the 24th November 2021 the sequence of a new SARS CoV-2 viral isolate Omicron-B.1.1.529 was announced, containing far more mutations in Spike (S) than previously reported variants. Neutralization titres of Omicron by sera from vaccinees and convalescent subjects infected with early pandemic as well as Alpha, Beta, Gamma, Delta are substantially...
Current real-time high-throughput Polymerase Chain Reaction (qPCR) methods do not distinguish serotypes 6A from 6B, 18C from 18A/B and 22F from 22A. We established a nanofluidic real-time PCR (Fluidigm) for serotyping that included Dual-Priming-Oligonucleotides (DPO), a Locked-Nucleic-Acid (LNA) probe and TaqMan assay-sets for high-throughput serot...
Objective: Evaluate the impact of the timing of SARS-CoV-2 infection on pregnancy outcomes in a low-middle income setting. Design: two parallel, observational studies. Setting and population: pregnant women or women presenting for labour, enrolled between April-September 2020, in South Africa. Methods: i) longitudinal follow-up study of symptomatic...
We compared plasma and dried blood spots for detection of SARS-CoV-2 IgG antibodies. There was a good correlation between IgG values measured by both sampling methods, r = 0.935 and 0.965 for Receptor Binding Domain and full-length spike protein of SARS-CoV-2. Bland-Altman assessment showed good agreement between two sampling methods. Dried blood s...
Respiratory syncytial virus (RSV)—the most common viral cause of bronchiolitis—is a significant cause of serious illness among young children between the ages of 0–5 years and is especially concerning in the first year of life. Globally, RSV is a common cause of childhood acute lower respiratory illness (ALRI) and a major cause of hospital admissio...
Background
Existing scores to identify children at risk of hospitalized pneumonia-related mortality lack broad external validation. Our objective was to externally validate three such risk scores.
Methods
We applied the Respiratory Index of Severity in Children (RISC) for HIV-negative children, the RISC-Malawi, and the Pneumonia Etiology Research...
Background : A potential explanation for the fact that the high rate of infection of SARS-CoV-2 in South Africa did not translate into high rates of severe illness and death may be the presence of cross-reactive immunity induced by common cold coronaviruses (CCoV).
Methods : We used SARS-CoV-2 peptide pools and whole virus antigen to stimulate peri...