Publications by authors named "Walaza S"
Background: Seasonal influenza illness and acute respiratory infections can impose a substantial economic burden in low- and middle-income countries (LMICs). We assessed the cost of influenza illness and acute respiratory infections across household income strata.
Methods: We conducted a secondary analysis of data from a prior systematic review of costs of influenza and other respiratory illnesses in LMICs and contacted authors to obtain data on cost of illness (COI) for laboratory-confirmed influenza-like illness and acute respiratory infection.
Background: Group B Streptococcus (GBS) is a leading cause of neonatal meningitis and sepsis and an important cause of disease in adults. Capsular polysaccharide and protein-based GBS vaccines are currently under development.
Methods: Through national laboratory-based surveillance, invasive GBS isolates were collected from patients of all ages between 2019 and 2020.
Home-Based Testing as an Approach to Estimate Influenza Vaccine Effectiveness in South Africa, 2021-2022-A Pilot Study.
Influenza Other Respir Viruses
December 2024
Article Synopsis
- A study in South Africa tested the feasibility of home-based influenza testing for individuals showing respiratory symptoms, collecting swabs and vaccination data from participants aged 18 and older.
- Out of 1456 samples, 5% tested positive for influenza, while 27% were positive for SARS-CoV-2; the overall vaccine effectiveness for influenza was determined to be 26%.
- The service was well-received, with 97% of participants willing to use it again, suggesting that home swabbing could be a practical option for respiratory surveillance in the future.*
Background: Approaches for determining whether influenza vaccination prevents infection, attenuates illness, or both, are important for developing improved vaccines. We estimated influenza infection incidence, and evaluated symptom ascertainment methodologies in children to inform future vaccine trial design.
Methods: We conducted a prospective cohort study among children aged 6-23 months from May-October 2022.
Article Synopsis
- Identifying risk factors for RSV-associated severe acute respiratory illness (SARI) is crucial for improving vaccine strategies and interventions.
- Surveillance data from South Africa (2012-2018) showed that RSV was more common in SARI cases (15%) than in influenza-like illness (ILI) cases (6%), highlighting the importance of targeted research.
- Key risk factors for SARI included very young age (under 2 months), malnutrition, prematurity, living with HIV for children, and older age, prolonged symptoms, underlying illness, and living with HIV for adults, suggesting the need for focused prevention efforts in these vulnerable groups.
Article Synopsis
- Invasive pneumococcal disease (IPD) remains a serious global issue, particularly concerning non-vaccine serotypes, even after the introduction of pneumococcal conjugate vaccines (PCV) in South Africa.
- The study analyzed over 3,000 IPD genomes from children between 2005-2020, observing a drop in incidence for vaccine-type bacteria in the late-PCV13 period, but some continued to pose a threat.
- Notably, non-vaccine serotypes showed rising drug resistance and lineage diversity, indicating the need for ongoing genomic surveillance to inform health policies and future vaccine developments.
Article Synopsis
- The study evaluated the effectiveness of two COVID-19 vaccines (Pfizer BNT162b2 and Johnson & Johnson Ad26.COV2.S) in preventing hospitalizations in South African adults during different SARS-CoV-2 variants.
- It included 925 cases (hospitalized) and 1890 controls (not hospitalized), analyzing their vaccination status and disease outcomes from June 2021 to March 2022.
- Results showed that BNT162b2 had high effectiveness against hospitalizations during the Delta variant wave, particularly in older and HIV-uninfected adults, while the effectiveness of Ad26.COV2.S was inconclusive.
Background: Comparisons of the characteristics of individuals hospitalised with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) or seasonal influenza in low-to middle-income countries with high human immunodeficiency virus (HIV) prevalence are limited.
Objectives: Determine the epidemiological differences with those hospitalised with influenza or SARS-CoV-2 infection.
Method: We investigated hospitalised individuals ≥18 years of age testing positive for seasonal influenza (2016-2019) or SARS-CoV-2 (2020-2021).
There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced widespread SARS-CoV-2 infection before vaccine availability. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa, in an observational cohort study of >2 million adults during 2020-2022. We described SARS-CoV-2 testing, COVID-19 outcomes, and vaccine uptake over time.
View Article and Find Full Text PDFArticle Synopsis
- Invasive meningococcal isolates in South Africa have shown a consistent presence of serogroups B, C, W, and Y between 2016-2021, with an intermediate penicillin resistance rate of 16%.
- A total of 585 invasive meningococcal disease cases were monitored, with phenotypic and genomic analyses revealing key serogroups and clonal complexes.
- The increased penicillin intermediate resistance was linked to specific penA gene mosaics, indicating a concerning rise in antibiotic resistance among these bacteria compared to prior years.
Article Synopsis
- - The study aimed to identify risk factors for severe COVID-19 hospitalization among children aged 18 and younger by analyzing data from surveillance sites between April 2020 and March 2022
- - Among 4688 participants, certain risk factors were found: children under 6 months old, those with underlying medical conditions, infections with specific COVID-19 variants, and co-infection with respiratory syncytial virus (RSV) were more likely to be hospitalized
- - The findings highlight the importance of age and underlying health issues in assessing the risk of severe respiratory illnesses due to COVID-19 in children, suggesting that ongoing surveillance can effectively monitor these risks.
Background: There are few data on the real-world effectiveness of COVID-19 vaccines and boosting in Africa, which experienced high levels of SARS-CoV-2 infection in a mostly vaccine-naïve population, and has limited vaccine coverage and competing health service priorities. We assessed the association between vaccination and severe COVID-19 in the Western Cape, South Africa.
Methods: We performed an observational cohort study of >2 million adults during 2020-2022.
Article Synopsis
- Pertussis is a growing public health issue in South Africa, with a rise in cases reported in recent years.
- Whole genome sequencing of 32 isolates from 2015 to 2019 revealed that all were sequence type 2, with the dominant genotype being 3122, and no significant mutations in vaccine antigen genes.
- The increase in pertussis cases is likely linked to factors like the cyclical patterns of the disease and gaps in population immunity rather than genetic changes in the bacteria.
Background: The South African government employed various nonpharmaceutical interventions (NPIs) to reduce the spread of SARS-CoV-2. Surveillance data from South Africa indicates reduced circulation of respiratory syncytial virus (RSV) throughout the 2020-2021 seasons. Here, we use a mechanistic transmission model to project the rebound of RSV in the two subsequent seasons.
View Article and Find Full Text PDFWe enrolled 1323 hospitalized infants aged <1 year in 2016-2018, and examined the association between HIV status and in-hospital mortality. After controlling for confounders, HIV-exposed uninfected infants did not have an increased risk of mortality, whereas infants living with HIV had 4 times greater risk compared with HIV-uninfected infants.
View Article and Find Full Text PDFObjectives: This study analyzed the association of TNFAIP3-interacting protein 1 (TNIP1) polymorphisms with the symptomatic human respiratory syncytial virus (HRSV) infection and bronchiolitis in infants.
Methods: A case-control study was conducted involving 129 hospitalized infants with symptomatic HRSV infection (case group) and 161 healthy infants (control group) in South Africa (2016-2018). Six TNIP1 polymorphisms (rs869976, rs4958881, rs73272842, rs3792783, rs17728338, and rs999011) were genotyped.
Article Synopsis
- South Africa has the highest COVID-19 cases in Africa, and there's a need for data on public knowledge, vaccine intentions, and trusted information sources about the virus.
- The study surveyed 5,799 primary caregivers in three communities during the second wave of COVID-19, revealing that most respondents understood how the virus spreads and had intentions to get vaccinated, particularly among those over 64 years old.
- The findings suggest that public health campaigns should focus on socio-economic factors and reliable information sources, such as television, to improve vaccination rates and responses to future health crises.
Healthcare utilization surveys contextualize facility-based surveillance data for burden estimates. We describe healthcare utilization in the catchment areas for sentinel site healthcare facilities during the first year of the COVID-19 pandemic. We conducted a cross-sectional healthcare utilization survey in households in three communities from three provinces (KwaZulu-Natal, Western Cape and North West).
View Article and Find Full Text PDFArticle Synopsis
- A study analyzed COVID-19 severity in hospitalized children across nine countries, focusing on the impact of different SARS-CoV-2 variants over time.
- It found that children younger than 5 years showed a decrease in ICU admissions during the Omicron wave compared to the earlier variants, but ventilatory support needs remained unchanged.
- In older children (5 to <18 years), there was a significant decrease in ICU admissions, ventilatory support, and oxygen therapy requirements as new variants emerged.
Background: Households are an important location for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) transmission, especially during periods when travel and work was restricted to essential services. We aimed to assess the association of close-range contact patterns with SARS-CoV-2 transmission.
Methods: We deployed proximity sensors for two weeks to measure face-to-face interactions between household members after SARS-CoV-2 was identified in the household, in South Africa, 2020-2021.
Objectives: The detection of respiratory syncytial virus (RSV) in upper airway samples does not necessarily infer causality of illness. We aimed to calculate the attributable fraction (AF) of RSV in clinical syndromes across age groups.
Methods: Using unconditional logistic regression models, we estimated the AF of RSV-associated influenza-like illness (ILI) and severe acute respiratory illness (SARI) cases by comparing RSV detection prevalence among ILI and SARI cases to those of healthy controls in South Africa, 2012-2016.
Background: Data on the economic burden of RSV-associated illness will inform decisions on the programmatic implementation of maternal vaccines and monoclonal antibodies. We estimated the cost of RSV-associated illness in fine age bands to allow more accurate cost-effectiveness models to account for a limited duration of protection conferred by short- or long-acting interventions.
Methods: We conducted a costing study at sentinel sites across South Africa to estimate out-of-pocket and indirect costs for RSV-associated mild and severe illness.
Background: Vaccines and monoclonal antibodies to protect the very young infant against the respiratory syncytial virus (RSV)-associated illness are effective for limited time periods. We aimed to estimate age-specific burden to guide implementation strategies and cost-effectiveness analyses.
Methods: We combined case-based surveillance and ecological data to generate a national estimate of the burden of RSV-associated acute respiratory illness (ARI) and severe acute respiratory illness (SARI) in South African children aged < 5 years (2011-2016), including adjustment for attributable fraction.
Article Synopsis
- The risk of invasive pneumococcal disease (IPD) increases with age in older adults, but their response to pneumococcal vaccinations diminishes over time.
- A study was conducted using data from adults aged 55 and older to evaluate the best age for a single-dose pneumococcal vaccine based on demographics, vaccine efficacy, and waning effectiveness.
- Results suggest that administering the vaccine at 55 years old in Brazil, Malawi, and South Africa, and at 70 years in England, could effectively reduce IPD cases, highlighting the need for earlier vaccination in low/middle-income countries compared to high-income countries.