Student presentations on Disease Control, Epidemiology & Biostatistics took centre stage at the School of Health Systems and Public Health Research Day on 3 July 2025. Master’s students from the University of Pretoria showcased their latest research tackling some of South Africa’s most pressing public health challenges, including drug-resistant tuberculosis, infant growth among HIV-exposed children, hypertension trends in rural communities, vaccine safety monitoring, and respiratory disease surveillance. Their insightful findings highlight the vital role of rigorous research in informing health policies and improving population health outcomes.

Omonwumi Unwegbuna shed light on the prevalence and molecular characteristics of drug-resistant tuberculosis (TB) in Tshwane, Gauteng. Presented as part of her Master’s in Public Health, the research focuses on patients attending government clinics and aims to inform health policy and TB control strategies.

Unwegbuna’s cross-sectional study analysed data from 913 TB patients between January 2021 and December 2022, using advanced molecular testing methods to detect resistance to first-line drugs, isoniazid and rifampicin, as well as second-line treatments. The findings showed that approximately 11% of the patients exhibited resistance to at least one first-line drug, with 24 cases classified as multidrug-resistant TB (MDR-TB). Encouragingly, rates of extensively drug-resistant TB (XDR-TB) were below global averages, and no XDR-TB cases were identified in the study group.

Unwegbuna emphasised the importance of early diagnosis, universal drug susceptibility testing, and treatment adherence to achieve the World Health Organization’s goal of ending the global TB epidemic by 2035. “This study provides crucial data that can help health authorities refine strategies to combat drug-resistant TB in Tshwane,” she said, adding that her findings align with the Sustainable Development Goal 3 for good health and well-being.

Study Explores Effects of HIV Treatment on Infant Growth in Johannesburg

Hlamulani Macebele presented findings from a secondary analysis of the ADVANCE trial, an HIV treatment study conducted in Johannesburg between 2017 and 2023. The study detailed how HIV treatment during pregnancy may influence infant growth during the first 18 months of life.

The study compared the impact of two antiretroviral therapies (ART),  dolutegravir and efavirenz,  on infant growth outcomes. While previous research has linked ART to weight changes in mothers, its effects on infant development remained unclear. Macebele’s study found that although infants in both treatment groups demonstrated healthy weight trajectories, many showed signs of stunted linear growth, with a large proportion falling below the World Health Organization (WHO) third percentile for length.

“These results suggest that stunting remains a concern among HIV-exposed infants, regardless of which ART regimen is used,” said Macebele. “This highlights the need for a more holistic approach to maternal and child health beyond medication alone.”

The study, which included 67 infants, revealed that maternal factors such as Body Mass Index (BMI), delivery method, and age influenced growth outcomes. Caesarean births, for instance, were linked to lower weight-for-age scores, while term deliveries supported healthier growth. Macebele called for continued research into long-term growth outcomes and emphasised the importance of integrated health interventions during and after pregnancy.

Hypertension on the Decline in Rural South Africa, But Rising Obesity Signals New Risks

Continuing with the theme of the session, Disease Control/Epidemiology & Biostatistics, Lucky Mondlane presented on hypertension,  a growing yet often overlooked public health challenge. Mondlane shared findings from his study titled “Trends in Hypertension Prevalence among Adults Aged 40 and Above in Agincourt, South Africa, from 2014 to 2022,” which examined data collected over three waves of the Health and Aging in Africa: A Longitudinal Study of an INDEPTH Community in South Africa (HAALSI) study.

The study, involving over 3,700 participants, revealed a significant decline in hypertension prevalence from 58% to 30% over eight years in the Agincourt subdistrict of Mpumalanga. "This trend may reflect improved awareness, screening, and management efforts in the community," Mondlane explained. However, the study also reported rising rates of overweight and diabetes - known risk factors for hypertension. Using generalised estimating equations, Mondlane and his team identified high BMI, alcohol use, and lack of formal education as major contributors to elevated blood pressure.

“While the reduction in hypertension is promising, the increase in obesity and diabetes is worrying and calls for urgent lifestyle interventions,” he added. The findings reinforce the goals of South Africa’s national strategy on non-communicable diseases and highlight the need to strengthen primary healthcare and prevention efforts in rural communities.

Decade-Long Surveillance Highlights Success of Hib Vaccine—but Non-Typeable and Unknown Strains Remain a Threat

Ayanda Majenge presented findings from her 12-year surveillance study conducted during her time at the National Institute for Communicable Diseases (NICD), titled "The Epidemiology of Invasive Haemophilus Influenzae Disease in All Ages in South Africa from 2010 to 2022."

Haemophilus influenzae is a gram-negative bacterium responsible for severe respiratory infections and meningitis. Majenge’s study evaluated over 4,000 laboratory-confirmed cases from national surveillance data to understand trends post-introduction of the fourth Hib vaccine booster dose in 2009.

“We saw a clear decline in the incidence of Haemophilus influenzae type B (Hib) across all age groups following the rollout of the booster,” said Majenge. “This supports the effectiveness of the conjugate vaccine program.”

However, she emphasised that non-typeable Haemophilus influenzae has now emerged as the most prevalent strain across all age groups, particularly among infants and adults with comorbidities. “Non-typeable strains were associated with higher mortality, especially among those under one year and those presenting late to hospitals,” she noted.

She concluded: “Non-typeable Haemophilus influenzae is now the most common strain in South Africa. While Hib and other serotypes remain well-controlled thanks to the national immunisation programme, continuous surveillance and improved laboratory reporting are essential to stay ahead of emerging threats.”

South Africa’s vaccine safety study flags underreporting but confirms global signal alignment

Chenoa Sankar presented findings from her master’s research that evaluated adverse events following immunisation (AEFI) reported to South Africa’s National Immunisation Safety Expert Committee (NISEC) between 2021 and 2022. Her study is one of the first from a lower-middle-income country to apply signal detection methods using spontaneous vaccine safety data in the wake of the COVID-19 rollout.

“Adverse events following immunisation are defined as any untoward medical occurrence after vaccination - whether or not it’s caused by the vaccine,” she said. “These can include abnormal lab findings, symptoms, or diseases. Our aim was to determine whether AEFI signals in South Africa aligned with what was being reported internationally, particularly for COVID-19 vaccines.”

Her study used Bayesian statistical approaches - including the WHO-endorsed Bayesian Confidence Propagation Neural Network - to detect signals of disproportionate reporting. “This method allows us to quantify whether there’s a statistical dependency between a vaccine and an adverse event,” Sankar explained. “If the information component is above zero, it suggests a real signal worth investigating.”

The findings showed that the Johnson & Johnson vaccine (AD26) had a significantly higher AEFI reporting rate -18.1 per 100,000 doses - compared to Pfizer’s Comirnaty (7.9 per 100,000). Notably, the top ten adverse events reported for AD26 all registered as significant signals. For Comirnaty, fewer signals were detected, but dyspnea, chest pain, dizziness, and fatigue emerged in the adjusted dataset.

“Our results showed strong alignment with global data, but they also revealed key gaps in our surveillance system,” Sankar said. “We saw evidence of underreporting, and a phenomenon called ‘masking,’ where a flood of COVID-related reports buried other signals. We had to create stabilised datasets to offset this background noise.”

Both arms of the study - published in Vaccines and Drug Safety - call for improvements to the national surveillance system. “This research demonstrates the capability of local systems to contribute meaningfully to global pharmacovigilance,” she concluded. “But it also highlights the need to invest in tools, training, and infrastructure to reduce underreporting and strengthen safety signal detection.”