Why Is Influenza Still a Concern in South Africa?
Influenza, commonly known as the flu, is a highly contagious respiratory illness caused by influenza viruses that primarily affect the nose, throat, and sometimes the lungs. Its severity can vary from mild symptoms to life-threatening complications, especially for vulnerable populations such as the elderly, young children, and individuals with chronic health conditions. Every year, the flu causes widespread illness and can lead to significant public health challenges.
In South Africa, flu season peaks during the winter months, impacting communities and healthcare systems. As the virus continues to mutate, the need for updated vaccines becomes critical to protect against new strains. The flu’s ability to change makes it essential to have an adaptive approach to vaccination and prevention.
To effectively manage flu outbreaks, South Africa relies on robust influenza surveillance programmes. Coordinated by the National Institute for Communicable Diseases (NICD), these sentinel surveillance systems track flu activity across diverse healthcare settings. They help monitor trends, identify emerging strains, and inform vaccine composition recommendations. Data collected from these surveillance efforts is shared with the World Health Organization (WHO), contributing to global strategies for flu control and prevention.
The following report examines the prevalence of influenza-related illnesses among South African populations during the 2024 flu season, highlighting key trends and surveillance data.
Materials and Methods
Influenza surveillance in South Africa is conducted through three sentinel programmes coordinated by the Centre for Respiratory Diseases and Meningitis (CRDM) at the National Institute for Communicable Diseases (NICD). These programs include Viral Watch surveillance at private general practitioners, systematic influenza-like illness (ILI) surveillance at public health clinics, and national pneumonia surveillance in public health hospitals.
Participants who met case definitions were consented and enrolled. Demographic and clinical data were gathered through patient interviews and medical record reviews. Respiratory specimens, including combined oropharyngeal and nasopharyngeal/nasal swabs, were collected and tested for influenza using reverse transcription real-time PCR (rRT-PCR).
Results
From January 1 to December 29, 2024, a total of 7,690 individuals were enrolled across the three influenza surveillance programmes in South Africa, with respiratory specimens collected and tested for influenza. Of these, 997 individuals tested positive for influenza, resulting in an overall detection rate of 13.0%. Influenza cases were detected consistently throughout the year, with notable peaks during the flu season.
For the 96.8% of cases (965/997) where a subtype/lineage could be determined, the majority of infections were caused by influenza A(H1N1)pdm09, which accounted for 60.8% of single infections.
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