CAPE TOWN - The National Institute for Communicable Diseases (NICD) has noted a sharp increase in influenza-like illness (ILI) and hospitalised cases of pneumonia in the first week of this month.
In a statement, the NICD said it had recorded a steady increase in the number of influenza cases from the week starting August 23, with a sharp increase in the week starting November 1, from ILI and pneumonia surveillance sentinel sites.
“In addition, private laboratories have reported an increase in influenza case detections and the NICD, a division of the National Health Laboratory Service, has received reports of clusters of influenza cases in schools and workplaces,” the NICD said.
Influenza A(H3N2), influenza A(H1N1)pdm09 and influenza B are seasonal influenza virus strains that are common in human populations.
Influenza A(H1N1)pdm09, which is sometimes incorrectly referred to as “swine flu”, has been one of the circulating seasonal influenza strains following its emergence in 2009.
As of the week ending November 7, the total number of influenza cases detected has increased from 68 to 226.
The increase in case numbers has been identified in the provinces where surveillance is conducted - Gauteng, KZN, Mpumalanga, North West and the Western Cape.
To date, the most commonly detected subtype and lineage is influenza B Victoria (38.5%) followed by influenza A (H1N1)pdm09 (23.5%) and influenza A (H3N2) (10.6%).
Even though the detection rates for influenza in NICD surveillance programme exceed previous seasonal thresholds, absolute numbers remain relatively low compared to previous years, possibly as a result of reduced health-seeking behaviour following the Sars-CoV-2 pandemic, the NICD said.
Centre for Respiratory Diseases and Meningitis head Professor Cheryl Cohen said: “The increase in influenza in the summer, which is not the typical time for the influenza season, is likely the result of relaxation of non-pharmaceutical interventions to control Covid-19, combined with an immunity gap due to influenza not circulating for two years (2020 and 2021) in South Africa (as a result of these interventions).”
She stressed that the influenza vaccine remains the primary means for preventing seasonal influenza infection and should ideally be administered before the influenza season from March to April.
“Although the majority of people with influenza will present with mild illness, influenza may cause severe illness, which may require hospitalisation or cause death, especially in individuals who are at risk of getting severe influenza complications,” said medical epidemiologist at the Centre for Respiratory Diseases and Meningitis, Dr Sibongile Walaza.