Abstract
ObjectivesInfluenza vaccine effectiveness (VE) and coverage data for sub-Saharan Africa are scarce. Using a test-negative case–control design, we estimated influenza VE annually among individuals with influenza-like illness presenting to an outpatient sentinel surveillance programme in South Africa from 2010 to 2013. A knowledge, attitudes and practices (KAP) influenza vaccine survey of programme clinicians was conducted in 2013.SampleIn total, 9420 patients were enrolled in surveillance of whom 5344 (56.7%) were included in the VE analysis: 2678 (50.1%) were classified as controls (influenza test-negative) and 2666 (49.9%) as cases (influenza test-positive).ResultsMean annual influenza vaccine coverage among controls was 4.5% for the four years. Annual VE estimates adjusted for age, underlying medical conditions and seasonality for 2010-2013 were 54.2% (95% confidence interval (CI): 2.4–78.6%), 57.1% (95% CI: 15.5–78.2%), 38.4% (95% CI: −71.7–78.1%) and 87.2% (95% CI: 67.2–95.0%), respectively. The KAP survey showed that >90% of clinicians were familiar with the indications for and the benefits of influenza vaccination.ConclusionsOur study showed that the vaccine was significantly protective in 2010, 2011 and 2013, but not in 2012 when the circulating A(H3N2) strain showed genetic drift. Vaccine coverage was low despite good clinician knowledge of vaccination indications. Further studies are needed to investigate the reason for the low uptake of influenza vaccine.
Highlights
Influenza vaccine has been available since the mid-1940s and remains the most effective method to prevent influenza disease
Specimens from seven of the nine provinces were tested at the National Institute for Communicable Diseases (NICD), whereas specimens from the other two provinces were tested at central laboratories in those provinces using the same test and assay
9420 patients with Influenza-like illness (ILI) were enrolled over the 4-year study period (Figure 1)
Summary
Influenza vaccine has been available since the mid-1940s and remains the most effective method to prevent influenza disease. Guidelines for the use of influenza vaccine are published annually in South Africa.[2] Since 2009, a limited number of doses have been made available in the public sector for high-risk groups, which include young children, the elderly, pregnant or postpartum (within 2 weeks of delivery) women, and persons of any age with underlying medical conditions (such as heart disease, lung disease and HIV infection). Fewer than 1 million doses have been distributed in the public and private sectors over the past 3 years, despite estimates that more than 20 million South Africans are in groups at high risk of severe influenza disease.[3] The number of doses of influenza vaccine imported into South Africa is based on the uptake of the vaccine during the previous year
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