An influenza outbreak in a South African mine, following the relaxation of COVID-19 pandemic restrictions, September – December 2021
Introduction: In November 2021, two months after lifting COVID-19 restrictions, a cluster of laboratory-confirmed influenza cases was detected outside of the normal influenza season at a mine in South Africa. We aimed to determine factors associated with influenza infection. Methods: A suspe...
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| Main Authors: | , , , , , , , , , , , , , , , , , , , |
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| Format: | Article |
| Language: | English |
| Published: |
African Field Epidemiology Network
2024-08-01
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| Series: | Journal of Interventional Epidemiology and Public Health |
| Subjects: | |
| Online Access: | https://www.afenet-journal.net/content/article/7/40/full/ |
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| Summary: | Introduction: In November 2021, two months after lifting COVID-19 restrictions, a cluster of laboratory-confirmed influenza cases was detected outside of the normal influenza season at a mine in South Africa. We aimed to determine factors associated with influenza infection.
Methods: A suspected influenza case was an employee presenting with acute onset of ≥1 symptom (fever, cough, rhinorrhoea, sore throat, shortness of breath, loss of smell or taste, myalgia, diarrhoea, nausea, vomiting) or any employee returning from leave or newly recruited. A confirmed influenza case was any person with laboratory-confirmed influenza. We calculated the influenza attack rate among 10 030 mine employees and assessed factors associated with influenza infection from 1 September–13 December 2021 using logistic regression.
Results: There were 3,534 suspected influenza cases of which 161 tested influenza positive (influenza attack rate 1.6%, 161/10 030). Of the suspected influenza cases, 82% (2,886/3,534) were male and the mean age was 40-years. Among the confirmed cases, 87% (140/161) were male and the mean age was 39-years (IQR:31-45). Factors associated with laboratory-confirmed influenza were age 18-35-years (aOR 2.09; 95%CI 1.21-3.60) or 36-49 years (aOR 1.68, 95% CI: 1.02-2.79) vs. ≥50 years and working as an operator (aOR 3.47; 95%CI 1.23-9.75) or in engineering (aOR 3.20; 95%CI 1.03-9.98) vs. in the office. Of the 118 samples that were subtyped, 88 (74.6%) were influenza A(H1N1)pdm09.
Conclusion: Out-of-season influenza outbreaks can occur in semi-closed communities. Influenza vaccines could help reduce illness and work absenteeism. Immediate recommendations included isolation of infected individuals and more personalized education to increase adherence to non-pharmaceutical interventions |
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| ISSN: | 2664-2824 |