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. 2019 Aug 30;69(6):1036-1048.
doi: 10.1093/cid/ciy1017.

Quantifying How Different Clinical Presentations, Levels of Severity, and Healthcare Attendance Shape the Burden of Influenza-associated Illness: A Modeling Study From South Africa

Stefano Tempia  1   2   3 , Sibongile Walaza  3   4 , Jocelyn Moyes  3   4 , Adam L Cohen  1   5 , Meredith L McMorrow  1   2 , Florette K Treurnicht  3   6 , Orienka Hellferscee  3   6 , Nicole Wolter  3   6 , Anne von Gottberg  3   6 , Arthemon Nguweneza  3 , Johanna M McAnerney  3 , Halima Dawood  7   8 , Ebrahim Variava  9   10   11 , Shabir A Madhi  12   13 , Cheryl Cohen  3   4
Affiliations

Quantifying How Different Clinical Presentations, Levels of Severity, and Healthcare Attendance Shape the Burden of Influenza-associated Illness: A Modeling Study From South Africa

Stefano Tempia et al. Clin Infect Dis. .

Abstract

Background: Burden estimates of medically and nonmedically attended influenza-associated illness across syndromes and levels of severity are lacking.

Methods: We estimated the national burden of medically and nonmedically attended influenza-associated illness among individuals with different clinical presentations (all-respiratory, all-circulatory, and nonrespiratory/noncirculatory) and levels of severity (mild, fatal, and severe, nonfatal) using a combination of case-based (from laboratory-confirmed influenza surveillance) and ecological studies, as well as data from healthcare utilization surveys in South Africa during 2013-2015. In addition, we compared estimates of medically attended influenza-associated respiratory illness, obtained from case-based and ecological studies. Rates were reported per 100 000 individuals in the population.

Results: The estimated mean annual number of influenza-associated illness episodes was 10 737 847 (19.8% of 54 096 705 inhabitants). Of these episodes, 10 598 138 (98.7%) were mild, 128 173 (1.2%) were severe, nonfatal, and 11 536 (0.1%) were fatal. There were 2 718 140 (25.6%) mild, 56 226 (43.9%) severe, nonfatal, and 4945 (42.8%) medically attended should be after fatal episodes. Influenza-associated respiratory illness accounted for 99.2% (10 576 146) of any mild, 65.5% (83 941) of any severe, nonfatal, and 33.7% (3893) of any fatal illnesses. Ecological and case-based estimates of medically attended, influenza-associated, respiratory mild (rates: ecological, 1778.8, vs case-based, 1703.3; difference, 4.4%), severe, nonfatal (rates: ecological, 88.6, vs case-based, 75.3; difference, 15.0%), and fatal (rates: ecological, 3.8, vs case-based, 3.5; difference, 8.4%) illnesses were similar.

Conclusions: There was a substantial burden of influenza-associated symptomatic illness, including severe, nonfatal and fatal illnesses, and a large proportion was nonmedically attended. Estimates, including only influenza-associated respiratory illness, substantially underestimated influenza-associated, severe, nonfatal and fatal illnesses. Ecological and case-based estimates were found to be similar for the compared categories.

Keywords: South Africa; burden; influenza; rates.

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Conflict of interest statement

Potential conflicts of interest. A. vG. reports reimbursement for travel expenses from Pfizer and Sanofi. C. C. reports grants from Sanofi Pasteur and Paraxel, outside the submitted work. H. D. reports speaking fees from Merck Sharp and Dohme South Africa, Pfizer South Africa, and Adock Ingram South Africa. S. A. M. reports grants from Bill and Melinda Gates Foundation, Pfizer, GlaxoSmithKline, and Sanofi Pasteur, outside the submitted work. All other authors report no potential conflicts. All authors have submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest. Conflicts that the editors consider relevant to the content of the manuscript have been disclosed.

Figures

Figure 1.
Figure 1.
Schematic of the method used to estimate influenza-associated illness in South Africa, 2013–2015. Each circle represents a compartment (24) in the estimation approach. Abbreviations: All-Cir, all-circulatory; All-Res, all-respiratory; ILI, influenza-like illness; Non-Res/Non-Cir, nonrespiratory/noncirculatory; P&I, pneumonia and influenza; SARI, severe, acute respiratory infection; SRI, severe respiratory illness.
Figure 2.
Figure 2.
Estimated mean annual number of total, medically, and nonmedically attended influenza-associated illness in South Africa, 2013–2015. The () indicate column percentages and [] indicate row percentages. The circles’ size is proportional to the number of influenza-associated illness episodes.
See this image and copyright information in PMC

References

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