Introduction of 2009 Pandemic Influenza A Virus Subtype H1N1 Into South Africa: Clinical Presentation, Epidemiology, and Transmissibility of the First 100 Cases

Archer, Brett N.; Timothy, Geraldine Antoinette; Cohen, Cheryl; Tempia, Stefano; Huma, M.; Blumberg, Lucille; Naidoo, Dhamari; Cengimbo, Ayanda; Schoub, Barry D.

doi:10.1093/infdis/jis583

Cited by 18 publications

(20 citation statements)

References 13 publications

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“…SIR for laboratory-confirmed influenza and ARI were higher than what has been reported in previous studies and studies from other countries, 2–4 but are consistent with the study done in South Africa on pandemic influenza. 14 There is a large burden of respiratory symptoms in this community, yet household contacts did not report changing behaviors to prevent transmission, influenza vaccination rates were low, and risk factors of crowded sleeping conditions and spending time in the home with the index case were reported. Education on transmission-reducing behaviors could guide public health measures to improve influenza transmission control in households in similar settings.…”

Section: Discussionmentioning

confidence: 87%

“…1,3,6–8 Our findings are consistent with the range of results reported by a study done on pandemic influenza in South Africa. 14 In that study, the authors were unable to perform confirmatory testing on all cases, but estimated a SIR of pandemic influenza ranging from 10% (laboratory-confirmed cases) to 17% (including symptomatic cases who did not have confirmatory testing), and a serial interval of transmission of 2.3 days. 14 …”

Section: Discussionmentioning

confidence: 99%

“…2,9–13 To date there have been few reports on household transmission of seasonal influenza in middle-income countries such as South Africa. 14–18 South Africa has a temperate climate and influenza is highly seasonal circulating in the Southern hemisphere winter between May and September each year. 19 The estimated annual incidence of influenza-associated hospitalization for lower respiratory tract infection was approximately 50 per 100,000 population during non-pandemic years (2010–2011), and data from national surveillance indicate that 9% of patients hospitalized for acute lower respiratory tract infections had respiratory specimens that tested positive for influenza.…”

Section: Introductionmentioning

confidence: 99%

“…20 However, there are few data describing the household transmission of influenza virus in South Africa. 14 …”

Section: Introductionmentioning

confidence: 99%

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Case-ascertained study of household transmission of seasonal influenza — South Africa, 2013

Iyengar

Mollendorf

Tempia³

et al. 2015

Journal of Infection

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Summary Objectives The household is important in influenza transmission due to intensity of contact. Previous studies reported secondary attack rates (SAR) of 4–10% for laboratory-confirmed influenza in the household. Few have been conducted in middle-income countries. Methods We performed a case-ascertained household transmission study during May–October 2013. Index cases were patients with influenza-like-illness (cough and self-reported or measured fever (≥38 °C)) with onset in the last 3 days and no sick household contacts, at clinics in South Africa. Household contacts of index cases with laboratory-confirmed influenza were followed for 12 days. Results Thirty index cases in 30 households and 107/110 (97%) eligible household contacts were enrolled. Assuming those not enrolled were influenza negative, 21/110 household contacts had laboratory-confirmed influenza (SAR 19%); the mean serial interval was 2.1 days (SD = 0.35, range 2–3 days). Most (62/82; 76%) household contacts who completed the risk factor questionnaire never avoided contact and 43/82 (52%) continued to share a bed with the index case after illness onset. Conclusion SAR for laboratory-confirmed influenza in South Africa was higher than previously reported SARs. Household contacts did not report changing behaviors to prevent transmission. These results can be used to understand and predict influenza transmission in similar middle-income settings.

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Section: Discussionmentioning

confidence: 87%

Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…20 However, there are few data describing the household transmission of influenza virus in South Africa. 14 …”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Case-ascertained study of household transmission of seasonal influenza — South Africa, 2013

Iyengar

Mollendorf

Tempia³

et al. 2015

Journal of Infection

View full text Add to dashboard Cite

show abstract

“…The mean and 95% CI for the mean of the serial interval are 2.17 (1.78-2.62) days in South Africa, which are comparable to other reported estimated from this outbreak. 28,29,34 In Japan, a slightly higher mean SI estimate was obtained, 2.78 (2.26-3.33) days.…”

Section: Resultsmentioning

confidence: 91%

Estimating age-specific reproductive numbers—A comparison of methods

Moser

White

2016

Stat Methods Med Res

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Large outbreaks, such as those caused by influenza, put a strain on resources necessary for their control. In particular, children have been shown to play a key role in influenza transmission during recent outbreaks, and targeted interventions, such as school closures, could positively impact the course of emerging epidemics. As an outbreak is unfolding, it is important to be able to estimate reproductive numbers that incorporate this heterogeneity and to use surveillance data that is routinely collected to more effectively target interventions and obtain an accurate understanding of transmission dynamics. There are a growing number of methods that estimate age-group specific reproductive numbers with limited data that build on methods assuming a homogenously mixing population. In this article, we introduce a new approach that is flexible and improves on many aspects of existing methods. We apply this method to influenza data from two outbreaks, the 2009 H1N1 outbreaks in South Africa and Japan, to estimate age-group specific reproductive numbers and compare it to three other methods that also use existing data from social mixing surveys to quantify contact rates among different age groups. In this exercise, all estimates of the reproductive numbers for children exceeded the critical threshold of one and in most cases exceeded those of adults. We introduce a flexible new method to estimate reproductive numbers that describe heterogeneity in the population.

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A method to estimate the serial interval distribution under partially-sampled data

Susvitasari,

Tupper,

Stockdale

et al. 2023

Epidemics

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Introduction of 2009 Pandemic Influenza A Virus Subtype H1N1 Into South Africa: Clinical Presentation, Epidemiology, and Transmissibility of the First 100 Cases

Abstract: A(H1N1)pdm09 established itself rapidly in South Africa. Transmissibility of the virus was comparable to observations from outside of Africa and to seasonal influenza virus strains.

Cited by 18 publications

References 13 publications

Case-ascertained study of household transmission of seasonal influenza — South Africa, 2013

Case-ascertained study of household transmission of seasonal influenza — South Africa, 2013

Estimating age-specific reproductive numbers—A comparison of methods

A method to estimate the serial interval distribution under partially-sampled data

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