Estimated global mortality associated with the first 12 months of 2009 pandemic influenza A H1N1 virus circulation: a modelling study

164

139

BackgroundThe global impact of the 2009 influenza A(H1N1) pandemic (H1N1pdm) is not well understood.ObjectivesWe estimate overall and age‐specific prevalence of cross‐reactive antibodies to H1N1pdm virus and rates of H1N1pdm infection during the first year of the pandemic using data from published and unpublished H1N1pdm seroepidemiological studies.MethodsPrimary aggregate H1N1pdm serologic data from each study were stratified in standardized age groups and evaluated based on when sera were collected in relation to national or subnational peak H1N1pdm activity. Seropositivity was assessed using well‐described and standardized hemagglutination inhibition (HI titers ≥32 or ≥40) and microneutralization (MN ≥ 40) laboratory assays. The prevalence of cross‐reactive antibodies to the H1N1pdm virus was estimated for studies using sera collected prior to the start of the pandemic (between 2004 and April 2009); H1N1pdm cumulative incidence was estimated for studies in which collected both pre‐ and post‐pandemic sera; and H1N1pdm seropositivity was calculated from studies with post‐pandemic sera only (collected between December 2009–June 2010).ResultsData from 27 published/unpublished studies from 19 countries/administrative regions – Australia, Canada, China, Finland, France, Germany, Hong Kong SAR, India, Iran, Italy, Japan, Netherlands, New Zealand, Norway, Reunion Island, Singapore, United Kingdom, United States, and Vietnam – were eligible for inclusion. The overall age‐standardized pre‐pandemic prevalence of cross‐reactive antibodies was 5% (95%CI 3–7%) and varied significantly by age with the highest rates among persons ≥65 years old (14% 95%CI 8–24%). Overall age‐standardized H1N1pdm cumulative incidence was 24% (95%CI 20–27%) and varied significantly by age with the highest in children 5–19 (47% 95%CI 39–55%) and 0–4 years old (36% 95%CI 30–43%).ConclusionsOur results offer unique insight into the global impact of the H1N1 pandemic and highlight the need for standardization of seroepidemiological studies and for their inclusion in pre‐pandemic preparedness plans. Our results taken together with recent global pandemic respiratory‐associated mortality estimates suggest that the case fatality ratio of the pandemic virus was approximately 0·02%.

Section: Introductionsupporting

confidence: 66%

Section: Discussionmentioning

confidence: 73%

Estimating age‐specific cumulative incidence for the 2009 influenza pandemic: a meta‐analysis of A(H1N1)pdm09 serological studies from 19 countries

Kerkhove¹,

Hirve

Koukounari

et al. 2013

164

139

“…In addition, HIV‐positive South Africans have been shown to be at greater risk for severe influenza illness 6. The high prevalence of underlying high‐risk medical conditions, including HIV and tuberculosis, likely contributes to higher influenza‐associated mortality in South Africa 7, 8…”

Section: Introductionmentioning

confidence: 99%

Knowledge, attitudes, and practices about influenza illness and vaccination: a cross‐sectional survey in two South African communities

Wong

Cohen

Norris

et al. 2016

BackgroundUnderstanding knowledge and sentiment toward influenza and vaccination is important for effective health messages and prevention strategies. We aimed to characterize knowledge, attitudes, and practices surrounding influenza illness and vaccination in two South African communities and explore reasons for vaccine hesitancy.MethodsHousehold primary caregivers in Soweto and Klerksdorp townships were interviewed about knowledge of influenza and intention to receive an influenza vaccine using a structured questionnaire. Factors associated with unwillingness to receive vaccine were explored using multivariable regression.ResultsWe interviewed representatives of 973 households in Soweto and 1,442 in Klerksdorp. Most respondents in Soweto (692, 71%) and Klerksdorp (1247, 87%) thought weather or cold caused influenza. While most would get a free influenza vaccine, those unwilling to receive vaccine had concerns about efficacy (Soweto: 19%; Klerksdorp: 19%) and safety (Soweto: 17%; Klerksdorp: 10%). In Soweto, females (aRR 2·0, 95% CI 1·3–3·2) and those with higher household income (aRR 1·8, 95% CI 1·2–2·7) were less willing to receive vaccine. In Klerksdorp, more educated respondents (aRR 1·6, 95% CI 1·1–2·4) were less willing to receive vaccine; households reporting an HIV‐positive member were more willing to receive vaccine (aRR 0·3, 95% CI 0·1–0·8).ConclusionsAlthough findings suggest most community participants were amenable to influenza vaccination, knowledge gaps were present. Emphasizing the importance of influenza as a health problem and addressing vaccine safety and efficacy concerns may improve uptake. Populations less amenable to vaccination, including those with higher education and income, may benefit from targeted messaging efforts.

“…Furthermore, few estimates are available about the economic impact‐related caregivers' lost productivity and money spent on over‐the‐counter medications and other out‐of‐pocket expenses. Last, most data are from high‐income countries, despite the fact that influenza occurs in low‐ and middle‐income countries at similar or greater rates 5, 6, 7. To assess the full economic burden of influenza in a middle‐income country, we estimated both the direct and indirect costs among persons enrolled in a community‐based cohort study of influenza in Peru.…”

Section: Introductionmentioning

confidence: 99%

A population‐based estimate of the economic burden of influenza in Peru, 2009–2010

Tinoco

Azziz‐Baumgartner

Rázuri

et al. 2016

IntroductionInfluenza disease burden and economic impact data are needed to assess the potential value of interventions. Such information is limited from resource‐limited settings. We therefore studied the cost of influenza in Peru.MethodsWe used data collected during June 2009–December 2010 from laboratory‐confirmed influenza cases identified through a household cohort in Peru. We determined the self‐reported direct and indirect costs of self‐treatment, outpatient care, emergency ward care, and hospitalizations through standardized questionnaires. We recorded costs accrued 15‐day from illness onset. Direct costs represented medication, consultation, diagnostic fees, and health‐related expenses such as transportation and phone calls. Indirect costs represented lost productivity during days of illness by both cases and caregivers. We estimated the annual economic cost and the impact of a case of influenza on a household.ResultsThere were 1321 confirmed influenza cases, of which 47% sought health care. Participants with confirmed influenza illness paid a median of $13 [interquartile range (IQR) 5–26] for self‐treatment, $19 (IQR 9–34) for ambulatory non‐medical attended illness, $29 (IQR 14–51) for ambulatory medical attended illness, and $171 (IQR 113–258) for hospitalizations. Overall, the projected national cost of an influenza illness was $83–$85 millions. Costs per influenza illness represented 14% of the monthly household income of the lowest income quartile (compared to 3% of the highest quartile).ConclusionInfluenza virus infection causes an important economic burden, particularly among the poorest families and those hospitalized. Prevention strategies such as annual influenza vaccination program targeting SAGE population at risk could reduce the overall economic impact of seasonal influenza.