Global burden of respiratory infections due to seasonal influenza in young children: a systematic review and meta-analysis

BackgroundInfluenza is an important cause of respiratory illness in children, but data are limited on hospitalized children with laboratory‐confirmed influenza in China.MethodsWe conducted active surveillance for severe acute respiratory infection (SARI; fever and at least one sign or symptom of acute respiratory illness) among hospitalized pediatric patients in Jingzhou, Hubei Province, from April 2010 to April 2012. Data were collected from enrolled SARI patients on demographics, underlying health conditions, clinical course of illness, and outcomes. Nasal swabs were collected and tested for influenza viruses by reverse transcription polymerase chain reaction. We described the clinical and epidemiological characteristics of children with influenza and analyzed the association between potential risk factors and SARI patients with influenza.ResultsDuring the study period, 15 354 children aged <15 years with signs and symptoms of SARI were enrolled at hospital admission. severe acute respiratory infection patients aged 5–15 years with confirmed influenza (H3N2) infection were more likely than children without influenza to have radiographic diagnosis of pneumonia (11/31, 36% vs 15/105, 14%. P<.05). Only 16% (1116/7145) of enrolled patients had received seasonal trivalent influenza vaccination within 12 months of hospital admission. Non‐vaccinated influenza cases were more likely than vaccinated influenza cases to have pneumonia (31/133, 23% vs 37/256, 15%, P<.05). severe acute respiratory infection cases aged 5–15 years diagnosed with influenza were also more likely to have a household member who smoked cigarettes compared with SARI cases without a smoking household member (54/208, 26% vs 158/960, 16%, P<.05).ConclusionsInfluenza A (H3N2) virus infection was an important contributor to pneumonia requiring hospitalization. Our results highlight the importance of surveillance in identifying factors for influenza hospitalization, monitoring adherence to influenza prevention and treatment strategies, and evaluating the disease burden among hospitalized pediatric SARI patients. Influenza vaccination promotion should target children.

Section: Discussionsupporting

confidence: 93%

Clinical characteristics and factors associated with severe acute respiratory infection and influenza among children in Jingzhou, China

Yang¹,

Guan

Liu

et al. 2016

“…Influenza‐associated hospitalizations rates in this study were similar to those published in a recent global meta‐analysis1 which reported a rate of 1 (95% CI: 1–2) per 1000 person‐years among children aged <5 years. Costa Rica used similar methods6 and obtained comparable results.…”

Section: Discussionsupporting

confidence: 88%

“…Our rates among children aged <5 years were also lower than those of a global meta‐analysis using different methodology,1 whereby 4·9 children per 100 000 died from influenza‐associated severe acute lower respiratory infection (ALRI) in developing countries. A plausible reason for these discrepancies could be the incompleteness and underreporting in mortality registries in study countries 14.…”

Section: Discussioncontrasting

confidence: 55%

Estimating the burden of influenza‐associated hospitalizations and deaths in Central America

Descalzo

Clara²,

Guzman

et al. 2016

ObjectivesOur objective was to estimate the incidence of influenza‐associated hospitalizations and in‐hospital deaths in Central American Region.Design and settingWe used hospital discharge records, influenza surveillance virology data, and population projections collected from Costa Rica, El Salvador, Guatemala, Honduras, and Nicaragua to estimate influenza‐associated hospitalizations and in‐hospital deaths. We performed a meta‐analysis of influenza‐associated hospitalizations and in‐hospital deaths.Main outcome measuresThe highest annual incidence was observed among children aged <5 years (136 influenza‐associated hospitalizations per 100 000 persons).ResultsAnnually, 7 625–11 289 influenza‐associated hospitalizations and 352–594 deaths occurred in the subregion.ConclusionsOur results suggest that a substantive number of persons are annually hospitalized because of influenza. Health officials should estimate how many illnesses could be averted through increased influenza vaccination.

“…Influenza may affect up to 10% of the world's population every year 1 with substantial morbidity and mortality 2, 3, 4, 5. With immunization being one of the most powerful and cost effective interventions against infectious diseases,6 vaccination remains the main strategy to protect populations against influenza‐associated morbidity and mortality.…”

Section: Introductionmentioning

confidence: 99%

Seasonal influenza vaccine policy, use and effectiveness in the tropics and subtropics – a systematic literature review

Hirve

Lambach

Paget

et al. 2016

AimThe evidence needed for tropical countries to take informed decisions on influenza vaccination is scarce. This article reviews policy, availability, use and effectiveness of seasonal influenza vaccine in tropical and subtropical countries.MethodGlobal health databases were searched in three thematic areas – policy, availability and protective benefits in the context of human seasonal influenza vaccine in the tropics and subtropics. We excluded studies on monovalent pandemic influenza vaccine, vaccine safety, immunogenicity and uptake, and disease burden.ResultsSeventy‐four countries in the tropics and subtropics representing 60% of the world's population did not have a national vaccination policy against seasonal influenza. Thirty‐eight countries used the Northern Hemisphere and 21 countries the Southern Hemisphere formulation. Forty‐six countries targeted children and 57 targeted the elderly; though, the age cut‐offs varied. Influenza vaccine supply increased twofold in recent years. However, coverage remained lower than five per 1000 population. Vaccine protection against laboratory‐confirmed influenza in the tropics ranged from 0% to 42% in the elderly, 20–77% in children and 50–59% in healthy adults. Vaccinating pregnant women against seasonal influenza prevented laboratory‐confirmed influenza in both mothers (50%) and their infants <6 months (49–63%).ConclusionGuidelines on vaccine composition, priority risk groups and vaccine availability varied widely. The evidence on vaccine protection was scarce. Countries in the tropics and subtropics need to strengthen and expand their evidence‐base required for making informed decisions on influenza vaccine introduction and expansion, and how much benefit to expect.