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Review
. 2024 Jan 18;24(1):100.
doi: 10.1186/s12879-023-08685-z.

Uncovering the burden of Influenza in children in Portugal, 2008-2018

Alberto Caldas Afonso  1   2   3   4 , Catarina Gouveia  5   6 , Gustavo Januário  7   8 , Mafalda Carmo  9 , Hugo Lopes  10   11   12 , Hélène Bricout  13 , Catarina Gomes  14 , Filipe Froes  15
Affiliations
Review

Uncovering the burden of Influenza in children in Portugal, 2008-2018

Alberto Caldas Afonso et al. BMC Infect Dis. .

Abstract

Background: Despite their higher risk of developing severe disease, little is known about the burden of influenza in Portugal in children aged < 5 years old. This study aims to cover this gap by estimating the clinical and economic burden of severe influenza in children, in Portugal, during ten consecutive influenza seasons (2008/09-2017/18).

Methods: We reviewed hospitalizations in children aged < 5 years old using anonymized administrative data covering all public hospitals discharges in mainland Portugal. The burden of hospitalization and in-hospital mortality directly coded as due to influenza was supplemented by the indirect burden calculated from excess hospitalization and mortality (influenza-associated), estimated for four groups of diagnoses (pneumonia or influenza, respiratory, respiratory or cardiovascular, and all-cause), through cyclic regression models integrating the incidence of influenza. Means were reported excluding the H1N1pdm09 pandemic (2009/10).

Results: The mean annual number of hospitalizations coded as due to influenza was 189 (41.3 cases per 100,000 children aged < 5 years old). Hospitalization rates decreased with increasing age. Nine-in-ten children were previously healthy, but the presence of comorbidities increased with age. Children stayed, on average, 6.1 days at the hospital. Invasive mechanical ventilation was used in 2.4% of hospitalizations and non-invasive in 3.1%. Influenza-associated excess hospitalizations between 2008 and 2018 were estimated at 1,850 in pneumonia or influenza, 1,760 in respiratory, 1,787 in respiratory or cardiovascular, and 1,879 in all-cause models. A total of 95 influenza-associated excess deaths were estimated in all-cause, 14 in respiratory or cardiovascular, and 9 in respiratory models. Over ten years, influenza hospitalizations were estimated to have cost the National Health Service at least €2.9 million, of which 66.5% from healthy children.

Conclusions: Influenza viruses led to a high number of hospitalizations in children. Most were previously healthy. Results should lead to a reflection on the adequate preventive measures to protect this age group.

Keywords: Burden; Children; Excess; Healthy; Hospitalization; Influenza; Mortality; Portugal.

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Conflict of interest statement

CG and HB are Sanofi employees. MC and HL are IQVIA employees. GJ reports personal fees from Sanofi outside the submitted work. FF reports Advisory Board and personal fees from Sanofi, Pfizer, MSD, Gilead and personal fees or non-financial support from Bial, AstraZeneca, GSK, Novartis, Boehringer Ingelheim, Tecnifar, Lilly, Bayer and Roche outside the submitted work. ACA and CG have no conflicts of interest to declare.

Figures

Fig. 1
Fig. 1
Weekly hospitalizations in children aged < 5 years old, by groups of ICD-9/10 codes, in Portuguese public hospitals, between 1st January 2008–31st December 2018
Fig. 2
Fig. 2
Percentage of hospitalizations diagnosed as due to influenza in children aged < 5 years old by length-of-stay at the hospital, in Portuguese public hospitals, between 2008/09 and 2017/18
Fig. 3
Fig. 3
Direct cost of hospitalizations coded as due to influenza in children aged < 5 years old by months of age and epidemic season, in Portuguese public hospitals, between 2008/09 and 2017/18 (million €)
See this image and copyright information in PMC

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