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. 2022 Sep 7:10:963274.
doi: 10.3389/fped.2022.963274. eCollection 2022.

The burden of hospital-attended influenza in Norwegian children

Håkon Bøås  1 , Terese Bekkevold  1 , Lise Beier Havdal  1   2 , Anne-Marte Bakken Kran  1   3 , Astrid Elisabeth Rojahn  4 , Ketil Størdal  4   5   6 , Sara Debes  7 , Henrik Døllner  8   9 , Svein Arne Nordbø  10   9 , Bjørn Barstad  11 , Elisebet Haarr  12 , Liliana Vázquez Fernández  1 , Britt Nakstad  2   6 , Truls Michael Leegaard  13   14 , Olav Hungnes  1 , Elmira Flem  1 ; Norwegian Enhanced Pediatric Immunisation Surveillance (NorEPIS) Network
Collaborators, Affiliations

The burden of hospital-attended influenza in Norwegian children

Håkon Bøås et al. Front Pediatr. .

Abstract

Background: Norwegian health authorities do not recommend universal pediatric vaccination against seasonal influenza. We aimed to estimate the incidence of influenza by age and underlying medical conditions in hospitalized Norwegian children aged <18 years.

Methods: Active surveillance for influenza in children <18 years was implemented in five hospitals during 2015-18. Children with respiratory symptoms and/or fever were prospectively enrolled and tested for influenza. Surveillance data were linked to health registry data to estimate the national burden of influenza in hospitals.

Results: In 309 (10%) out of 3,010 hospital contacts, the child tested positive for influenza, corresponding to an average incidence of 0.96 hospital-attended influenza cases per 1,000 children <18 years of age. Children <1 year of age (3.8 per 1,000 children) and children with underlying medical conditions (17 per 1,000 children with bronchopulmonary dysplasia) had the highest average incidence. Among <1 year old children, 3% tested positive for influenza, compared to 25% for children aged 6-17. Few children were vaccinated against influenza.

Conclusions: Children <1 year of age and children with underlying medical conditions had a higher incidence of influenza requiring hospital treatment compared to the general population. Effective interventions against seasonal influenza for children in Norway should be considered.

Keywords: children; disease burden; hospital-attended influenza; pediatric; surveillance.

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Conflict of interest statement

Author EF is currently employed by Merck Sharp & Dohme Corp., Drammen, Norway, a subsidiary of Merck & Co., Inc., Kenilworth, NJ. The work for the current study was conducted by EF under the previous affiliation. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

Figures

Figure 1
Figure 1
Flowchart of the recruitment process.
Figure 2
Figure 2
(A) Number of Influenza tested participants, and positivity rate through three influenza seasons. (B) Occurrence of influenza subtypes throughout three surveillance seasons. Black lines are the sum of all influenza cases per week. Blue lines are the sum of all influenza a cases and red line is the sum of all influenza b cases. Not all cases were fully typed due to shortage of material or low viral titers.
Figure 3
Figure 3
(A) Incidence among patients <1 years of age. (B) Incidence among patients 1–5 years of age. (C) Incidence among patients 6–18 years of age. Filled symbols represent national estimates, hollow symbols represent the population living in the catchment area of hospitals participation in NorEpis. formula image: Season 2015/16 formula image: Season 2016–17 formula image: Season 2017/18 formula image: Total of seasons. Filled red and hollow blue symbols indicate inpatients. Filled dark blue and hollow gray symbols indicate outpatients. Filled yellow and hollow purple symbols indicate in- and outpatients combined. *Low number of observations when calculating the probability that a patient is influenza positive given it has one of the ICD-10 codes (95% CI). A one-sided, 97.5% confidence interval was used for calculating the proportions used for the incidence calculation.
See this image and copyright information in PMC

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