Clinical and socioeconomic impact of moderate-to-severe versus mild influenza in children

Abstract

Some studies have assessed the efficacy of influenza vaccination in children separately for moderate-to-severe and any influenza, but the definition used for identifying children with moderate-to-severe illness has not been validated. We analyzed clinical and socioeconomic data from two prospective cohort studies of respiratory infections among children aged ≤13 years (four influenza seasons, 3,416 child-seasons of follow-up). We categorized children with laboratory-confirmed influenza into two mutually exclusive groups of moderate-to-severe and mild influenza using the previously proposed criteria. We obtained the data for the analyses from structured medical records filled out by the study physicians and from daily symptom cards filled out by the parents. Of 434 cases of influenza, 217 (50 %) were classified as moderate-to-severe and 217 (50 %) as mild. The mean duration of fever was 4.0 days in children with moderate-to-severe influenza and 3.1 days in those with milder illness (P < 0.0001). Antibiotics were prescribed to 111 (51 %) children with moderate-to-severe and to ten (5 %) children with mild influenza (P < 0.0001). The rates of parental work absenteeism were 184 days per 100 children with moderate-to-severe influenza and 135 days per 100 children with mild influenza (P = 0.02). The corresponding rates of children's own absenteeism from day care or school were 297 and 233 days respectively per 100 children (P = 0.006). Categorization of children into groups with moderate-to-severe and mild influenza is meaningful, and it identifies children in whom the clinical and socioeconomic impact of influenza is highest. Illness severity should be considered when assessing influenza vaccine effectiveness in children.

Vaccination against Paediatric Respiratory Pathogens

“…Together with the elderly population, children under 5 years of age, even in the absence of underlying chronic diseases, have the highest risk of severe disease leading to hospitalization and, although rarely, to death [25]. Influenza is estimated to be the cause of approximately 374,000 hospitalizations of children <1 year of age and 870,000 hospitalizations of children <5 years of age annually [26][27][28][29][30][31][32]. Moreover, children are the most important cause of the spread of the infection in communities because they shed the virus in greater amounts and for longer periods of time than adults [33].…”

Retrospective study of the use of an influenza disease two-tiered classification system to characterize clinical severity in US children

“…Our results are generally consistent with a prior study in Finland, with their study finding that 65.8% of children aged <36 months, and 41.5% of children aged 3 to 13 years had M-S influenza. 7 However, the Finnish study noted that fever (40%) and AOM (26%) were the most frequently observed symptoms in all ages, while LRTI was only diagnosed in 8% of their cohort. 7 The Finnish study prospectively recruited children with respiratory infections in the outpatient setting.…”

“…While antibiotic use as an outcome may be related to components of the M-S influenza disease definition (i.e., diagnosis of AOM and/or LRTI), we included this outcome for comparative purposes because it was also assessed in prior evaluations of this M-S definition. 7,8…”

“…In this study, we used a novel influenza severity definition that has been utilized in other (non-US) clinical and observational studies [5][6][7][8] to characterize whether US children classified retrospectively as having moderate-to-severe influenza disease had an increased likelihood of utilizing healthcare, including having antibiotics or antivirals prescribed. Overall, this study found that children identified as having moderate-to-severe disease had an increased likelihood of being prescribed antibiotics, having ED visits, and subsequent outpatient visits when compared with children with mild disease.…”

Protection of children against influenza: Emerging problems

“…2 Lafond et al estimated that worldwide, influenza is the cause of approximately 374,000 hospitalizations in children <1 year of age (of which 228,000 occur in children <6 months of age) and 870,000 hospitalizations in children <5 years of age annually. 3,4 In the last four influenza seasons in the USA, a total of 515 influenza-associated pediatric deaths have occurred. 5 However, it is highly likely that the true impact of influenza infection in pediatrics is significantly higher than what is reported in epidemiological studies and official statistics.…”