Introduction:
Influenza may be correlated with a high number of complications and generate high costs of treatment. The study aimed to estimate the socioeconomic significance of hospitalized influenza cases.

Material and methods:
In the 2015–2016 flu season 157 children (median age 17 months) were hospitalized in the Department of Pediatrics. The diagnosis was confirmed with the rapid influenza diagnostic test (RIDT), polymerase chain reaction (PCR) or both. The study assessed the direct and indirect costs of hospitalization, including the cost of treatment, work absence and the related income lost.

Results:
The frequency of complications among the children hospitalized was 57.3% (90/157), mainly due to pneumonia (31%) and bronchitis (23%). Patients with complications required longer hospital treatment (8 vs. 6 days, p < 0.01) and generated a higher total cost (€ 1042 vs. € 779, p < 0.01), including the patient’s and systemic costs (€123 vs. € 94, p < 0.01 and € 916 vs. € 690, p < 0.01, respectively). Patients with complications had a 3.5-fold higher risk of generating higher (i.e., above median) costs. The difference in the costs between children aged under 2 and those over 2 years old was greater than the difference between children aged under 5 and those over 5 years old (€ 358 vs. € 253).

Conclusions:
Influenza complications generate higher systemic and patient’s costs, both direct and indirect. The group of children for whom the difference is especially marked is under 2 years of age.