Characteristics of children with influenza admitted to a pediatric hospital in Greece during the 2022/2023 and 2023/2024 seasons.

Influenza results in high morbidity and mortality globally each year. Data on pediatric influenza in Greece after the COVID-19 pandemic are lacking. This study aims to evaluate the characteristics of outpatient and hospitalized pediatric influenza cases post COVID-19 pandemic in Greece. A retrospective observational study was conducted. Children 0-16 years old with laboratory-confirmed influenza presented to the emergency department of a children's hospital during the 2022-2023 and 2023-2024 influenza seasons were studied. A total of 976 children (mean age 7 years, males 53.9%) were enrolled, and 4.8% had a history of influenza vaccination. Compared to unvaccinated children, vaccinated patients had more comorbidities (29.8% vs. 3.3%, p < 0.001) and high-risk contacts (4.3% vs. 0.7%, p = 0.014). A total of 223 children (22.8%) were hospitalized, significantly younger than outpatients (mean age 5.7 vs. 7.4 years, p < 0.001). Younger age, presence of comorbidities, and symptoms such as vomiting, myositis, and respiratory distress were significantly associated with hospitalization (p < 0.001). Vaccination did not reduce the risk of hospitalization (OR 0.70, 95%CI 0.30-1.63, p = 0.405). Hospitalized children more frequently experienced complications (48.0% vs. 16.7%) and received antibiotics (34.2% vs. 14.4%) and oseltamivir (78.9% vs. 41.9%) (p < 0.001). Main complications among hospitalized patients included myositis (12.5%), acute otitis media (12.1%), febrile seizures (8.9%), and pneumonia (8.5%). Two unvaccinated children with comorbidities were admitted to the PICU; one died due to acute necrotizing encephalopathy.

conclusionHospitalized children with influenza presented with serious complications. Although only 13% of them had comorbidities, nearly half experienced complications during hospitalization. The recently introduced universal immunization of children < 5 years old in Greece is expected to reduce influenza morbidity in this population. WHAT IS KNOWN: •Influenza is an acute respiratory viral infection that has a significant impact on public health, representing a major cause of morbidity and mortality worldwide. •To date, there are no published data on children with influenza in Greece in the post-COVID-19 era. WHAT IS NEW: •This study highlights the burden of influenza-associated ED visits and hospitalizations in Greece, particularly among younger children and those with comorbidities. •While influenza vaccination did not decrease the risk of hospitalization in this cohort, this most likely is attributed to the low vaccination rate and higher prevalence of comorbidities in the vaccinated group.