Clinical characteristics of pediatric influenza hospitalization

A study recently published in Frontiers aimed to identify clinical characteristics and risk factors associated with pediatric influenza after mandatory COVID-19 restrictions were lifted in China.

Over the last 2 winters, influenza incidence was low and influenza-associated hospitalization fell to the lowest level in decades, according to study authors. China’s national policy to prevent COVID-19 shifted on December 7, 2022, and the positive rate of SARS-CoV-2 continued to rise.

Influenza remained consistently low until February 2023, though it began to rise before peaking in March. The study investigators stated that the uptick in influenza cases was predicted as a result of the loosened COVID-19 restrictions, paired with the loss of natural immunity in seasons prior to 2023.

The authors sought to determine risk factors of hospitalization by investigating, “the clinical manifestation of hospitalized pediatric patients with seasonal influenza circulating in the early year 2023, revealing the key determinants for pneumonia development.”

The retrospective study featured 1006 pediatric patients who were infected with influenza A (IAV) and admitted to The Affiliated Hospital of Jiangsu University (TAHJU) in Zhenjiang City from February to April 2023.

Patients with certain underlying diseases that could seriously impact blood profiles, including hematological disorders, malignancy, or autoimmune deficiency, were excluded.

Patients were divided into outpatient (n = 798) and inpatient (n = 208) groups. Baseline characteristics were compared to conclude the risk factors for hospitalization. The pediatric inpatients were further divided into pneumonia and non-pneumonia groups with comparison to clinical characteristics (laboratory test results, representative radiological features) to derive key determinants for pneumonia development after hospitalization.

Median age for all patients was 6.0 years (IQR 4.0-9.0), and 45.9% were female. Overall, 29.9% of patients were infected with influenza B (IBV), and no patients experienced asymptomatic influenza.

Inpatients were significantly younger, had a higher female proportion, and more IBV co-infection compared to outpatients.

Of the 208 pediatric inpatients (median age 5.0 years [IQR 4.0-7.0 years]), 23.6% developed pneumonia with a median hospitalization of 5.0 days (IQR 4.0-6.0 days), where the pneumonia group had a significantly longer hospital stay compared to the non-pneumonia group.

The pneumonia group had a significantly higher incidence of mycoplasma infection compared to the non-pneumonia group, and the increased number of co-infections was not linked to increased occurrence in patients that acquired pneumonia.

In the multivariate regression analysis, independent risk factors of hospitalization were determined to be clinical symptom of pain (OR = 2.63, [95% CI, 1.05–6.57], P = 0.039), elevated levels of lymphocytes (OR = 2.24, [95% CI,1.65–3.05], P = 0.001), co-infection of IBV (OR = 44.33, [95% CI, 25.10–78.30], P = 0.001), and c-reactive proteins upon hospital admission (OR = 1.06, [95% CI, 1.03–1.08], P = 0.001).

Cough symptom (OR = 17.39, [95% CI, 3.51–86.13], P = 0.001) and hospitalization length (OR = 1.36, [95% CI, 1.12–1.67], P = 0.002) were deemed to be risk factors of pneumonia acquirement for inpatients.

Overall, the study authors concluded that abdominal pain, viral co-infection and hematological abnormality are main factors contributing to hospitalization in pediatric patients with IAV infection.

In addition, the authors noted, “the length of hospital stay and clinical sign of coughing upon hospital admission constitute the key determinants for nosocomial pneumonia development.”

Reference:

Zhang Y, Huang X, Zhang J, Tao Z. Risk factors for hospitalization and pneumonia development of pediatric patients with seasonal influenza during February–April 2023. Front Public Health. 2024;11:1300228. doi:10.3389/fpubh.2023.1300228