2.2 Data collection and specimen detection
The study participants’ clinical characteristics, including age, sex, length of stay, season of hospitalization, pathogen, allergen-specific IgE (sIgE) and micronutrient levels were collected from the electronic medical records.
Peripheral blood samples and respiratory specimens were obtained on admission by trained nurses following standard operating procedures. Pathogen detections were conducted, including: bacterial cultures prepared from secretions of lower respiratory tracts; direct immunofluorescence assay for the virus antibody tests, including respiratory syncytial virus (RSV), adenovirus (ADV), influenza virus (IV), parainfluenza virus (PIV) and coxsackie virus; and mycoplasma pneumonia (Mp) IgM tested with ELISA. Mp infection was defined as seropositivity of Mp IgM in the acute stage.
Five main allergens, namely house dust mite, milk, egg white, shrimp and crab were evaluated in this study. Serum sIgE was measured by ImmunoCAP, and concentration ≥ 0.35 IU/ml was considered as positive, otherwise, as negative19.
The explored micronutrients in our study included vitamin A, B1, B2, B6, C, serum 25-hydroxyvitamin D (25(OH)D), calcium (Ca) and zinc (Zn). Vitamins were analyzed with electrochemical detection, while calcium and zink were determined with atomic absorption spectrometry.