The omicron variant of coronavirus disease 2019 (COVID-19) has caused a global epidemic in 2022. The aim was to investigate the symptom spectrum and risk factors for fever in pediatric and adult patients with omicron infection. From April 8, 2022 to May 17, 2022, this prospective observational study included patients who attended the child-parent sections of the Fangcang shelter hospitals with laboratory-confirmed COVID-19. Patient data were collected from questionnaires. The risk factors for prolonged fever and high fever were identified by univariate and multivariate analyses.

Study design and participants A prospective multicenter study was designed. It was conducted in accordance with the Declaration of Helsinki (as revised in 2013). Informed consent was obtained for all participants. From April 8, 2022 to May 17, 2022, Patients who attended the child-parent sections of the Fangcang shelter hospitals in Shanghai, China, with laboratory-confirmed COVID-19 were included. Those who had poor compliance (defined as inability to comply with the protocol) were excluded. Data from the included cases were collected. Adult patients and caregivers of children patients received two kinds of questionnaires after admission. Type I questionnaire (supplemental material) for basic characteristic were finished as soon as they were admitted. Type II questionnaire (supplemental material) for symptom and medication use tracking were filled out every day until discharge. This study was approved by the ethics committee of Shanghai Children's Medical Center.

Definition of outcomes The outcomes were the likelihood of developing prolonged fever and the likelihood of developing high fever. Fever was defined as temperature ≥ 38.0℃. Prolonged fever was defined as fever for more than 2 days. High fever was defined as temperature ≥ 39.1℃.

Statistical analysis SPSS version 25.0 (IBM SPSS Statistics, Armonk, NY, USA) was used to analyze the data. Data are presented as median values and interquartile ranges (IQRs) for continuous variables and frequencies and percentages for categorical variables. The investigators used Mann-Whitney U test to compare continuous variables between two groups. The investigators used χ2 test or Fisher exact test to compare categorical variables. Univariable analysis was used to investigate the association of each clinical variable with the outcomes. To determine the risk factors for each outcome, multivariable analysis was performed by logistic regression with a stepwise variable model. Variables of P value < 0.05 were candidates for multivariable analysis. Statistical significance was determined as a 2-sided P value of < 0.05.

Inclusion Criteria:

• hospitalized in the child-parent sections of the Fangcang shelter hospitals in Shanghai, China
• diagnosis of laboratory-confirmed COVID-19

Exclusion Criteria:

● have poor compliance (defined as inability to comply with the protocol)

Patients who attended the child-parent sections of the Fangcang shelter hospitals in Shanghai, China, with laboratory-confirmed COVID-19