[Progress in research of etiology and epidemiology of 2019-nCoV Omicron variant]

Analysis of Symptom Spectra and Associated Factors Among 536 Respondents During the COVID-19 Epidemic in China: A Cross-Sectional Study

Purpose

This study aims to identify common COVID-19 symptoms and asymptomatic infection rates during the epidemic in China. We also introduce the concepts of "Time-point asymptomatic rate" and "Period asymptomatic rate".

Object and Methods

A questionnaire survey was conducted online from December 2022 to January 5, 2023, collecting demographic characteristics, laboratory results, clinical symptoms, lifestyle and vaccination history. Statistical methods were used to analyze symptom characteristics, associated factors, and patterns during an 8-day observation period. Numerical variables were described by median M (Q1-Q3) or mean and standard deviation (). Categorical variables are described by frequency (N), ratio (%) or rate (%). The influencing factors were studied by Wilcoxon or Kruskal-Willis H rank sum test or logistic regression analysis, and the trend of symptom incidence by Spearman rank correlation. P value being ≤0.05 was statistically significant.

Results

Out of 536 participants, 493 (91.98%) were infected, with 3 asymptomatic cases and 490 symptomatic cases within 8 days. The time-point asymptomatic rate increased from 0.61% on day 1 to 15.42% on day 8. Fever, cough, and fatigue were the main symptoms, with additional symptoms such as vomiting, diarrhea, and hyposmia reported. Symptom durations varied, with cough and expectoration lasting longer and vomiting and diarrhea lasting shorter. Several symptoms showed a downward trend over time.

Conclusion

Our online survey highlighted that most COVID-19 patients experienced symptoms, and the time-point asymptomatic rate showed a dynamic change among the infected population. Onset patterns and demographic factors influence symptom occurrence and duration. These findings have implications for clinical practitioners and decision-makers in public health measures and strategies.

Study on the COVID-19 epidemic in mainland China between November 2022 and January 2023, with prediction of its tendency

The prediction system EpiSIX was used to study the COVID-19 epidemic in mainland China between November 2022 and January 2023, based on reported data from December 9, 2022, to January 30, 2023, released by The Chinese Center for Disease Control and Prevention on February 1, 2023. Three kinds of reported data were used for model fitting: the daily numbers of positive nucleic acid tests and deaths, and the daily number of hospital beds taken by COVID-19 patients. It was estimated that the overall infection rate was 87.54% and the overall case fatality rate was 0.078%–0.116% (median 0.100%). Assuming that a new COVID-19 epidemic outbreak would start in March or April of 2023, induced by a slightly more infectious mutant strain, we predicted a possible large rebound between September and October 2023, with a peak demand of between 800,000 and 900,000 inpatient beds. If no such new outbreak was induced by other variants, then the current COVID-19 epidemic course in mainland China would remain under control until the end of 2023. However, it is suggested that the necessary medical resources be prepared to manage possible COVID-19 epidemic emergencies in the near future, especially for the period between September and October 2023.