AUTHOR=Abudunaibi Buasiyamu , Liu Weikang , Guo Zhinan , Zhao Zeyu , Rui Jia , Song Wentao , Wang Yao , Chen Qiuping , Frutos Roger , Su Chenghao , Chen Tianmu 

TITLE=A comparative study on the three calculation methods for reproduction numbers of COVID-19

JOURNAL=Frontiers in Medicine

VOLUME=9

YEAR=2023

URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2022.1079842

DOI=10.3389/fmed.2022.1079842

ISSN=2296-858X

ABSTRACT=<sec><title>Objective</title><p>This study uses four COVID-19 outbreaks as examples to calculate and compare merits and demerits, as well as applicational scenarios, of three methods for calculating reproduction numbers.</p></sec><sec><title>Method</title><p>The epidemiological characteristics of the COVID-19 outbreaks are described. Through the definition method, the next-generation matrix-based method, and the epidemic curve and serial interval (<italic>SI</italic>)-based method, corresponding reproduction numbers were obtained and compared.</p></sec><sec><title>Results</title><p>Reproduction numbers (<italic>R</italic><sub><italic>eff</italic></sub>), obtained by the definition method of the four regions, are 1.20, 1.14, 1.66, and 1.12. Through the next generation matrix method, in region H <italic>R</italic><sub><italic>eff</italic></sub> = 4.30, 0.44; region P <italic>R</italic><sub><italic>eff</italic></sub> = 6.5, 1.39, 0; region X <italic>R</italic><sub><italic>eff</italic></sub> = 6.82, 1.39, 0; and region Z <italic>R</italic><sub><italic>eff</italic></sub> = 2.99, 0.65. Time-varying reproduction numbers (<italic>R</italic><sub><italic>t</italic></sub>), which are attained by <italic>SI</italic> of onset dates, are decreasing with time. Region H reached its highest <italic>R</italic><sub><italic>t</italic></sub> = 2.8 on July 29 and decreased to <italic>R</italic><sub><italic>t</italic></sub> &lt; 1 after August 4; region P reached its highest <italic>R</italic><sub><italic>t</italic></sub> = 5.8 on September 9 and dropped to <italic>R</italic><sub><italic>t</italic></sub> &lt; 1 by September 14; region X had a fluctuation in the <italic>R</italic><sub><italic>t</italic></sub> and <italic>R</italic><sub><italic>t</italic></sub> &lt; 1 after September 22; <italic>R</italic><sub><italic>t</italic></sub> in region Z reached a maximum of 1.8 on September 15 and decreased continuously to <italic>R</italic><sub><italic>t</italic></sub> &lt; 1 on September 19.</p></sec><sec><title>Conclusion</title><p>The reproduction number obtained by the definition method is optimal in the early stage of epidemics with a small number of cases that have clear transmission chains to predict the trend of epidemics accurately. The effective reproduction number <italic>R</italic><sub><italic>eff</italic></sub>, calculated by the next generation matrix, could assess the scale of the epidemic and be used to evaluate the effectiveness of prevention and control measures used in epidemics with a large number of cases. Time-varying reproduction number <italic>R</italic><sub><italic>t</italic></sub>, obtained <italic>via</italic> epidemic curve and <italic>SI</italic>, can give a clear picture of the change in transmissibility over time, but the conditions of use are more rigorous, requiring a greater sample size and clear transmission chains to perform the calculation. The rational use of the three methods for reproduction numbers plays a role in the further study of the transmissibility of COVID-19.</p></sec>