Elsevier established a free COVID-19 resource center in January 2020, offering information in English and Mandarin. The center is hosted on Elsevier Connect, and Elsevier grants permission to freely share its COVID-19 research in PubMed Central and other repositories. A letter to the editor estimates the asymptomatic ratio of COVID-19 infections using data from Japanese nationals evacuated from Wuhan. By February 6, 2020, 565 citizens were evacuated, with 63 (11.2%) showing symptoms upon arrival. RT-PCR testing revealed 4 asymptomatic and 9 symptomatic positive cases. Using Bayes' theorem, the asymptomatic ratio was calculated as 30.8% (95% CI 7.7–53.8%). The study suggests that less than half of infected individuals may be asymptomatic, slightly lower than the 56–80% estimated for influenza. The study acknowledges limitations, including age-related heterogeneity and a small sample size. Further research is needed to better understand asymptomatic infections and guide epidemic control. The authors declare no conflict of interest and received funding from various Japanese institutions. The study uses data from evacuated passengers, providing insights into asymptomatic viral shedding. The findings highlight the importance of identifying asymptomatic cases for effective public health strategies.Elsevier established a free COVID-19 resource center in January 2020, offering information in English and Mandarin. The center is hosted on Elsevier Connect, and Elsevier grants permission to freely share its COVID-19 research in PubMed Central and other repositories. A letter to the editor estimates the asymptomatic ratio of COVID-19 infections using data from Japanese nationals evacuated from Wuhan. By February 6, 2020, 565 citizens were evacuated, with 63 (11.2%) showing symptoms upon arrival. RT-PCR testing revealed 4 asymptomatic and 9 symptomatic positive cases. Using Bayes' theorem, the asymptomatic ratio was calculated as 30.8% (95% CI 7.7–53.8%). The study suggests that less than half of infected individuals may be asymptomatic, slightly lower than the 56–80% estimated for influenza. The study acknowledges limitations, including age-related heterogeneity and a small sample size. Further research is needed to better understand asymptomatic infections and guide epidemic control. The authors declare no conflict of interest and received funding from various Japanese institutions. The study uses data from evacuated passengers, providing insights into asymptomatic viral shedding. The findings highlight the importance of identifying asymptomatic cases for effective public health strategies.