[1] Zhou L, Yao LS, Hao P, Li C, Zhao QL, Dong HL, et al. COVID-19 cases spread through the K350 train — Jilin and Heilongjiang Provinces, China, January 2021. China CDC Wkly 2021. http://dx.doi.org/10.46234/ccdcw2021.026CrossRef
[2] Kim MC, Cui CG, Shin KR, Bae JY, Kweon OJ, Lee MK, et al. Duration of culturable SARS-CoV-2 in hospitalized patients with Covid-19. N Engl J Med 2021. http://dx.doi.org/10.1056/NEJMc2027040CrossRef