As we know from our experience with Covid-19, tracking down the source of a pandemic is incredibly difficult.
원문출처 : https://www.cnn.com/2022/06/18/world/plague-origins-science-newsletter-wt-scn/index.html
원문출처 : https://www.cnn.com/2022/06/18/world/plague-origins-science-newsletter-wt-scn/index.html