Strategies to trace back the origin of COVID-19

In spite of considerable research advancements on SARS-CoV-2, the origin of the virus is yet ambiguous. Chinese authorities originally announced that the first infection case was reported on December 31, 2019, and many of the initial cases were linked directly to Huanan seafood market in Wuhan, in the Hubei province.5 Apart from fish and seafood, the market also sold domestic and wild animals. Thirty-three of the 585 environmental samples collected from the market were found to contain the novel coronavirus, according to China CDC. The hypothesis that the outbreak originated at the market, with its initial transmission from live animals to human beings followed by rapid human-to-human transmission, is suggested to be most likely and convincing.6 However, another recent study claimed that the first patient, diagnosed on December 1, 2019, was never exposed to the market.7 Thus, origin of the disease still remains a puzzle unresolved. Identification and subsequent elimination of the zoonotic source appears to be the most imperative and demanding task at present to prevent further events of viral spillover at the animal-human interface.8 The seafood market was closed on January 1, 2020, and existing animals had been cleaned up, making it very difficult to identify the intermediate hosts. However, tracing the source of the virus might be targeted from the following perspectives: