From https://www.wsj.com/articles/so-where-did-the-virus-come-from-11590756909 https://www.wsj.com/articles/so-where-did-the-virus-come-fro...: > New re­search

From https://www.wsj.com/articles/so-where-did-the-virus-come-from-11590756909 https://www.wsj.com/articles/so-where-did-the-virus-come-fro...: > New re­search has deep­ened, rather than dis­pelled, the mys­tery sur­round­ing the ori­gin of the coro­n­avirus re­spon­si­ble for Covid-19. Bats, wildlife mar­kets, pos­si­bly pan­golins and per­haps lab­o­ra­to­ries may all have played some role, but the sim­ple story of an an­i­mal in a mar­ket in­fected by a bat that then in­fected sev­eral hu­man be­ings no longer looks cred­i­ble. > A study pub­lished in early May by sci­en­tists at the Broad In­sti­tute in Cam­bridge, Mass., and at the Uni­ver­sity of British Co­lumbia has un­cov­ered an un­usual fea­ture of the virus’s re­cent de­vel­op­ment: It has evolved too slowly. The genomes of viruses sam­pled from cases dur­ing the SARS epi­demic of 2002-2003 showed rapid evo­lu­tion­ary change dur­ing the early months of the epi­demic, as the virus adapted to its new host, fol­lowed by much slower change later. By con­trast, sam­ples taken from re­cent cases of the new coro­n­avirus, SARS-CoV-2, have com­par­a-tively few ge­netic sub­sti­tu­tions com­pared with an early case from De­cem­ber. > The au­thors, Shing Hei Zhan, Ben­jamin De­v­er­man and Yu­jia Alina Chan, write: “We were sur­prised to find that SARS-CoV-2 ex­hibits low ge­netic di­ver­sity in con­trast to SARS-CoV, which har­bored con­sid­er­able ge­netic di­ver­sity in its early-to-mid epi­demic phase.” This im­plies, they ar­gue, that “by the time SARS-CoV-2 was first de­tected in late 2019, it was al­ready pre-adapted to hu­man trans­mis­sion to an ex­tent sim­i­lar to late epi­demic SARS-CoV.” This is po­ten­tially very good news: Be­cause the virus is rel­a­tively sta­ble ge­net­i­cally, a vac­cine that works against it, if we’re able to de­velop one, will be more likely to work against all strains. > The same study seems to rule out the pos­si­bil­ity that in­fected an­i­mals at the Hua­nan Seafood Mar­ket in Wuhan trans­mit­ted the virus to sev­eral hu­man be­ings, as some have sug­gested as a point of ori­gin. The Chi­nese au­thor­i­ties have now con­firmed that no an­i­mal sam­ples from the mar­ket were in­fected. This sug­gests that a sin­gle per­son brought a virus that was al­ready adept at hu­man trans­mis­sion to the mar­ket and in­fected oth­ers.