From://academic.oup.com/cid/advance-article/doi/10.1093/cid/ciaa1785/6012472 6park.com
       引起新冠肺炎病的SARS-CoV-2病毒于2019年12月在中国武汉首次发现，随后在全球范围内传播。美国在2020年1月发现了第一批病例。 6park.com
       为了确定在美国于2020年1月19日发现的第一个确诊病例之前血清中是否存在SARS-CoV-2反应抗体，美国红十字会从2019年12月13日至2020年1月17日收集的7,389份常规献血的残余样本，以及居住在九个州(加利福尼亚、康涅狄格州、爱荷华州、马萨诸塞州、密歇根州、俄勒冈州、罗得岛、华盛顿和威斯康星州)的献血者，进行了抗SARS-CoV-2抗体检测。用泛免疫球蛋白(PAN Ig)酶联免疫吸附试验(ELISA)检测IgG、IgM、微球化试验、Ig S1总酶联免疫吸附试验(ELISA)、受体结合域/ACE 2阻断活性试验。 6park.com
       在7,389份样品中，106份为PAN Ig反应。在这106个样本中，有90个可供进一步测试。其中84份具有中和活性，1份具有S1结合活性，1份具有受体结合域/ACE 2阻断活性>50%，提示存在抗SARS-CoV-2-反应性抗体。所有9个州都有反应性捐赠。 6park.com
       这些发现表明，SARS-CoV-2可能是在2020年1月19日前被引入美国的。

Serologic testing of U.S. blood donations to identify SARS-CoV-2-reactive antibodies: December 2019-January 2020 | Clinical Infectious Diseases | Oxford Academic 6park.com
Background
SARS-CoV-2, the virus that causes COVID-19 disease, was first identified in Wuhan, China in December 2019, with subsequent worldwide spread. The first U.S. cases were identified in January 2020. 6park.com
Methods
To determine if SARS-CoV-2 reactive antibodies were present in sera prior to the first identified case in the U.S. on January 19, 2020, residual archived samples from 7,389 routine blood donations collected by the American Red Cross from December 13, 2019 to January 17, 2020, from donors resident in nine states (California, Connecticut, Iowa, Massachusetts, Michigan, Oregon, Rhode Island, Washington, and Wisconsin) were tested at CDC for anti-SARS-CoV-2 antibodies. Specimens reactive by pan-immunoglobulin (pan Ig) enzyme linked immunosorbent assay (ELISA) against the full spike protein were tested by IgG and IgM ELISAs, microneutralization test, Ortho total Ig S1 ELISA, and receptor binding domain / Ace2 blocking activity assay. 6park.com
Results
Of the 7,389 samples, 106 were reactive by pan Ig. Of these 106 specimens, 90 were available for further testing. Eighty four of 90 had neutralizing activity, 1 had S1 binding activity, and 1 had receptor binding domain / Ace2 blocking activity >50%, suggesting the presence of anti-SARS-CoV-2-reactive antibodies. Donations with reactivity occurred in all nine states. 6park.com
Conclusions
These findings suggest that SARS-CoV-2 may have been introduced into the United States prior to January 19, 2020.