过去两年来，许多国家对早期新冠肺炎疫情取得了新发现，引发学界对新冠病毒起源和传播的新思考。 Scientists from various countries have found the existence of the novel coronavirus earlier than the first reported cases in China amid international efforts to piece together the puzzle of the COVID-19 origins. At least nine recent studies have identified the virus in the U.S., Europe, Brazil and Japan, a sign that these pathogens emerged and circulated earlier than previously known. 美国 美国最新研究发现，美国多地采集的血液样本中检测到新冠病毒抗体，证明早在2019年12月新冠病毒已在美国本土以低速率进行传播。 在美国国立卫生研究院(NIH)发起的一项名为“我们所有人”的研究中，研究人员在2020年初采集了美国各地共24000份血液样本。检测结果显示，至少有9人的血液样本中出现了新冠病毒抗体，其中日期最早的来自于1月7日在伊利诺伊州采集的样本，随后在1月8日从马萨诸塞州、2月3日从威斯康星州、2月15日从宾夕法尼亚州和3月6日在密西西比州收集的标本中，研究人员均检测到抗体。 因感染新冠病毒后需要大约两周的时间产生抗体，此次美国国立卫生研究院的研究证明，在美国疫情正式暴发(2020年)前，早在2019年12月新冠病毒已在美国本土以低速率进行传播。 A study published in June 2021 by the U.S. National Institutes of Health (NIH) was the latest and largest (in scale) one to suggest that the new coronavirus popped up in the U.S. in December 2019, weeks before cases were first recognized by health officials. Scientists at the NIH found antibodies to the novel coronavirus, known as SARS-CoV-2, in nine blood samples out of more than 24,000 people who gave blood between January 2 and March 18, 2020. Antibodies usually take about 14 days to develop. 根据在线发表于《临床传染病》杂志上的研究，美国疾病控制与预防中心（CDC）科学家在美国红十字会从全美9个州的居民那里收集的7389份血液中，发现了106份新冠病毒感染证据。这些发现强有力地表明，新冠病毒早在公共卫生当局和研究人员意识到之前就已经在世界范围内传播，颠覆了人们最初对这种病毒出现的时间和速度的认知。 A CDC-led study published in December 2020 that analyzed 7,000 blood samples suggested the virus infected some Americans as early as the middle of December 2019. In the study published in the journal Clinical Infectious Diseases in November 2020, CDC researchers tested blood samples from 7,389 routine blood donations collected by the American Red Cross from December 13, 2019 to January 17, 2020 for antibodies. The blood tests found SARS-CoV-2 antibodies in 106 of 7,389 blood donors. 法国 医学期刊《国际抗菌剂杂志》网站去年5月3日刊登的一篇短篇通讯论文，主张新冠病毒2019年12月底已在法国传播。 论文中显示，研究人员选取了14个在2019年12月2日到2020年1月16日期间因类流感疾病（ILI）入住重症监护室的病例，并将其鼻（咽）拭子从零下80摄氏度的冷藏环境中取出，于今年4月6日到4月9日重新进行新冠病毒核酸检测。值得注意的是，这些病例在入院时接受FilmArray快速呼吸道病原体检测结果呈阴性。研究人员此次发现一名42岁男子的样本新冠病毒检测呈阳性。 A hospital in Paris, France revisited test results of a group of ICU patients with respiratory infections that tested negative for flu and other kinds of coronaviruses in December 2019 and January 2020, but a swab taken from a male patient on December 27, 2019 tested positive for the coronavirus, which is a month before the first French cases were confirmed. This means the virus may have circulated in Europe almost a month earlier than previously thought. 巴西 巴西圣卡塔琳娜联邦大学去年7月2日发表研究报告说，由该校领衔的一个研究小组在圣卡塔琳娜州首府弗洛里亚诺波利斯市2019年11月27日采集的废水样本中检测到了新冠病毒的遗传物质。这比美洲报告首例新冠病例的时间提前了约2个月，比巴西报告首例新冠病例的时间提前了约3个月。 A Brazilian research team found samples of the novel coronavirus in the sewer system of the southern city of Florianopolis back in late November 2019, three months before the first coronavirus case was officially recorded in the country on February 26, 2020. 意大利 意大利高等卫生研究院去年6月18日发表公报说，新冠病毒可能在2019年12月就已出现在意大利北部地区。公报说，该研究院环境与水质卫生监测等部门专家分析了2019年10月至去年2月间收集的40个城市废水样本，结果在2019年12月18日取样的米兰市和都灵市废水中检测到了新冠病毒的遗传物质。 SARS-CoV-2 was detected in the samples collected from Milan and Turin sewage in December 2019, according to a study published by the Italian National Institute of Health. The study suggests the virus already existed in wastewater collected from the entrance of treatment plants in northern Italy before the country's first coronavirus case was reported. 米兰癌症研究中心——国家肿瘤研究所的科学家们在7月19日发表的一篇新论文中写道，两个实验室对新冠疫情暴发前采集的少量血液样本进行了重新检测。结果表明，存在通常会在新冠病毒感染后观察到的抗体。 据报道，意大利研究人员最初在新冠大流行前筛查了959名肺癌患者。2020年，他们再次测试了这些样本，寻找与冠状病毒相关的抗体，并表示他们发现了感染的痕迹。 A study by the National Cancer Institute (INT) of the Italian city of Milan published in November 2020 found blood samples taken in September 2019 showed the presence of antibodies against the SARS‑CoV‑2 virus. "What we noticed, and it was unexpected, we found more than 10 percent of the samples presenting antibodies against the COVID-19 virus," INT biologist Gabriella Sozzi told CGTN. "This finding seems to tell us that the SARS‑CoV‑2 virus was probably circulating at a low level in Italy before the outbreak that we had in February." The Italian researchers' findings, published by the INT's scientific magazine Tumori Journal, show that 111 out of 959 healthy volunteers enrolled in a lung cancer screening trial between September 2019 and March 2020 had developed coronavirus antibodies. 意大利米兰大学牵头的一个国际研究团队今年1月在《英国皮肤病学杂志》上发布报告说，他们从该国一名年轻女性皮肤病患者2019年11月10日的活检样本中发现了新冠病毒基因序列。这一结果将意大利“零号病人”出现时间再次提前到2019年11月。意大利首次报告新冠确诊病例是去年1月30日，报告本土病例是去年2月21日。 Clues to COVID-19 origins include an anonymous skin sample in Italy from a 25-year-old Milan resident who in November 2019 visited a hospital with a sore throat and skin lesions. She left behind a skin sample that in two tests conducted more than six months later yielded traces of the virus, according to research published in January by the British Journal of Dermatology. 西班牙 西班牙巴塞罗那大学去年6月26日发布公报说，该校领导的一个研究小组分析了2018年1月至2019年12月的废水样本，结果发现2019年3月12日采集的废水样本新冠病毒核酸检测呈阳性，不过病毒水平非常低。这意味着新冠病毒可能当时已在巴塞罗那存在，该时间点要比全球报告首例新冠确诊病例的时间提前很多。 A study published in June 2020 by Spanish virologists at the University of Barcelona discovered traces of the virus in samples of wastewater from Barcelona collected in March 2019, 10 months before its first reported coronavirus case. The team had been testing sewage since April 2020 in order to identify new potential outbreaks of the virus. "These results, sent to a high impact journal and published in the archive medRxiv, suggest the infection was present before knowing about any case of COVID-19 in any part of the world," the statement said. "Those infected could have been diagnosed with flu in primary care by mistake, contributing to the community transmission before the public health authorities took measures." 日本 厚生劳动大臣加藤胜信今年5月在一次记者会上提及，在2019年1至3月采集的500份血液样本中，有2份新冠病毒抗体检测结果呈阳性。但专家表示，因检测存在误判可能，且不同试剂盒检测结果也有差异，以此次少人数的检测结果判定抗体携带率并不妥当。 Two positive results were found in an investigation by Japan's Ministry of Health, Labor and Welfare among 500 blood donation samples collected from January to March in 2019 in Japan's Koshinetsu region. The health ministry said there was a high probability that "false positives" occurred within a certain percentage of people who were not actually infected. The studies with COVID-19-positive results are an example of the scattered clues about the pandemic's early days that could help determine how long the virus had been circulating the world before a cluster of cases erupted in central China's Wuhan in December 2019. 推荐阅读：CGTN智库全球网络民意调查：83.1%网民支持应对美国进行溯源调查 粉碎标题党 | “实验室泄漏论”卷土重来，外媒如何推波助澜？