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| In recent days, the world has watched with curiosity and growing alarm as scientists in the U.K. have described a newly identified variant of the coronavirus that appears to be more contagious than, and genetically distinct from, more established variants. Initial studies of the new variant prompted Prime Minister Boris Johnson to tighten restrictions over Christmas, and spurred officials in the Netherlands, Germany and other European countries to ban travel from the U.K. |
| 最近几天，英国科学家揭示了一种新发现的新冠病毒变种，它在基因上不同于更成熟的变体，而且似乎更具传染性，全世界对此充满好奇，并且警惕性越来越高。对新变种的初步研究促使首相鲍里斯·约翰逊(Boris Johnson)加强了圣诞节限制，并刺激荷兰、德国和其他欧洲国家对英国宣布了旅行限制。 |
| The new variant is now the focus of intense debate and analysis. Here’s some of what scientists have learned so far. |
| 现在，新的变种成为了激烈辩论和分析的焦点。以下是到目前为止科学家们所了解到的。 |
| Is the U.K. variant some kind of new supervirus? |
| 英国变种是某种新型的超级病毒吗？ |
| No. It’s just one variation among many that have arisen as the coronavirus SARS-CoV-2 has spread around the world. Mutations arise as the virus replicates, and this variant — known as B.1.1.7 — has acquired its own distinctive set of them. |
| 不是，这只是随着新冠病毒SARS-CoV-2在世界范围内传播而出现的众多变种之一。病毒复制时会产生突变，而这种被称为B.1.1.7的变种，已经获得了独有的一组突变。 |
| What is unusual about it? |
| 它有什么不寻常的地方？ |
| The variant came to the attention of researchers in December, when it began to turn up more frequently in samples from parts of southern England. It turned out to have been collected from patients as early as September. |
| 这个变种在12月份引起了研究人员的注意，当时它在英格兰南部部分地区的样本中开始频繁出现。事实证明，早在9月就已从患者那里收集到了这种变种。 |
| When researchers took a close look at its genome, they were struck by the relatively large number of mutations — 23, all told — that it had acquired. Most mutations that arise in the coronavirus are either harmful to the virus or have no effect one way or another. But a number of the mutations in B.1.1.7 looked as if they could potentially affect how the virus spread. |
| 当研究人员仔细观察它的基因组时，他们被它已经获得的相对大量的突变（共23个）所震惊。新冠病毒中产生的大多数突变要么对该病毒有害，要么最终无效。但是B.1.1.7中的许多突变似乎都可能影响病毒的传播方式。 |
| Is it more contagious than other viruses? |
| 它比其他病毒更具传染力吗？ |
| It appears so. In preliminary work, researchers in the U.K. have found that the virus is spreading quickly in parts of southern England, displacing a crowded field of other variants that have been circulating for months. |
| 看起来是这样。在初步工作中，英国的研究者发现该病毒正在英国南部的部分地区迅速传播，取代了已经流行几个月的许多其他变种。 |
| However, a virus lineage becoming more common is not proof that it spreads faster than others. It could grow more widespread simply through luck. For instance, a variant might start out in the middle of a crowded city, where transmission is easy, allowing it to make more copies of itself. |
| 但是，病毒谱系变得越来越普遍并不能证明它的传播速度比其他变体更快。它的传播广泛可能只是靠运气。例如，一种变体可能始于一个拥挤的城市，在那里病毒易于传播，复制地更多。 |
| Still, the epidemiological evidence gathered so far from England does seem to suggest that this variant is very good at spreading. In places where it has become more common, the overall number of coronavirus cases is spiking. Neil Ferguson, an epidemiologist at Imperial College London, estimates that the variant has an increased transmission rate of 50 to 70 percent compared with other variants in the United Kingdom. |
| 尽管如此，到目前为止从英格兰收集到的流行病学证据似乎表明该变种非常擅长传播。在该病毒已经越来越普遍的地方，新冠病毒病例的总数正在飙升。伦敦帝国理工学院(Imperial College London)的流行病学家尼尔·弗格森(Neil Ferguson)估计，与英国的其他变种相比，该变种的传播率提高了50％至70％。 |
| Some scientists have raised the possibility that the increase in transmission is at least partly the result of how it infects children. Normally, children are less likely than teenagers or adults to get infected or pass on the virus. But the new variant may make children “as equally susceptible as adults,” said Wendy Barclay, government adviser and virologist at Imperial College London. |
| 一些科学家提出了传播增加的可能性至少部分是由于它感染儿童的方式。通常，儿童比青少年或成年人感染或传播新冠病毒的可能性要小。但是，伦敦帝国理工学院的政府顾问和病毒学家温迪·巴克莱(Wendy Barclay)说，新的变种可能会使儿童“与成年人一样易感”。 |
| To confirm that the variant truly is more contagious, researchers are now running laboratory experiments on it, observing up close how it infects cells. |
| 为了确认该变体确实具有更强的传染性，研究人员现在正在对其进行实验室研究，密切观察它是如何感染细胞的。 |
| Researchers have already used such experiments to investigate a mutant that arose earlier in the pandemic, called 614G. That variant proved to be more transmissible than its predecessors, studies in cell culture and animals found. |
| 研究人员使用这种实验对更早出现在大流行中的突变体614G进行过研究。在细胞培养和动物研究中，发现该变种比之前的变种更具传播性。 |
| But disciplined containment measures worked just as well against 614G as other variants. The same is likely true for B.1.1.7. “According to what we already know, it does not alter the effectiveness of social distancing, face masks, hand washing, hand sanitizers and ventilation,” Dr. Muge Cevik, an infectious disease specialist at the University of St. Andrews School of Medicine, said on Twitter. |
| 但是严格的防疫措施对于614G以及其他变体一样有效。对于B.1.1.7可能也是如此。圣安德鲁斯大学医学院(University of St. Andrews School of Medicine)传染病专家米盖·切维克(Muge Cevik)在推特上说：“根据我们已经知道的情况，保持社交距离、戴口罩、洗手、手部消毒液和通风的效果不会因它而改变。” |
| Does it cause more severe disease? |
| 它会导致更严重的疾病吗？ |
| There is no strong evidence that it does, at least not yet. But there is reason to take the possibility seriously. In South Africa, another lineage of the coronavirus has gained one particular mutation that is also found in B.1.1.7. This variant is spreading quickly through coastal areas of South Africa. And in preliminary studies, doctors there have found that people infected with this variant carry a heightened viral load — a higher concentration of the virus in their upper respiratory tract. In many viral diseases, this is associated with more severe symptoms. |
| 没有足够的证据表明它会，至少目前还没有。但是有理由认真考虑这个可能性。在南非，另一个谱系的新冠病毒出现了一种特殊的突变，该突变也在B.1.1.7中发现。那个变种正在南非沿海地区迅速传播。并且在初步研究中，那里的医生发现感染这种病毒的人携带的病毒量更高——病毒在其上呼吸道中的浓度更高。在许多病毒性疾病中，这与更严重的症状有关。 |
| Where did this unusual variant come from? |
| 这种不寻常的变异因何而来？ |
| That is now a question of intense debate. One possibility is that the variant gained its array of new mutations inside a special set of hosts. |
| 现在这是一个激烈争论的问题。一种可能性是，该变种在一组特殊宿主体内获得了一系列新突变。 |
| In a typical infection, people pick up the coronavirus and become infectious for a few days before showing symptoms. The virus then becomes less abundant in the body as the immune system marshals a defense. Unless patients suffer a serious case of Covid-19, they typically clear the virus completely in a few weeks at most. |
| 在典型的感染案例中，人们染上新冠病毒，感染几天后才会出现症状。当免疫系统进行防御时，病毒在体内的数量就会减少。除非患者出现了严重的新冠症状，不然他们通常最多在几周内就能将病毒完全清除。 |
| But sometimes the virus infects people with weak immune systems. In their bodies, the virus can thrive for months. Case studies on these immunocompromised people have shown that the virus can accumulate a large number of mutations as it replicates in their bodies for a long period of time. |
| 但有时免疫系统较弱的人会被病毒感染。在他们体内，病毒可以活跃数月之久。对这些免疫缺陷患者的病例研究表明，病毒长期在他们体内复制时，会积累大量突变。 |
| Over time, researchers have found, natural selection can favor mutant viruses that can evade the immune system. Researchers have also suggested that the evolution of the variant might have been additionally driven by medicine given to such patients. Some mutants might be able to withstand drugs such as monoclonal antibodies. |
| 研究人员发现，随着时间推移，自然选择有利于能够躲避免疫系统的变异病毒。研究人员还提出，病毒变异的进化可能是患者服用的药物所推动的。一些变种可能具备对单株抗体等药物的耐受能力。 |
| Other scientists have suggested that the virus could have gained new mutations by spreading through an animal population, like minks, before re-entering the human population. Such “animal reservoirs” have become a focus of intense interest as more animal infections have been detected. |
| 其他科学家提出，在病毒重新感染人群之前，可能通过在动物群体（如水貂）中传播而获得新的突变。随着越来越多的动物感染被发现，这样的“动物宿主”已经成为引发人们强烈关注的焦点。 |
| Is the variant already circulating in the U.S.? |
| 该变种已经在美国蔓延了吗？ |
| Not yet, as far as anyone knows. But that does not mean it hasn’t already reached the United States. British scientists have established a much stronger system to monitor coronaviruses for new mutations. It’s conceivable that someone traveling from the United Kingdom has brought it with them. Now that the world knows to look for the variant, it may turn up in more countries. |
| 据大家所知，目前还没有。但这不意味着它没有到达美国。英国科学家已经建立了一个更强大的系统来监测新冠病毒的新突变。可以想象，有从英国来的人将它带来的情况。现在全世界都知道要寻找这种变异，它可能会在更多国家出现。 |
| Will the variant render the new vaccines ineffective? |
| 这个变异会使新疫苗失效吗？ |
| No. Most experts doubt that it will have any great impact on vaccines, although it’s not yet possible to rule out any effect. |
| 不会。大多数专家都猜测它不会对疫苗产生重大影响，尽管尚不排除这种可能。 |
| The U.S. Food and Drug Administration has authorized two vaccines, one from Moderna and the other from Pfizer and BioNTech. Both vaccines create immunity to the coronavirus by teaching our immune systems to make antibodies to a protein that sits on the surface of the virus, called spike. The spike protein latches onto cells and opens a passageway inside. Antibodies produced in response to the vaccines stick to the tip of the spike. The result: The viruses can’t get inside. |
| 美国食品和药品监督管理局(U.S. Food and Drug Administration)已经批准了两种疫苗，一种由莫德纳(Moderna)生产，一种由辉瑞(Pfizer)和BioNTech生产。这两种疫苗都通过引导我们的免疫系统针对一种位于病毒表面被称为刺突的蛋白质制造抗体，来产生对新冠病毒的免疫力。这种刺突蛋白附着在细胞上，并在其内部打开通道。因疫苗产生的抗体会停留在刺突顶端。结果是：病毒无法进入细胞内部。 |
| It is conceivable that a mutation to a coronavirus could change the shape of its spike proteins, making it harder for the antibodies to gain a tight grip on them. And B.1.1.7’s mutations include eight in the spike gene. But our immune systems can produce a range of antibodies against a single viral protein, making it less likely that viruses can easily escape their attack. Right now, experts don’t think that the variant will be able to evade vaccines. To confirm that, researchers at the Walter Reed Army Institute of Research are analyzing the changes to the structure of its spike protein. |
| 可以想像，新冠病毒的一次突变可能会改变其刺突蛋白的形状，使抗体更难紧紧抓住它们。B.1.1.7的突变包括八个刺突基因。但我们的免疫系统可以产生一系列针对单一病毒蛋白质的抗体，使病毒不太可能轻易逃脱攻击。目前，专家们不认为该变种能躲避疫苗。为了证实这一点，沃尔特·里德陆军研究院(Walter Reed Army Institute of Research)的研究人员正在分析其刺突蛋白结构的变化。 |
| Dr. Moncef Slaoui, the head scientific adviser to Operation Warp Speed, the federal effort to deliver a vaccine to the American public, said that the new variant reported in Britain was unlikely to affect the efficacy of a vaccine. |
| 联邦政府致力于为美国公众提供疫苗的“曲速行动” 计划(Operation Warp Speed)的首席科学顾问蒙塞夫·斯劳伊(Moncef Slaoui)表示，英国报告的新变种不太可能影响疫苗的效力。 |
| At some point — “some day, somewhere” — a variant of the virus may make the current vaccine ineffective, he said, but the chance of that happening with this vaccine is very low. Nevertheless, he said, “we have to remain absolutely vigilant.” |
| 在某一刻——“某天在某个地方”——的某种病毒变种可能会使目前的疫苗失效，他说，但新冠疫苗出现这种情况的几率非常低。不管怎样，他表示，“我们都必须保持绝对警惕。” |
| But Kristian Andersen, a virologist at Scripps Research Institute, thinks it is too early to dismiss the risk to vaccines. If the U.K. variant evolved to evade the immune system in immunocompromised patients, those adaptations might help it avoid vaccines. The vaccines would not become useless, but they would become less effective. Fortunately, experiments are underway to test that possibility. |
| 但斯克里普斯研究所(Scripps Research Institute)的病毒学家克里斯蒂安·安德森(Kristian Andersen)认为，现在就排除疫苗的风险还为时过早。如果英国的变种进化到能躲避免疫缺陷患者的免疫系统，那这种适应性可能会帮助它躲避疫苗的效力。疫苗不会变得无用，但可能不再那么有效。幸运的是，现在已在进行测试这种可能性的实验。 |
| “We don’t know, but we’ll know soon,” Dr. Andersen said. |
| “我们还不知道结果，但很快就能知道了，”安德森博士说。 |
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