逆天“雄文”——如果我们比科学家想的更接近完成群体免疫（机翻对照版）

来源：纽约时报

（以下内容为原文对照网页机翻，欢迎指正）

《What if ‘Herd Immunity’ Is Closer Than Scientists Thought?》

In what may be the world’s most important math puzzle, researchers are trying to figure out how many people in a community must be immune before the coronavirus fades.

在这个可能是世界上最重要的数学难题中，研究人员正试图找出在冠状病毒消失之前，一个社区中有多少人必须免疫。

By Apoorva Mandavilli

Aug. 17, 2020

We’ve known from the beginning how the end will arrive. Eventually, the coronavirus will be unable to find enough susceptible hosts to survive, fading out wherever it briefly emerges.

我们从一开始就知道结局会怎样。最终，冠状病毒将无法找到足够的易受感染的宿主存活，在短暂出现的地方逐渐消失。

To achieve so-called herd immunity — the point at which the virus can no longer spread widely because there are not enough vulnerable humans — scientists have suggested that perhaps 70 percent of a given population must be immune, through vaccination or because they survived the infection.

为了实现所谓的群体免疫——由于没有足够的易受感染的人类，病毒不能再广泛传播——科学家们建议，一个给定的人口中，可能有70%必须通过接种疫苗或是因为他们在感染后幸存下来，而获得免疫。

Now some researchers are wrestling with a hopeful possibility. In interviews with The New York Times, more than a dozen scientists said that the threshold is likely to be much lower: just 50 percent, perhaps even less. If that’s true, then it may be possible to turn back the coronavirus more quickly than once thought.

现在一些研究人员正在努力寻找一种有希望的可能性。在接受《纽约时报》采访时，十几位科学家表示，这个门槛可能要低得多：只有50%，甚至可能更低。如果这是真的，那么冠状病毒就有可能比以前想象的更快地逆转。

The new estimates result from complicated statistical modeling of the pandemic, and the models have all taken divergent approaches, yielding inconsistent estimates. It is not certain that any community in the world has enough residents now immune to the virus to resist a second wave.

新的估计值来自于对大流行的复杂统计建模，而且这些模型都采用了不同的方法，产生了不一致的估计值。目前还不确定世界上是否有足够的居民对该病毒免疫，以抵抗第二波。

But in parts of New York, London and Mumbai, for example, it is not inconceivable that there is already substantial immunity to the coronavirus, scientists said.

但科学家说，例如，在纽约、伦敦和孟买的部分地区，人们已经对冠状病毒有了实质性的免疫力，这并不是不可想象的。

“I’m quite prepared to believe that there are pockets in New York City and London which have substantial immunity,” said Bill Hanage, an epidemiologist at the Harvard T.H. Chan School of Public Health. “What happens this winter will reflect that.”

“我完全准备好相信，在纽约市和伦敦，有一些地区拥有大量的免疫力，”哈佛大学T.H.Chan公共卫生学院的流行病学家Bill Hanage说。“今年冬天发生的事情将反映这一点。”

“The question of what it means for the population as a whole, however, is much more fraught,” he added.

他补充道：“然而，这对整个人口意味着什么的问题更令人担忧。”

Herd immunity is calculated from the epidemic’s so-called reproductive number, R0, an indicator of how many people each infected person spreads the virus to.

群体免疫是根据流行病的所谓生殖数R0计算的，R0是每个受感染者将病毒传播给多少人的指标。（这里设计一些专业术语，我确定网页机翻是有问题的）

The initial calculations for the herd immunity threshold assumed that each community member had the same susceptibility to the virus and mixed randomly with everyone else in the community.

群体免疫阈值的初始计算假设每个社区成员对病毒的易感性相同，并随机与社区中的其他人混合。

“That doesn’t happen in real life,” said Dr. Saad Omer, director of the Yale Institute for Global Health. “Herd immunity could vary from group to group, and subpopulation to subpopulation,” and even by postal codes, he said.

耶鲁大学全球卫生研究所所长萨阿德·奥马尔博士说：“现实生活中不会发生这种情况。”。他说：“群体免疫可能因群体而异，亚群体也可能因群体而异”，甚至按邮政编码（这里不知道如何翻译，有一个原文链接，标题是《检测抗SARS冠状病毒2的中和抗体以确定苏格兰献血者在2020年3月至5月的人群接触情况》Detection of neutralising antibodies to SARS coronavirus 2 to determine population exposure in Scottish blood donors between March and May 2020）也不尽相同。

For example, a neighborhood of older people may have little contact with others but succumb to the virus quickly when they encounter it, whereas teenagers may bequeath the virus to dozens of contacts and yet stay healthy themselves. The virus moves slowly in suburban and rural areas, where people live far apart, but zips through cities and households thick with people.

例如，一个社区的老年人可能很少与他人接触，但当他们遇到病毒时会很快死亡，而青少年可能会将病毒传给几十个接触者，但他们自己却保持健康。这种病毒在郊区和农村地区传播缓慢，在那里人们住得很远，但在城市和人口稠密的家庭中传播。

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最新消息：冠状病毒爆发

更新

美国大学校园与冠状病毒恐惧、疫情爆发和抗议活动作斗争。

对于中小学生和教职员工来说，这是一个艰难的返校季节。

数据报告问题正在爱荷华州和其他地方引起混乱。

更多现场报道

Once such real-world variations in density and demographics are accounted for, the estimates for herd immunity fall. Some researchers even suggested the figure may be in the range of 10 to 20 percent, but they were in the minority.

一旦考虑到现实世界中密度和人口统计的变化，对群体免疫的估计就会下降。一些研究人员甚至认为这个数字可能在10%到20%之间，但他们是少数。

Assuming the virus ferrets out the most outgoing and most susceptible in the first wave, immunity following a wave of infection is distributed more efficiently than with a vaccination campaign that seeks to protect everyone, said Tom Britton, a mathematician at Stockholm University.

斯德哥尔摩大学的数学家汤姆布里顿说，假设病毒在第一波中找到了最外向、最易受感染的人，那么在一波感染之后，免疫系统的分布比寻求保护每个人的疫苗接种活动更有效。

His model puts the threshold for herd immunity at 43 percent — that is, the virus cannot hang on in a community after that percentage of residents has been infected and recovered.

他的模型将群体免疫的阈值设定为43%——也就是说，在这一比例的居民被感染并恢复后，病毒就不能在社区中持续存在。

（拓展阅读：瑞典“群体免疫”失败！专家轻轻认个错——后沙月光）

Still, that means many residents of the community will have been sickened or have died, a high price to pay for herd immunity. And experts like Dr. Hanage cautioned that even a community that may have reached herd immunity cannot afford to be complacent.

不过，这意味着该社区的许多居民将生病或死亡，这是为群体免疫付出的高昂代价。像汉奇博士这样的专家警告说，即使是一个可能已经达到群体免疫的群体，也不能自满。

The virus may still flare up here and there, even if its overall spread is stymied. It’s also unclear how long someone who has recovered may be immune, and for how long.

即使病毒的整体传播受到阻碍，它仍可能到处爆发。目前还不清楚恢复的人能免疫多久，以及免疫多久。

​Virus-Resistant Communities?

抗病毒社区？

The coronavirus crashed this year’s Purim celebrations in the Orthodox Jewish neighborhoods of New York City, tearing through the parades and masquerades in Brooklyn on March 9 and 10.

冠状病毒摧毁了今年在纽约市东正教犹太社区举行的普瑞姆庆祝活动，3月9日和10日在布鲁克林的游行和化装舞会被摧毁。

Schools and synagogues soon shut down to quell the spread, but it was too late. By April, thousands in the Brooklyn communities were infected, and hundreds had died.

学校和犹太教堂很快就关闭了，以平息蔓延，但为时已晚。到今年4月，布鲁克林社区有数千人被感染，数百人死亡。

“It’s like a black hole in my memory because of how traumatic it was,” said Blimi Marcus, a nurse practitioner who lives in Borough Park, which was hit hard by the virus.

“这就像是我记忆中的一个黑洞，因为它造成那么多的创伤，”布里米·马库斯说，她是一名护士，住在受到病毒重创的伯勒公园。

But all that has changed now, Ms. Marcus added: “The general feeling is one of complacency, that somehow we’ve all had it and we’re safe.”

但现在一切都变了，马库斯女士补充道：“人们普遍的感觉是一种自满，不知何故我们都有过这种感觉，而且我们很安全。”

CORONAVIRUS SCHOOLS BRIEFING: The pandemic is upending education. Get the latest news and tips as students go back to school.

冠状病毒学校简介：大流行正在颠覆教育。当学生们回到学校时，获取最新的新闻和提示。

Is it possible that some of these communities have herd immunity? In some clinics, up to 80 percent of people tested had antibodies to the virus. The highest prevalence was found among teenage boys.

这些社区中有没有可能有群体免疫？在一些诊所，高达80%的受检者都有病毒抗体。青少年中患病率最高。

But people at clinics are more likely to be showing symptoms and therefore more likely to be infected, said Wan Yang, an epidemiologist at Columbia University’s Mailman School of Public Health in New York. Random household surveys would probably find lower rates — but still well above the 21 percent average reported for New York City, she said.

但纽约哥伦比亚大学梅尔曼公共卫生学院的流行病学家WanYang说，诊所里的人更容易出现症状，因此更容易被感染。她说，随机的家庭调查可能会发现较低的比率，但仍远高于纽约市21%的平均水平。

Researchers in Mumbai conducted just such a random household survey, knocking on every fourth door — or, if it was locked, the fifth — and took blood for antibody testing. They found a startling disparity between the city’s poorest neighborhoods and its more affluent enclaves. Between 51 and 58 percent of residents in poor areas had antibodies, versus 11 to 17 percent elsewhere in the city.

孟买的研究人员进行了这样一个随机的家庭调查，每敲一次门——如果门是锁着的，就敲第五扇门——然后抽血进行抗体检测。他们发现，该市最贫穷的社区与较富裕的飞地之间存在着惊人的差距。在贫困地区，51%到58%的居民有抗体，而在城市其他地方，这一比例为11%到17%。

The lowest-income residents are packed tightly together, share toilets, and have little access to masks. “These factors contributed to a silent infection spread,” said Dr. Jayanthi Shastri, a microbiologist at Kasturba Hospital in Mumbai who led the work.

收入最低的居民挤在一起，共用厕所，几乎没有口罩。负责这项研究的孟买卡斯图巴医院的微生物学家贾扬蒂·沙斯特里博士说：“这些因素促成了无声的感染传播。”。

Most researchers are wary of concluding that the hardest-hit neighborhoods of Brooklyn, or even those in blighted areas of Mumbai, have reached herd immunity or will be spared future outbreaks.

大多数研究人员对结论持谨慎态度，认为布鲁克林受灾最严重的社区，甚至孟买疫区的居民区，已经达到群体免疫，或将不会在未来爆发。

But models like Dr. Britton’s hint that it’s not impossible. Other researchers have suggested, controversially, that herd immunity can be achieved at rates of immunity as low as 10 or 20 percent — and that entire countries may already have achieved that goal.

但是像布里顿博士这样的模型暗示这并非不可能。另一些研究人员提出，有争议的是，群体免疫可以在低至10%或20%的免疫率下实现，而且整个国家可能已经实现了这一目标。

Criticism trailed Sunetra Gupta, a theoretical epidemiologist at Oxford University, after a widely circulated interview in which she said that London and New York may already have reached herd immunity because of variability among people, combined with a theoretical immunity to common cold coronaviruses that may protect against the new one.

牛津大学的理论流行病学家Sunetra Gupta在一次广为流传的采访中说，伦敦和纽约可能已经达到群体免疫，因为人之间的变异性，再加上对普通感冒冠状病毒的理论免疫力，可以抵御新的感冒冠状病毒。

“That could be the explanation for why you don’t see a resurgence in places like New York,” she said.

她说：“这可能就是为什么在纽约等地看不到复苏的原因。”

Most experts reject that notion. Several studies have shown that certain immune cells produced following infection with seasonal coronaviruses may also recognize the new coronavirus.

大多数专家反对这种观点。一些研究表明，感染季节性冠状病毒后产生的某些免疫细胞也可能识别这种新的冠状病毒。

But “where is the evidence that it’s protective?” asked Natalie Dean, a biostatistician at the University of Florida.

但是“哪里有证据证明它是保护性的？佛罗里达大学的生物统计学家娜塔莉·迪安问道。

The Coronavirus Outbreak ›Frequently Asked Questions

（这里是一段新冠防护指南，直接略过）

These cities have not returned to pre-pandemic levels of activity, other experts noted.

其他专家指出，这些城市尚未恢复到大流行前的活动水平。

“We are still nowhere near back to normal in our daily behavior,” said Virginia Pitzer, a mathematical epidemiologist at the Yale School of Public Health. “To think that we can just stop doing all that and go back to normal and not see a rise in cases I think is wrong, is incorrect.”

耶鲁大学公共卫生学院的一位数学流行病学家弗吉尼亚·皮策说：“我们的日常行为还远远没有恢复到正常水平。”。“认为我们可以停止这一切，回到正常状态，不会看到案件上升，我认为这是错误的，是不正确的。”

A second wave might also hit groups or neighborhoods that were spared by the first, and still wreak havoc, she said. Immunity is a patchwork quilt in New York, for instance: Antibodies were present in 68 percent of people visiting a clinic in the Corona neighborhood of Queens, for instance, but in just 13 percent of those tested at a clinic in the Cobble Hill section of Brooklyn.

她说，第二波可能也会袭击到第一次袭击中幸免于难的群体或社区，而且仍然会造成严重破坏。例如，在纽约，免疫力是一张拼凑而成的被子：例如，在皇后区科罗纳社区的诊所就诊的人中，有68%的人存在抗体，但在布鲁克林科布布尔山地区的一家诊所接受测试的人中，只有13%的人有抗体。

But another group, led by the mathematician Gabriela Gomes of the University of Strathclyde in Britain, accounted for variations within a society in its model and found that Belgium, England, Portugal and Spain have herd immunity thresholds in the range of 10 to 20 percent.

但是另一个由英国斯特拉斯克莱德大学的数学家加布里埃拉·戈麦斯领导的研究小组在其模型中解释了一个社会内部的差异，发现比利时、英国、葡萄牙和西班牙的群体免疫阈值在10%到20%之间。

“At least in countries we applied it to, we could never get any signal that herd immunity thresholds are higher,” Dr. Gomes said. “I think it’s good to have this horizon that it may be just a few more months of pandemic.”

戈麦斯博士说：“至少在我们应用它的国家，我们永远无法得到任何信号表明群体免疫阈值更高。”。“我认为这是一个好的前景，它可能只是几个月的大流行。”

Other experts urged caution, saying these models are flawed, as all models are, and that they oversimplify conditions on the ground.

其他专家敦促谨慎行事，称这些模型和所有模型一样都有缺陷，它们过分简化了实际情况。

Jeffrey Shaman, an epidemiologist at Columbia University, said it wasn’t clear to him that Dr. Gomes’s model offered only one possible solution. And he was suspicious of the big ranges among the four countries.

哥伦比亚大学的流行病学家杰弗里·沙曼说，他不清楚戈麦斯博士的模型只提供了一种可能的解决办法。他对这四个国家之间的巨大差距表示怀疑。

“I think we’d be playing with fire if we pretended we’re done with this,” Dr. Shaman said.

沙曼博士说：“我认为如果我们假装已经结束了这一切，那我们就是在玩火。”

The new models offer food for thought, he and other experts said, but should not be used to set policy.

他和其他专家说，新模式提供了思考的素材，但不应用于制定政策。

“Mathematically, it’s certainly possible to have herd immunity at these very, very low levels,” said Carl Bergstrom, an infectious disease expert at the University of Washington in Seattle. “Those are just our best guesses for what the numbers should look like.”

西雅图华盛顿大学传染病专家Carl Bergstrom说：“从数学上讲，在这些非常非常低的水平上，群体免疫是有可能的。”。“这些只是我们对数字应该是什么样子的最好猜测。”

“But,” he added, “they’re just exactly that, guesses.”

“但是，”他补充道，“他们只是猜测而已。”

Imperfect Immunity

不完全豁免

But what about immunity at levels lower than those needed for herd immunity?

但是低于群体免疫所需水平的免疫力呢？

“Definitely the disease would not spread as well if it gets back into New York,” said Joel Miller, a mathematical modeler at La Trobe University in Australia. “The same level of behavior change will have more effect on the disease now than it did four months ago.”

澳大利亚拉筹伯大学（La Trobe University）的数学模型师乔尔·米勒（Joel Miller）说：“如果疾病回到纽约，它肯定不会传播得很好。”“与四个月前相比，同样程度的行为改变对疾病的影响将更大。”

Thinking of a city or country as composed of subgroups, demarcated by age, race and level of social activity, might also help governments protect those with the least immunity.

把一个城市或国家看作是由年龄、种族和社会活动水平划分的亚群体，也可能有助于政府保护那些免疫力最低的人。

That perspective also might help put a renewed focus on groups who require the higher levels of immunity, because of greater exposure levels and other inequities, including Black and Latino residents, said Dr. Manoj Jain, an infectious disease expert at Emory University. “That’s where this info is very useful,” he said.

埃默里大学传染病专家马诺杰·贾恩博士说，这种观点也可能有助于重新关注那些需要更高免疫力水平的群体，因为他们的接触水平更高，还有其他不平等，包括黑人和拉丁美洲居民。“这就是这些信息非常有用的地方，”他说。

The models also suggest a vaccination strategy: Rather than uniformly vaccinate all groups, governments could identify and immunize those most likely to be exposed in “superspreader” events.

这些模型还提出了一种疫苗接种策略：政府可以识别并免疫那些最有可能在“超级传播者”事件中暴露的人群，而不是对所有人群进行统一的疫苗接种。

“Getting those people vaccinated first can lead to the greatest benefit,” said Dr. Michael Mina, an immunologist at Harvard University. “That alone could lead to herd immunity.”

哈佛大学的免疫学家迈克尔米纳博士说：“首先让这些人接种疫苗可以带来最大的益处。”“单凭这一点就可能导致群体免疫。”

Vaccination schemes for other pathogens have successfully exploited this approach. For example, when children were given the pneumococcal vaccine in the early 2000s, rates of bacterial pneumonia in the elderly rapidly dropped because of a “herd effect.”

其他病原体的疫苗接种计划已经成功地利用了这一方法。例如，2000年代初，当儿童接种肺炎球菌疫苗时，由于“羊群效应”，老年人细菌性肺炎的发病率迅速下降

Vaccines that offer just 50 percent protection are considered to be moderately effective, but at that efficiency, even a low herd immunity target would require that a large proportion of the population be immunized, Dr. Bergstrom noted.

Bergstrom博士指出，只提供50%保护的疫苗被认为是中等有效的，但在这种效率下，即使是低群体免疫目标，也需要很大比例的人群接受免疫。

If there are early reports of side effects that may scare away some people, he said, “we’d do well to start thinking about all that now.”

他说，如果早期有副作用的报告可能会吓跑一些人，“我们最好现在就开始考虑这些问题。”

Back in Brooklyn, fewer than 1 percent of people tested at neighborhood clinics over the past eight weeks were infected with the virus. But there are still handfuls of cases, Ms. Marcus said, adding that her 10-year-old niece was in quarantine because a counselor at her day camp had tested positive.

回到布鲁克林，在过去的8周里，在社区诊所接受检查的人中只有不到1%感染了这种病毒。马库斯说，但仍有大量病例，她还说，她10岁的侄女正处于隔离状态，因为她日间训练营的一名顾问检测呈阳性。

“Sometimes that’s all you need, right?” she said. “I’m still hoping we don’t see what we had in March and April, but I’m not so sure that we’ve seen the end of it.”

“有时候你只需要这些，对吗？她说。“我还是希望我们不要看到三四月份的情况，但我不太确定我们是否看到了结局。”