泛读：群体免疫对新冠病毒疫情真的有效吗？

Can herd immunity really protect us from coronavirus?

群体免疫真的能对抗新冠病毒吗？

2020年3月，英国宣布采取群体免疫的手段来对抗新冠病毒疫情。所谓群体免疫通俗一些说，就是让全国大部分人都感染新冠病毒，轻症的病人先不就医，二十通过身体免疫力与病毒对抗，产生抗体，获得免疫力，病情严重时，再求助当地的医疗组织治疗，从而使得全国的大部分人获得对新冠病毒的免疫力。这样的做法真的可行吗？牺牲2%的英国公民获得免疫力真的没有更好地办法了吗？我们一起来读读这篇国外的新闻是分析评论的。

The UK government is aiming to achieve herdimmunity as a way of tackling COVID-19. Herd immunity means enough people havingimmunity to a disease to stop it spreading. The UK government recently enacted itssecond phase of response to the COVID-19 pandemic: “delay”. According to ITV journalist Robert Peston, the government’s strategy to minimise the impact ofCOVID-19 “is to allow the virus to pass through the entire population so thatwe acquire herd immunity, but at a much delayed speed so that those who sufferthe most acute symptoms are able to receive the medical support they need, andsuch that the health service is not overwhelmed and crushed by the sheer numberof cases it has to treat at any one time”. At face value, this seems like asound strategy, but what exactly is herd immunity and can it be used to combatCOVID-19?

英国政府的目标是实现针对性的群体免疫，以解决COVID-19。群体免疫意味着足够的人对某种疾病具有免疫力以阻止其传播。英国政府最近制定了应对COVID-19大流行的第二阶段应对措施：“延迟”。根据ITV记者罗伯特·佩斯顿（Robert Peston）的说法，政府最大程度地减少COVID-19的影响的策略是“让病毒传播到整个人群，以便我们获得群体免疫力，但速度要慢得多，这样，那些遭受最严重症状的人就会 能够获得他们需要的医疗支持，并且不会在任何时候都要处理的大量病例中使医疗服务不堪重负。” 从表面上看，这似乎是一种明智的策略，但是群体免疫到底是什么，可以用来对抗COVID-19吗？

Our bodies fight infectious diseases through theactions of our immune systems. When we recover, we often retain animmunological memory of the disease that enables us to fight off that samedisease in the future. This is how vaccines work, creating this immune memory without requiring getting sick with the disease.

我们的身体通过免疫系统的作用抵抗传染病。当我们康复时，我们通常会保留对该疾病的免疫记忆，从而使我们能够在将来抵抗该疾病。疫苗就是这样工作的，无需引起疾病就可以创建这种免疫记忆。

Have you read?

This is what different countries are doingto stop coronavirus from spreading. If you have a new disease, such as COVID-19, that we don’t have a vaccine for and no one in the country has everbeen infected with, the disease will spread through the population. But if enoughpeople develop an immune memory, then the disease will stop spreading, even ifsome of the population is not immune. This is herd immunity, and it is a veryeffective way to protect the whole of a population against infectious disease.

你听说了吗？

这是不同国家为阻止冠状病毒扩散所做的工作。如果您患有我们没有疫苗的新疾病，例如COVID-19，并且该国从未有人感染过该疾病，那么该疾病将在整个人群中传播。但是，如果有足够多的人发展出免疫记忆，那么即使某些人群没有免疫力，疾病也会停止传播。这是畜群免疫力，它是保护整个人群免受传染病侵害的一种非常有效的方法。

A chart showing how herd immunity works, inthe context of immunisations.

How herd immunity works, in the context ofimmunisations.

Image: The National Institute of Allergyand Infectious Disease (NIAID)

But herd immunity is typically only viewedas a preventive strategy in vaccination programmes. If we don’t have a vaccine– as we don’t for COVID-19 – achieving herd immunity would require asignificant proportion of the population to be infected and recover fromCOVID-19. So what would this mean for the spread of the disease in the UK?

图表展示了在免疫的背景下，群体免疫的工作原理。图片：美国国家过敏和传染病研究所（NIAID）

但是，在疫苗接种计划中，通常只能将群体免疫视为一种预防策略。如果我们没有疫苗（就像我们不使用COVID-19一样），则要获得群体免疫力，就需要大量人口进行感染并从COVID-19中恢复。那么，这对疾病在英国的传播意味着什么呢？

The percentage of the population that needsto be immune to enable herd immunity depends on how transmissible a disease is.This is measured by the term R0, which is how many new infections each casewill generate. For COVID-19, the R0 is estimated to be 3.28, though studies arestill ongoing and this number will probably change. This means that for herdimmunity, about 70% of the UK population would need to be immune to COVID-19.

达到群体免疫需要免疫的人群百分比取决于疾病的传染性，用术语R0来衡量，即每个病例将产生多少新的感染。对于COVID-19，R0估计为3.28，尽管研究仍在进行中，并且该数字可能会改变。这意味着，为了进行群体免疫，大约70％的英国人口需要对COVID-19免疫。

Achieving herd immunity would require well over47 million people to be infected in the UK. Current estimates are that COVID-19has a 2.3% case-fatality rate and a 19% rate of severe disease. This means thatachieving herd immunity to COVID-19 in the UK could result in the deaths ofmore a million people with a further eight million severe infections requiringcritical care.

要获得群体免疫力，英国将需要超过4700万人被感染。目前的估计是，COVID-19的病死率是2.3％，严重疾病的比率是19％。这意味着在英国获得群体对COVID-19的免疫力可能导致超过100万人死亡，另有800万人需要重症监护。

Delay as a public health strategy

However, it is not clear how much of thisdiscussion of herd immunity – reportedly proposed by David Halpern, chiefexecutive of the Behavioural Insights Team, and later blogged about by RobertPeston – is actual government policy.

延迟作为公共卫生策略

但是，目前尚不清楚这种对群体免疫的讨论中，有多少是实际的政府政策？据报道，这是由行为洞察小组首席执行长戴维·哈珀恩（David Halpern）提出，后来又由罗伯特·佩斯顿（RobertPeston）发表的。

Also, the concept as discussed is notsimply to let the disease run its course through the population, but to slowits spread and protect those most vulnerable from severe disease.

同样，所讨论的概念并非只是让疾病在人群中传播，而是减缓疾病的传播并保护最脆弱的人群免受严重疾病的侵害。

Slowing the spread of COVID-19 is apromising strategy, especially when combined with enhanced measures to protectthe elderly and those with underlying health conditions. By slowing the spreadof the disease, the NHS might have more time to prepare, we might be able to developtreatments or vaccines and we will be closer to the summer when we have lowerincidences of other diseases that burden the NHS, such as the flu.

减慢COVID-19的传播是一个有前景的策略，尤其是在与加强措施以保护老年人和具有潜在健康状况的人相结合时。通过放慢疾病的传播速度，NHS可能有更多的准备时间，我们也许能够开发治疗方法或疫苗，并且当我们患其他疾病（例如流感）的几率较低时，我们将接近夏天。

A delay strategy when combined withsurveillance and containment, as recommended by the WHO, could be veryeffective in combating the spread of COVID-19. Yet if we slow the spread of thevirus but are relying on herd immunity to protect the most vulnerable people,we would still need 47 million people to be infected.

按照世界卫生组织的建议，在结合监视和遏制的情况下采取延误策略可能对打击COVID-19的传播非常有效。但是，如果我们减慢病毒的传播速度，但依靠群体免疫来保护最脆弱的人群，我们仍然需要4700万人受到感染。

Even if we manage to protect the most vulnerablepeople (though no discussion is provided on how this will be done or for howlong) the fatality rate for the otherwise healthy portion of the population maystill be 0.5% or higher. This means that even in this unlikely “best case”scenario we would still be looking at more than 236,000 deaths.

即使我们设法保护最弱势的人群（尽管没有讨论如何做到这一点或持续多长时间），否则本来健康的人口的死亡率仍然可能是0.5％或更高。这意味着即使在这种不太可能的“最佳情况”场景中，我们仍将看到超过236,000例死亡。

We can and we must do better than that.China is rapidly controlling the spread of COVID-19 without requiring herdimmunity (only 0.0056% of its population has been infected). Waiting for herdimmunity to COVID-19 to develop in the UK by letting the virus “pass through the community” is not a good public health strategy.

我们可以而且必须做得更好。中国正在迅速控制COVID-19的传播，而无需进行遗传免疫（只有0.0056％的人口被感染）。让病毒“通过社区”传播，等待在英国对COVID-19的免疫性发展，这不是一个好的公共卫生策略。