【齐心抗疫】新型冠状病毒致死率低于非典，但传染性更强

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The coronavirus is less deadly than SARS — but that may explain why it's more contagious
新型冠状病毒致死率低于非典——也许正因如此其传染性才更强


An effective virus can spread by not being too virulent like influenza and/or sustaining a long incubation period like HIV.
高传染性的病毒可以通过降低自身致命性（比如流感病毒），以及/或者维持较长的潜伏期（比如艾滋病病毒）来扩大传播范围。

The coronavirus is now responsible for 304 deaths in China. It has a lower fatality rate than SARS, but that also makes it potentially more likely to spread.
目前，新型冠状病毒在中国已造成304人死亡。虽然该病毒致死率低于非典，但这也使得它进一步扩散的可能性增大。

Two months into the epidemic, the coronavirus has not proven to be as deadly as the SARS virus. That, however, may also help explain why it's spreading so quickly. It has an incubation period of up to two weeks, which enables the virus to spread through person-to-person contact.
自疫情爆发的两个月以来，已有研究证明新型冠状病毒并不会像非典一样致命。然而也许正因如此，这恰好解释了为何这种病毒的传播速度能够如此之快。该病毒的潜伏期长达两周，这也使得它有机会通过人与人之间的接触来传播。

The coronavirus, a highly contagious, pneumonia-causing illness that infects the respiratory tract, was responsible for 304 deaths in China, with 45 new deaths reported in the previous 24-hour period, and 14,380 infections worldwide, according to the latest figures released by China's National Health Commission on Sunday (Saturday EST).
新型冠状病毒传染性极强，能够引发肺炎从而导致呼吸道感染。根据中国国家卫生委员会周日（美国东部时间周六）发布的最新数据，该病毒在中国已造成304人死亡（截至发稿前24小时，又新增45例死亡病例），全球范围内共14380人感染。

SARS, or severe acute respiratory syndrome, infected 8,096 people worldwide with approximately 774 official SARS-related deaths; most of those infections occurred during a nine-month period from 2002 to 2003. Even with 43 new fatalities reported over 24 hours, the fatality rate remains steady.
非典，又称重症急性呼吸综合症，全球范围内共8096人感染，官方累计死亡病例约774人，绝大多数的患者是在2002至2003年内的九个月之间被确诊的。尽管当时24小时内新增了43例死亡病例，非典的致死率依然保持稳定。

SARS had a fatality rate of 9.6% compared to the fatality rate of 2.1% for this new 2019-nCoV strain of coronavirus, which has remained steady for the last several weeks. However, that death toll could rise as the weeks progress, and drug companies scramble to come up with a vaccine for the virus. Whether the fatality rate remains steady has yet to be determined.
较之非典9.6%的致死率，新型冠状病毒的致死率在过去几周内一直维持在2.1%。然而，死亡人数很有可能随着时间的推移而持续上升，医药公司也正在努力研发针对该病毒的疫苗。其致死率能否保持稳定，目前尚无定论。

Assuming an incubation period of up to 14 days, with an average of 7 days, before a person presents with symptoms of the virus and succumbs to the illness within the first week of diagnosis, the current fatality rate may yet underestimate the eventual rate. The current fatality rate of 259 based on the total number of cases reported four days ago (4,600) equates to a fatality rate of closer to 5.6%.
假设该病毒的潜伏期最长可达14天（平均7天），在患者出现任何症状以前或是在确诊的第一周后就去世之前，当前的致死率可能会高于真正的结果。根据4天前的案例报告可知，在4600例确诊的患者当中死亡人数共259人，因此目前该病毒的致死率在5.6%左右。

If, on the other hand, the number of infections is as vastly underestimated, even more so than the fatality rate, that 2.1% coronavirus fatality rate could fall, which would be good news for those who have contracted the illness. (The World Health Organization has declared a global health emergency.)
另一方面，哪怕新型冠状病毒的致死率存在被低估的现象，但如果感染人数同样被大幅度低估，那么实际的致死率则可能低于2.1%。这对已经感染的患者而言并非坏消息。（目前，世界卫生组织已宣布进入全球卫生紧急状态。）

Maciej Boni, an associate professor of biology, at Pennsylvania State University, said the 2009 H1N1 flu pandemic initially overestimated the final fatality rate, while the SARS fatality rate rose as the virus spread.
宾夕法尼亚州立大学的生物学副教授马切伊·博尼（Maciej Boni）表示，人们一开始其实是高估了2009年甲型H1N1流感的最终致死率，虽然非典的实际致死率的确是随着病毒的扩散而上升。

Boni wrote on the online science magazine LiveScience, “During the 2009 influenza pandemic, the earliest reports listed 59 deaths from approximately 850 suspected cases, which suggested an extremely high case fatality of 7%. However, the initially reported information of 850 cases was a gross underestimate. This was simply due to a much larger number of mild cases that did not report to any health system and were not counted.”
博尼在在线科学杂志《LiveScience》中写道：“2009年流感爆发期间，最早的报告中显示共59人死亡，约850例疑似感染病例，这意味着这场流感的致死率高达7%。然而事实上，疑似感染的病例远不止初期报告中的850例这么点，这单纯是因为有很多症状较轻的患者根本没有上报任何卫生系统，他们因此也就未被归为疑似病例。”

“After several months — when pandemic data had been collected from many countries experiencing an epidemic wave — the 2009 influenza turned out to be much milder than was thought in the initial weeks. Its case fatality was lower than 0.1% and in line with other known human influenza viruses,” he added.
他还补充道：“几个月后——就在拿到了许多经历了那次流感的国家的流行病学数据之后，事实证明，2009年的那场流感实际上要比最初预期的温和得多。和其他人类已知的流感病毒一样，该病确诊案例的死亡率远低于0.1%。”

But even that fatality rate is smaller than the SARS fatality rate. The difference in these two fatality rates gives more context as to why the coronavirus has spread so quickly. Medical experts say an effective flu-like virus can extend its reach by not killing its host too rapidly and/or making the host sick enough to pass it on before finally becoming bedridden.
然而，即使新型冠状病毒的致死率要低于非典，两者在致死率上的差异仍旧能够为新型冠状病毒为何能够传播地如此之快而提供更多线索。医学专家表示，高传染性的流感类病毒可以通过缓慢地杀死它的宿主，以及/或者使其宿主出现传染性症状来扩大传染范围。

“Every now and then a disease becomes so dangerous that it kills the host,” Matan Shelomi, an entomologist and assistant professor at National Taiwan University, wrote on Quora in 2017. But, ideally for the host at least, it must strike a balance.
2017年国立台湾大学昆虫学家兼助理教授马坦·谢洛米（Matan Shelomi）在美版知乎（Quora）上写道：“一种疾病常常会变得十分致命以至于杀死它的宿主。”但是，在理想状态下它一定会谋求某种平衡，至少不会轻易杀死宿主。

“If the disease is able to spread to another host before the first host dies, then it is not too lethal to exist. Evolution cannot make it less lethal so long as it can still spread,” he added. “If a hypothetical disease eradicates its only host, both will indeed go extinct.”
“如果这种疾病能够在第一个宿主死亡前传播到另一个宿主身上，那么它的致命性将会一直存在。只要它还可以继续传播，在进化的过程中它的致命性就不会减弱。”马坦补充道，“假设有种病毒杀死了它唯一的宿主，那么这种病毒和它的宿主都将走向灭亡。”

That, he said, is why the Black Death, which ravaged much of Europe and Asia in the Middle Ages is now extinct. “The strain of the Black Death plague (Yersinia pestis) from the 14th Century was too virulent and is now extinct,” with only modern, less devastating strains in existence.
他还表示，这也正是黑死病能够在中世纪席卷欧亚大陆上的许多国家而如今却已经绝迹的原因。“14世纪的黑死病毒株（鼠疫杆菌）毒性太强，而现在它们却已经灭绝了。”现在只有那些破坏性较小的毒株存活了下来。

So will the latest coronavirus outbreak be more similar to the 2002-2003 SARS outbreak or the 2009 H1N1 influence pandemic? Boni wrote on LiveScience: “I am a professor of biology who studies the evolution and epidemiology of infectious disease, and in my view, in late January 2020, we do not yet have enough solid evidence to answer this question.”
那么，最近爆发的这场由新型冠状病毒引起的疫情会像2002至2003年爆发的非典，或是2009年爆发的甲型H1N1流感一样吗？博尼曾在《LiveScience》中写道：“我是一名研究传染病演变和流行病学的生物学教授，在我看来，截至2020年1月底，我们暂无确切的证据来回答这一问题。”

By Quentin Fottrell
Published: MarketWatch.com, Feb 1, 2020 10:38 pm ET

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