Up to 45 percent of SARS-CoV-2 infections may be asymptomatic

高达45%的SARS-CoV-2感染病例可能并未出现任何症状

上海译锐翻译       2020-6-16     09:46 a.m.

An extraordinary percentage of people infected by the virus behind the ongoing deadly COVID-19 pandemic never show symptoms of the disease, according to the results of a Scripps Research analysis of public datasets on asymptomatic infections.

根据斯科瑞普斯研究所（Scripps Research）对无症状感染公共数据的分析结果，在目前感染有致命风险的COVID-19传染病病毒的人群中，有很大一部分感染者并未出现任何感染症状。

asymptomatic infection：无症状感染

The findings, published in Annals of Internal Medicine, suggest that asymptomatic infections may account for as much as 45 percent of all COVID-19 cases, playing a significant role in the early and ongoing spread of COVID-19. The report highlights the need for expansive testing and contact tracing to mitigate the pandemic.

研究结果刊登于《内科医学年监》(Annals of Internal Medicine)。根据研究报告，在所有的COVID-19病例中，无症状感染者的比例大概高达45%。如此高的比例在COVID-19早期以及持续传播方面具有重要的推动作用。报告强调，延缓疾病传播需要进行大规模的检测以及接触人群追踪。

"The silent spread of the virus makes it all the more challenging to control," says Eric Topol, MD, founder and director of the Scripps Research Translational Institute and professor of Molecular Medicine at Scripps Research. "Our review really highlights the importance of testing. It's clear that with such a high asymptomatic rate, we need to cast a very wide net, otherwise the virus will continue to evade us."

Eric Topol，医学博士，斯科瑞普斯研究所转化研究所创始人兼所长、斯科瑞普斯分子药物教授表示：“悄无声息地传播使病毒更加难以控制。我们的报告强调了检测的重要性。面对如此高比例的无症状感染，显然我们需要布下天罗地网，否则病毒还会继续和我们玩捉迷藏。”

Together with behavioral scientist Daniel Oran, Topol collected information from testing studies on 16 diverse cohorts from around the world. These datasets -- gathered via keyword searches of PubMed, bioRxiv and medRxiv, as well as Google searches of relevant news reports -- included data on nursing home residents, cruise ship passengers, prison inmates and various other groups.

Topol和行为学家Daniel Oran一道从世界各地16个分散的人群的测试研究中收集信息。这些数据集来自于通过关键词“PubMed、bioRxiv和medRxiv”搜索以及通过Google搜索相关新闻报道，包括养老院人群、邮轮乘客、监狱罪犯以及各种其他群体的数据搜索结果。

cohort：（有共同特点或举止类同的）一群人

"What virtually all of them had in common was that a very large proportion of infected individuals had no symptoms," says Oran. "Among more than 3,000 prison inmates in four states who tested positive for the coronavirus, the figure was astronomical: 96 percent asymptomatic."

Oran表示：“所有人群的一个共同点是很大一部分感染患者没有任何症状。在四个州超过3000名检测结果呈阳性的服刑人员中，无症状的数据比例是非常庞大的：96%的感染者没有任何症状。”

The review further suggests that asymptomatic individuals are able to transmit the virus for an extended period of time, perhaps longer than 14 days. The viral loads are very similar in people with or without symptoms, but it remains unclear whether their infectiousness is of the same magnitude. To resolve that issue, we'll need large-scale studies that include sufficient numbers of asymptomatic people.

报告进一步表明，无症状感染者能够在更长的时间内传播病毒，也许不止14天。有症状感染者或无症状感染者身体中的病毒载量非常相似，但是其感染程度是否具有相同等级则仍不明确。为了解决这一问题，我们需要展开大规模的研究，其中包括足够多的无症状感染者 。

viral load：病毒载量/病毒负荷

The authors also conclude that the absence of symptoms may not imply an absence of harm. CT scans conducted on 54 percent of 76 asymptomatic individuals on the Diamond Princess cruise ship, appear to show significant subclinical lung abnormalities raising the possibility of SARS-CoV-2 infection impacting lung function that might not be immediately apparent. The scientists say further research is needed to confirm the potential significance of this finding.

论文作者总结表示，无症状并不意味着无伤害。在对钻石公主号邮轮上的76名无症状感染中的部分人群（54%）进行CT扫描发现，明显的亚临床肺部异常使SARS-CoV-2感染影响肺功能的可能性增加，而肺功能受影响也许不会立刻显现。科学家们表示，需要进一步研究来证实该结果的潜在影响。

subclinical:无明显临床症候

The authors also acknowledge that the lack of longitudinal data makes distinguishing between asymptomatic and presymptomatic individuals difficult. An asymptomatic individual is someone who is infected with SARS-CoV-2, but never develops symptoms of COVID-19, while a presymptomatic person is similarly infected, but will eventually develop symptoms. Longitudinal testing, which refers to repeated testing of individuals over time, would help differentiate between the two.

作者还承认，缺乏纵向运动数据使得区分无症状和发病前人群困难重重。无症状人群是指感染了SARS-CoV-2，但是不会出现COVID-19症状的人群，而发病前感染者会出现类似的感染情况，但是最终会出现COVID-19的症状。纵向运动数据（即在一段时间内不断对个人进行重复测试），也许对区分两者有所帮助。

"Our estimate of 40 to 45 percent asymptomatic means that, if you're unlucky enough to get infected, the probability is almost a flip of a coin on whether you're going to have symptoms. So to protect others, we think that wearing a mask makes a lot of sense," Oran concludes.

我们对40%-45%无症状感染病例的估计意味着，如果你不幸被感染，那么是否出现感染症状的概率相当于抛掷硬币。对于保护其他人，我们认为戴口罩是非常明智的举措，Oran总结表示。

来源：科学日报     编辑：质控部