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关于“隐形奥密克戎”,我们需要知道这些

关于“隐形奥密克戎”,我们需要知道这些

Andrew Marquardt 2022-01-28
BA.2变异毒株在美国的确诊病例数仍然很低,但卫生专家已经开始加强监测。

美国还没送走奥密克戎,又碰上了新变异毒株。

BA.2变异又称“隐形奥密克戎”,在美国的确诊病例数仍然很低,但卫生专家已经开始加强监测。据华盛顿的媒体KOMO News报道,到目前为止,美国的BA.2感染病例不到100例,华盛顿州和得克萨斯州等地已经确认出现这种变异毒株。

近几周在欧洲和亚洲部分地区,该新型变异毒株导致的确诊病例逐渐增加。在丹麦,每天新增新冠确诊病例总数约为40000例,其中“隐形奥密克戎”感染病例约占65%。截至1月21日,英国已经确诊426例BA.2感染病例。上周,英国卫生当局已经将BA.2列为“正在调查的变种”。

“隐形奥密克戎”在欧洲扩散的迹象预示着,这种新变异毒株今后在美国的新增病例中可能将占据更大的比例。因此,我们有必要更深入了解“隐形奥密克戎”。

新变异毒株与奥密克戎有何不同?

根据英国卫生安全局(U.K. Health Security Agency)的说法,与主流的奥密克戎BA.1毒株(“原始”奥密克戎)相比, BA.2亚型毒株——“隐形奥密克戎”缺少了一种突变,而这种突变正是PCR检测识别奥密克戎的关键。

BA.1在“S”刺突基因中缺失了一个基因,原本医生能够依靠该特征通过PCR检测快速识别病毒。根据英国卫生安全局的数据,BA.2不包含该段基因缺失,因此PCR检测中很难将新变异阳性病例判定为奥密克戎感染。

但一些专家表示,这并不意味着常规新冠检测验不出新的亚型毒株,只是说PCR检测呈阳性时,判断是否属于奥密克戎感染有难度。

瑞士巴塞尔大学(University of Basel)的计算生物学家科尼利厄斯·罗默在推特(Twitter)上写道:“BA.2可以通过PCR检测到,只是可能看起来不是BA.1(另一种奥密克戎变异)。感染BA.2的人检测结果仍然会显示阳性。现在却有谣传称BA.2无法检测,挺令人失望。”

目前尚不清楚BA.2的突变危害有多大,以及对传染性有何影响,但研究人员注意到,新变异与BA.1(原始奥密克戎)相比可能有超过28个突变。因此,一些人呼吁将该变异毒株单独认定为新类型,并用希腊语字母命名。

无需过度担心?

丹麦已经检测到大量“隐形奥密克戎”病例,早期报告显示,与原始奥密克戎相比,新变异病例住院率不会增加。

上周,丹麦的国家传染病研究中心国立血清研究所(Statens Serum Institut)在一份声明中称:“初步分析显示,BA.2与BA.1导致的住院率没有差异,估计新冠疫苗对预防BA.2重症也有效果。"

但一些专家仍然表示,新变异引起了一些担忧。虽然相关研究并未明确表明新变异的传染性比奥密克戎更强(奥密克戎本身传染性就比之前的新冠病毒厉害),但欧洲和亚洲的病例不断增加还是引起了专家的警惕。

伦敦帝国理工学院(Imperial College of London)的病毒学家汤姆·皮科克于1月26日在推特上写道:“BA.2在多个国家持续蔓延,某种程度上可能说明其传染性比BA.1更强。”

皮科克没有立即回复《财富》杂志置评的请求。

下一步应该怎么做?

1月24日,世界卫生组织(World Health Organization)建议官员采取额外措施,以确定与原始奥密克戎相比,BA.2是否会带来新的挑战。

世界卫生组织写道:“研究BA.2的免疫逃逸特性和毒性等特征,应该优先于BA.1 (相对而言)。”

至于美国的BA.2与原始奥密克戎传染情况具体有何区别,只有时间能够给出答案。

目前,BA.2的病例数仍然远低于BA.1,美国疾病控制与预防中心(Centers for Disease Control and Prevention)表示,将持续监测该变异在国内外传播情况。

“尽管最近BA.2谱系在一些国家的病例中比例有所增加,但在美国以及全球流行病毒中的比例仍然很低。目前还没有足够的数据判定BA.2谱系是否比BA.1谱系传染性更强,或者适应能力更强。”美国疾病控制与预防中心的发言人克里斯汀·诺德伦德在给《华盛顿邮报》(The Washington Post)的一份声明中说。(188金宝搏 下载)

译者:梁宇

审校:夏林

美国还没送走奥密克戎,又碰上了新变异毒株。

BA.2变异又称“隐形奥密克戎”,在美国的确诊病例数仍然很低,但卫生专家已经开始加强监测。据华盛顿的媒体KOMO News报道,到目前为止,美国的BA.2感染病例不到100例,华盛顿州和得克萨斯州等地已经确认出现这种变异毒株。

近几周在欧洲和亚洲部分地区,该新型变异毒株导致的确诊病例逐渐增加。在丹麦,每天新增新冠确诊病例总数约为40000例,其中“隐形奥密克戎”感染病例约占65%。截至1月21日,英国已经确诊426例BA.2感染病例。上周,英国卫生当局已经将BA.2列为“正在调查的变种”。

“隐形奥密克戎”在欧洲扩散的迹象预示着,这种新变异毒株今后在美国的新增病例中可能将占据更大的比例。因此,我们有必要更深入了解“隐形奥密克戎”。

新变异毒株与奥密克戎有何不同?

根据英国卫生安全局(U.K. Health Security Agency)的说法,与主流的奥密克戎BA.1毒株(“原始”奥密克戎)相比, BA.2亚型毒株——“隐形奥密克戎”缺少了一种突变,而这种突变正是PCR检测识别奥密克戎的关键。

BA.1在“S”刺突基因中缺失了一个基因,原本医生能够依靠该特征通过PCR检测快速识别病毒。根据英国卫生安全局的数据,BA.2不包含该段基因缺失,因此PCR检测中很难将新变异阳性病例判定为奥密克戎感染。

但一些专家表示,这并不意味着常规新冠检测验不出新的亚型毒株,只是说PCR检测呈阳性时,判断是否属于奥密克戎感染有难度。

瑞士巴塞尔大学(University of Basel)的计算生物学家科尼利厄斯·罗默在推特(Twitter)上写道:“BA.2可以通过PCR检测到,只是可能看起来不是BA.1(另一种奥密克戎变异)。感染BA.2的人检测结果仍然会显示阳性。现在却有谣传称BA.2无法检测,挺令人失望。”

目前尚不清楚BA.2的突变危害有多大,以及对传染性有何影响,但研究人员注意到,新变异与BA.1(原始奥密克戎)相比可能有超过28个突变。因此,一些人呼吁将该变异毒株单独认定为新类型,并用希腊语字母命名。

无需过度担心?

丹麦已经检测到大量“隐形奥密克戎”病例,早期报告显示,与原始奥密克戎相比,新变异病例住院率不会增加。

上周,丹麦的国家传染病研究中心国立血清研究所(Statens Serum Institut)在一份声明中称:“初步分析显示,BA.2与BA.1导致的住院率没有差异,估计新冠疫苗对预防BA.2重症也有效果。"

但一些专家仍然表示,新变异引起了一些担忧。虽然相关研究并未明确表明新变异的传染性比奥密克戎更强(奥密克戎本身传染性就比之前的新冠病毒厉害),但欧洲和亚洲的病例不断增加还是引起了专家的警惕。

伦敦帝国理工学院(Imperial College of London)的病毒学家汤姆·皮科克于1月26日在推特上写道:“BA.2在多个国家持续蔓延,某种程度上可能说明其传染性比BA.1更强。”

皮科克没有立即回复《财富》杂志置评的请求。

下一步应该怎么做?

1月24日,世界卫生组织(World Health Organization)建议官员采取额外措施,以确定与原始奥密克戎相比,BA.2是否会带来新的挑战。

世界卫生组织写道:“研究BA.2的免疫逃逸特性和毒性等特征,应该优先于BA.1 (相对而言)。”

至于美国的BA.2与原始奥密克戎传染情况具体有何区别,只有时间能够给出答案。

目前,BA.2的病例数仍然远低于BA.1,美国疾病控制与预防中心(Centers for Disease Control and Prevention)表示,将持续监测该变异在国内外传播情况。

“尽管最近BA.2谱系在一些国家的病例中比例有所增加,但在美国以及全球流行病毒中的比例仍然很低。目前还没有足够的数据判定BA.2谱系是否比BA.1谱系传染性更强,或者适应能力更强。”美国疾病控制与预防中心的发言人克里斯汀·诺德伦德在给《华盛顿邮报》(The Washington Post)的一份声明中说。(188金宝搏 下载)

译者:梁宇

审校:夏林

A new coronavirus variant has hit the U.S.

Case numbers of the so-called “stealth Omicron” variant remain low, but health experts are monitoring the emergence of a new strain in the country. So far, there are fewer than 100 confirmed cases of what scientists have named the BA.2 sub-variant in the U.S., according to reporting from Washington’s KOMO News. The strain has been positively identified in Washington and Texas, among others.

But in Europe and parts of Asia, the new variant has accounted for a growing number of cases in recent weeks. In Denmark—where daily COVID case totals are around 40,000—"stealth Omicron" has now been identified in around 65% of new infections. In the U.K., there were 426 confirmed cases of the new variant as of Jan. 21, prompting health authorities to classify BA.2 as “variant under investigation” last week.

If Europe is any indication, “stealth Omicron” could begin accounting for a larger percentage of cases in the U.S. So let’s take a deeper look at everything we know so far about “stealth Omicron,” the new coronavirus variant to arrive in the U.S.

How is it different from Omicron?

“Stealth Omicron,” or the the BA.2 sub-strain of coronavirus differs from the more dominant BA.1 Omicron strain (what we think of as “original” Omicron) because it lacks a mutation that made the initial strain possible to detect as Omicron in PCR tests, according to the U.K. Health Security Agency.

BA.1 contains a genetic deletion in the “S” spike gene, and allows for doctors to quickly identify and classify positive PCR tests as Omicron. BA.2 does not contain that genetic deletion, so it is harder to classify positive cases of the new variant as Omicron in PCR tests, according to the U.K. Health Security Agency.

But some experts say this does not mean the new sub-strain evades general detection in COVID tests. It just means it is harder to classify as Omicron when it appears in positive PCR tests.

“BA.2 is detectable by PCR…Depending on the PCR test used it may not look like BA.1 (the other Omicron). But it will still give a positive result," Cornelius Roemer, a computational biologist at Switzerland's University of Basel, wrote on Twitter. “[It's] frustrating to see falsehood about non-detectability still around."

It’s still unclear how much BA.2’s mutations impact it’s severity or transmissibility, but researchers have noted that the new variant may have upwards of 28 different mutations from BA.1, the original Omicron. As a result, some are calling for the new variant to be classified as its own variant, with its own Greek letter.

How worried should we be?

Early reports out of Denmark, where a large number of cases of stealth Omicron have been detected, suggest that the new variant does not cause an increase in hospitalization rates when compared to the original Omicron.

“Initial analysis shows no differences in hospitalizations for BA.2 compared to BA.1,” Denmark’s Statens Serum Institut, a government-run infectious disease research center, said in a statement last week. “It is expected that vaccines also have an effect against severe illness upon BA.2 infection.”

But some experts still say the new variant presents some cause for concern. Research does not clearly show that the new variant is more transmissible than Omicron—which itself is more transmissible than previous coronavirus variants—but the rising case numbers in Europe and Asia have experts on alert.

"[Consistent] growth across multiple countries is evidence BA.2 may be some degree more transmissible than BA.1," Tom Peacock, a virologist from the Imperial College of London, tweeted on January 26.

Peacock did not immediately return Fortune’s request for further comment.

What's next?

On January 24, the World Health Organization recommended officials take additional measures to determine whether BA.2 poses new challenges compared to the original Omicron.

“Investigations into the characteristics of BA. 2, including immune escape properties and virulence, should be prioritized independently (and comparatively) to BA. 1,” the WHO wrote.

Only time will tell how BA.2 stacks up against the original Omicron in the U.S.

Case numbers are still far below the BA.1 Omicron strain, and the Centers for Disease Control and Prevention says it will continue to monitor the variant as it circulates in the U.S. and abroad.

“Although the BA.2 lineage has recently increased in proportion in some countries, it remains a very low proportion of circulating viruses in the United States and globally. Currently, there are insufficient data to determine whether the BA.2 lineage is more transmissible or has a fitness advantage over the BA.1 lineage,” said Kristen Nordlund, a CDC spokesperson, in a statement to The Washington Post.

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