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奥密克戎双亚型正在肆虐美国,其中一种传染性最强

奥密克戎双亚型正在肆虐美国,其中一种传染性最强

Erin Prater 2022-06-30
新病毒大幅降低了疫苗对重症的防护能力。

2022年6月21日,美国总统乔·拜登在华盛顿特区的圣餐教堂新冠病毒疫苗接种诊所里与孩子们打招呼。图片来源:NICHOLAS KAMM / AFP VIA GETTY IMAGES

根据6月28日公布的联邦健康数据,两种能够逃避免疫系统的奥密克戎亚型变异株目前在美国占据主导地位,在短短几周内就超过了所谓的“隐形奥密克戎”和相近的亚型变异株BA.2.12.1。

美国疾病控制和预防中心(U.S. Centers for Disease Control and Prevention)的新数据显示,今年春天,BA.4和BA.5因为其逃避免疫系统的能力而席卷南非,据估计,上周在美国造成了略多于一半(52%)的人感染新冠病毒。

斯克利普斯研究所(Scripps Research)的分子医学教授、斯克里普斯研究转化研究所(Scripps Research Translational Institute)的创始人及所长埃里克·托波尔博士于6月27日在预期病毒会肆虐时写道:“奥密克戎亚型变异株BA.5是我们见过的传染性最强的毒株。”

他说:“它将已经广泛的免疫逃逸提升到新水平,增强了传播能力。”远远超出我们以前所看到的情况。“你可以说,情况没有那么糟糕,因为住院和死亡人数不像我们看到的奥密克戎感染病例那样显著上升,但那只是因为奥密克戎毒株带来了严重影响,而且至少有一些交叉免疫的情况出现。”

BA.2.12.1是另一个在BA.4和BA.5出现之前占据主导地位的奥密克戎亚型变异株,占确诊病例数的42%。所谓的隐形奥密克戎, BA.2,因为其逃避核酸检测的能力而得名,排在第三位,占确诊病例数的近6%。隐形奥密克戎此前一直在美国占据主导地位,直到今年5月BA.2.12.1超过了它,在美国占据主导地位。

目前的疫苗是否能够抵抗BA.5尚无定论。但考虑到从德尔塔毒株到奥密克戎毒株,疫苗对重症的防护能力下降了大约15%,“看到疫苗对住院和死亡病例的防护能力进一步下降,我一点也不惊讶。”托波尔写道。

正如《财富》杂志先前报道的那样,今年3月底,美国首次发现了BA.4和BA.5。在南非发现的这两种变异株于4月和5月迅速席卷南非,尽管当时几乎所有南非人都接种了疫苗或之前感染过新冠病毒。

这两种变异株迅速席卷全球。但托波尔写道,这两种变异株感染病例的上升往往被掩盖,因为在许多国家,这两种变异株感染病例的上升与BA.2感染病例的下降同时发生。这可能会导致出现持续的疫情浪潮,而在现实中,出现的是两波疫情潮——第一波来自较老版本的奥密克戎,第二波来自BA.4/BA.5。

南非最近的一项研究发现,那些之前感染过奥密克戎但没有接种疫苗的人,在感染BA.4和BA.5时,中和抗体下降了近八倍。那些接种过疫苗并在之前感染过奥密克戎的人,中和抗体下降幅度较小,下降了三倍。

今年5月,南非非洲卫生研究所(African Health Research Institute)教授亚历克斯·西加尔告诉《财富》杂志,感染新亚型变异株的症状与感染奥密克戎毒株的典型症状类似,包括发烧、嗅觉丧失和身体不适。

他说:“我没有看到呼吸困难的早期症状,这是让这种疾病如此危险的新冠肺炎主要特异性症状。虽然感染后身体感觉不适,但死亡的几率更小了。”(财富中文网)

译者:中慧言-王芳

根据6月28日公布的联邦健康数据,两种能够逃避免疫系统的奥密克戎亚型变异株目前在美国占据主导地位,在短短几周内就超过了所谓的“隐形奥密克戎”和相近的亚型变异株BA.2.12.1。

美国疾病控制和预防中心(U.S. Centers for Disease Control and Prevention)的新数据显示,今年春天,BA.4和BA.5因为其逃避免疫系统的能力而席卷南非,据估计,上周在美国造成了略多于一半(52%)的人感染新冠病毒。

斯克利普斯研究所(Scripps Research)的分子医学教授、斯克里普斯研究转化研究所(Scripps Research Translational Institute)的创始人及所长埃里克·托波尔博士于6月27日在预期病毒会肆虐时写道:“奥密克戎亚型变异株BA.5是我们见过的传染性最强的毒株。”

他说:“它将已经广泛的免疫逃逸提升到新水平,增强了传播能力。”远远超出我们以前所看到的情况。“你可以说,情况没有那么糟糕,因为住院和死亡人数不像我们看到的奥密克戎感染病例那样显著上升,但那只是因为奥密克戎毒株带来了严重影响,而且至少有一些交叉免疫的情况出现。”

BA.2.12.1是另一个在BA.4和BA.5出现之前占据主导地位的奥密克戎亚型变异株,占确诊病例数的42%。所谓的隐形奥密克戎, BA.2,因为其逃避核酸检测的能力而得名,排在第三位,占确诊病例数的近6%。隐形奥密克戎此前一直在美国占据主导地位,直到今年5月BA.2.12.1超过了它,在美国占据主导地位。

目前的疫苗是否能够抵抗BA.5尚无定论。但考虑到从德尔塔毒株到奥密克戎毒株,疫苗对重症的防护能力下降了大约15%,“看到疫苗对住院和死亡病例的防护能力进一步下降,我一点也不惊讶。”托波尔写道。

正如《财富》杂志先前报道的那样,今年3月底,美国首次发现了BA.4和BA.5。在南非发现的这两种变异株于4月和5月迅速席卷南非,尽管当时几乎所有南非人都接种了疫苗或之前感染过新冠病毒。

这两种变异株迅速席卷全球。但托波尔写道,这两种变异株感染病例的上升往往被掩盖,因为在许多国家,这两种变异株感染病例的上升与BA.2感染病例的下降同时发生。这可能会导致出现持续的疫情浪潮,而在现实中,出现的是两波疫情潮——第一波来自较老版本的奥密克戎,第二波来自BA.4/BA.5。

南非最近的一项研究发现,那些之前感染过奥密克戎但没有接种疫苗的人,在感染BA.4和BA.5时,中和抗体下降了近八倍。那些接种过疫苗并在之前感染过奥密克戎的人,中和抗体下降幅度较小,下降了三倍。

今年5月,南非非洲卫生研究所(African Health Research Institute)教授亚历克斯·西加尔告诉《财富》杂志,感染新亚型变异株的症状与感染奥密克戎毒株的典型症状类似,包括发烧、嗅觉丧失和身体不适。

他说:“我没有看到呼吸困难的早期症状,这是让这种疾病如此危险的新冠肺炎主要特异性症状。虽然感染后身体感觉不适,但死亡的几率更小了。”(财富中文网)

译者:中慧言-王芳

A pair of immune-evading Omicron subvariants are now dominant in the U.S., having overtaken so-called "stealth Omicron" and close relative BA.2.12.1 in mere weeks, according to federal health data released on June 28.

BA.4 and BA.5, which swept South Africa this spring along thanks to their ability to evade immunity, were estimated to have caused slightly more than half (52%) of COVID infections in the U.S. last week, according to new data from the U.S. Centers for Disease Control and Prevention.

“The Omicron subvariant BA.5 is the worst version of the virus that we’ve seen,” Dr. Eric Topol, a professor of molecular medicine at Scripps Research and founder and director of the Scripps Research Translational Institute, wrote on June 27 in anticipation of the viral coup.

"It takes immune escape, already extensive, to the next level, and, as a function of that, enhanced transmissibility," well beyond what has been seen before, he wrote. "You could say it’s not so bad because there hasn’t been a marked rise in hospitalizations and deaths as we saw with Omicron, but that’s only because we had such a striking adverse impact from Omicron, for which there is at least some cross-immunity."

BA.2.12.1, another Omicron subvariant dominant before the advent of BA.4 and BA.5, was responsible for 42% of cases. So-called stealth Omicron, BA.2, nicknamed for its ability to evade detection on PCR tests, came in third, comprising nearly 6% of cases. It had been dominant in the U.S. until BA.2.12.1 overtook it in May.

The jury is still out on whether current vaccines hold up against BA.5. But given that vaccines experienced an approximate 15% drop in protection against severe disease from Delta to Omicron, "it would not be at all surprising to me to see further decline of protection against hospitalizations and deaths," Topol wrote.

BA.4 and BA.5 were first detected in the U.S. in late March, as Fortune previously reported. The variants, discovered in South Africa, quickly took hold in the country in April and May despite the fact that almost all South Africans had been vaccinated or previously had COVID by that point.

The pair of variants are quickly taking hold globally. But their rise is often masked because in many countries, it's occurring at the same time as a decline in BA.2 infections, Topol wrote. This can lead to the appearance of a sustained wave when, in reality, dual waves are present—the first from an older version of Omicron, and the second from BA.4/BA.5.

A recent study out of South Africa found that those who had been previously infected with Omicron but not vaccinated experienced a nearly eightfold drop in neutralizing antibodies when exposed to BA.4 and BA.5. Those who had been vaccinated and previously infected with Omicron saw a milder threefold decrease.

Alex Sigal, a professor at the Africa Health Research Institute in South Africa, told Fortune in May that symptoms of the new subvariants are similar to typical Omicron symptoms, which include fever, loss of smell, and malaise.

“I haven’t seen early symptoms of respiratory distress, the major COVID-specific symptom that makes this disease so dangerous,” he said. “It doesn’t feel nice, but there’s less chance of dying.”

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