Omicron severity: milder but not mild.
Omicron severity: milder but not mild.
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DOI：
10.1016/s0140-6736(22)00056-3
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发表时间：
2022-01-29
期刊：
影响因子：
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通讯作者：
Cowling BJ
中科院分区：
文献类型：
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作者：
Nealon J;Cowling BJ
Nicole Wolter及其同事1在《柳叶刀》中报告了来自南非11000多名COVID-19患者（年龄在19-59岁之间，> 80.0%; 55.9%为女性）的数据，表明感染了受关注的omicron SARS-CoV-2变异体的患者入院几率显著降低（B. 1.1. 529)与同一时期（2021年1 - 0月1日至11月30日;校正比值比[aOR] 0· 2，95% CI 0· 1-0· 3）的其他SARS-CoV-2变异相比，感染omicron变异的患者中严重疾病的几率显著低于感染delta变异的患者（B. 1.617. 2)早期流行波（aOR 0.3，0.2 ~ 0.5）。这些有用的发现-来自与病例，实验室和基因组数据相关的国家级COVID-19医院监测数据-代表了对早期指标的可靠确认，即omicron变体可能导致不太严重的疾病和社会破坏，并且对医院资源的影响比早期流行波中占主导地位的变体小。在确认的SARS-CoV-2感染缺乏广泛的基因分型的情况下，Wolter及其同事1使用TaqPath PCR检测中刺突基因的扩增失败（S基因靶失败[SGTF]）作为omicron变体的替代。SGTF是omicron变体的合理标志物，因为其他循环变体在研究期间不具有该特征。1在omicron变异流行不断扩大的背景下，这些南非数据对其他司法管辖区和时间点的普遍适用性水平具有至关重要的全球重要性。如果这种omicron变异严重疾病风险的降低（与英国观察到的相似）2可能归因于较低的内在毒力，它将向公众和卫生当局提供保证，即最近全球观察到的COVID-19病例数量的惊人激增不会转化为无法控制的住院人数增加，这对疾病控制政策的收紧或放松都有影响。然而，南非出现了反复的感染浪潮，该因素在多大程度上可以解释2021年底SGTF感染影响的减少尚不清楚。平均而言，SARS-CoV-2再感染比初次感染温和，3到2021年12月，超过70%的南非人由于自然感染或疫苗接种而存在抗SARS-CoV-2抗体。4在Wolter及其同事的研究中，1 SGTF感染的患者中既往感染的几率比δ变体感染的患者高出约23倍，这可能是由于omicron变体的免疫逃逸能力可能增加轻度再感染的比例。5鉴于住院前COVID-19检测几乎普遍，而且人口感染率不断增加，一些患者因SARS-CoV-2感染而住院的可能性也可能影响严重程度分析。6为了从群体免疫中分离出内在的严重性，Wolter和同事1通过使用严重性的复合指标（包括入住重症监护室、急性呼吸窘迫、氧气治疗和死亡）比较同期住院的omicron（SGTF）和其他变体（非SGTF）个体来分析疾病的严重性。1该分析是不确定的，可能是由于少数严重的结果;然而，有生物学上的可能性，在一些减少的内在严重程度omicron感染，如实验室研究所示，报告减少的发病机制在动物模型7和较低的复制能力，在人肺细胞中的omicron感染。
In The Lancet, Nicole Wolter and colleagues1 report data from more than 11 000 individuals (> 80· 0% aged 19–59 years; 55· 9% women) with COVID-19 in South Africa indicative of significantly reduced odds of hospital admission for patients infected with the omicron SARS-CoV-2 variant of concern (B. 1.1. 529) versus other SARS-CoV-2 variants during the same period (Oct 1–Nov 30, 2021; adjusted odds ratio [aOR] 0· 2, 95% CI 0· 1–0· 3) and significantly reduced odds of severe disease among patients infected by the omicron variant than among patients infected with the delta variant (B. 1.617. 2) in earlier epidemic waves (aOR 0· 3, 0· 2–0· 5). These useful findings—derived from national-level COVID-19 hospital surveillance data linked with case, laboratory, and genomic data—represent a reassuring confirmation of early indicators that the omicron variant might lead to less severe disease and societal disruption, and have a reduced effect on hospital resources, than variants that dominated earlier pandemic waves. In the absence of widespread genotyping of confirmed SARS-CoV-2 infections, Wolter and colleagues1 used amplification failure of the spike gene (S gene target failure [SGTF]) on the TaqPath PCR assay as a proxy for the omicron variant. SGTF is a reasonable marker for the omicron variant given that other circulating variants did not have this characteristic during the period of study. 1 In the context of expanding omicron variant epidemics, the level of generalisability of these South African data to other jurisdictions and timepoints is of paramount global importance.If this reduction in the risk of severe disease with the omicron variant, similar to that observed in England, 2 could be attributed to lower intrinsic virulence, it would provide reassurance to the public and health authorities that the recent alarming spike in COVID-19 case numbers observed globally would not translate to unmanageable increases in hospitalisations, with implications for the tightening or relaxation of disease control policies. However, South Africa has had repeated waves of infection and the extent to which this factor could explain the reduced effect of SGTF infections in late 2021 is unclear. SARS-CoV-2 reinfections are milder on average than primary infections, 3 and, by December, 2021, more than 70% of South Africans had existing anti-SARS-CoV-2 antibodies as a consequence of either natural infection or vaccination. 4 In the study by Wolter and colleagues, 1 the odds of previous infection were around 23-times higher in SGTF-infected versus delta variant-infected patients, which could be due to the omicron variant’s capacity for immune escape that could increase the proportion of milder reinfections. 5 The possibility of some patients being hospitalised with, rather than for, SARS-CoV-2 infection could also affect severity analyses given near universal, pre-hospitalisation COVID-19 testing and the increasing population prevalence of infection. 6 In an attempt to disentangle intrinsic severity from population immunity, Wolter and colleagues1 analysed disease severity by comparing contemporaneous, hospitalised individuals with the omicron (SGTF) versus other variants (non-SGTF) using a composite measure of severity, which included admission to an intensive care unit, acute respiratory distress, oxygen treatment, and death. 1 This analysis was inconclusive, possibly due to the small number of severe outcomes; however, there is biological plausibility for some reduction in the intrinsic severity of omicron infections, as indicated by laboratory studies that report reduced pathogenesis in an animal model7 and lower replication competence in human lung cells for …