Abstract：
ABO blood group is long known to be an influencing factor for the susceptibility to infectious diseases, and many studies have been describing associations between ABO blood types and COVID-19 infection and severity, with conflicting findings. This narrative review aims to summarize the literature regarding associations between the ABO blood group and COVID-19. Blood type O is mostly associated with lower rates of SARS-CoV-2 infection, while blood type A is frequently described as a risk factor. Although results regarding the risk of severe outcomes are more variable, blood type A is the most associated with COVID-19 severity and mortality, while many studies describe O blood type as a protective factor for the disease progression. Furthermore, genetic associations with both the risk of infection and disease severity have been reported for the ABO locus. Some underlying mechanisms have been hypothesized to explain the reported associations, with incipient experimental data. Three major hypotheses emerge: SARS-CoV-2 could carry ABO(H)-like structures in its envelope glycoproteins and would be asymmetrically transmitted due to a protective effect of the ABO antibodies, ABH antigens could facilitate SARS-CoV-2 interaction with the host\' cells, and the association of non-O blood types with higher risks of thromboembolic events could confer COVID-19 patients with blood type O a lower risk of severe outcomes. The hypothesized mechanisms would affect distinct aspects of the COVID-19 natural history, with distinct potential implications to the disease transmission and its management.
摘要：
长期以来，人们都知道ABO血型是感染性疾病易感性的影响因素，许多研究已经描述了ABO血型与COVID-19感染和严重程度之间的关系，矛盾的发现。这篇叙述性综述旨在总结有关ABO血型与COVID-19之间关联的文献。O型血主要与SARS-CoV-2感染率较低有关，而A型血经常被描述为危险因素。尽管关于严重结局风险的结果差异更大，A型血与COVID-19严重程度和死亡率最相关，而许多研究将O型血描述为疾病进展的保护因素。此外，已经报道了ABO基因座与感染风险和疾病严重程度的遗传关联.已经假设了一些潜在的机制来解释所报告的关联，初步的实验数据。出现了三个主要假设：SARS-CoV-2可能在其包膜糖蛋白中携带ABO（H）样结构，并且由于ABO抗体的保护作用而不对称传播，ABH抗原可以促进SARS-CoV-2与宿主细胞的相互作用，非O型血型与较高血栓栓塞事件风险的关联可使O型血COVID-19患者出现严重结局的风险较低.假设的机制将影响COVID-19自然史的不同方面，对疾病传播及其管理有明显的潜在影响。
