Blood group O is associated with a decreased risk for contracting SARS-CoV-2 infection, research published in Blood Advances showed.
Identification of risk factors for contracting and developing serious illness following infection with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is of paramount interest.
The study performed a retrospective cohort analysis of all Danish individuals tested for SARS-CoV-2 between 27 February 2020 and 30 July 2020, with a known ABO and RhD blood group, to determine the influence of common blood groups on virus susceptibility.
Distribution of blood groups was compared with data from non-tested individuals. Participants (29% of whom were male) included 473654 individuals tested for SARS-CoV-2 using real-time polymerase chain reaction (7422 positive and 466232 negative) and 2204742 nontested individuals, accounting for 38% of the total Danish population.
Hospitalisation and death from Covid-19, age, cardiovascular co-morbidities, and job status were also collected for confirmed infected cases.
Severe acute respiratory syndrome-coronavirus 2 (SARS-CoV-2) has spread rapidly since its emergence in December 2019, causing a pandemic with 18093891 people infected globally (as of 3 August 2020).
In severe cases, individuals develop a number of symptoms, including acute respiratory illness, collectively known as coronavirus disease 2019 (Covid-19).
Development of Covid-19 is associated with age, sex, and co-morbidities, such as cardiovascular diseases, although severe disease is not limited to these risk groups.
Recent reports have suggested that ABO blood groups might play a role in the infection, with a lower than expected prevalence of blood group O individuals among patients.
Blood group A and B glycosyltransferases also affect glycosylation in a large number of cell types, including epithelial cells in the respiratory tract and shed viral particles.
A, B, and AB individuals are also at increased risk for thrombosis and cardiovascular diseases, which are important comorbidities among hospitalised Covid-19 patients, possibly mediated by glycosylation of proteins involved in haemostasis.
To obtain valid estimates of relative risk (RR), representativeness of the reference material is important. Although blood group frequencies and susceptibility for SARS-CoV-2 can vary substantially among ethnic groups, Denmark is a relatively ethnically homogenous society with free access to health care services.
There was a slight, but statistically significant, difference in blood group distribution between the SARS-CoV-2- individuals and the reference population.
Among the SARS-CoV-2 individuals, considerably fewer group O individuals were found, conversely, more A, B, and AB individuals were noted.
When blood group O was excluded, no significant difference was seen among A, B, and AB.
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