Blood group type A secretors are associated with a higher risk of COVID-19 cardiovascular disease complications

Investigating ABO Blood Groups and Secretor Status in Relation to SARS-CoV-2 Infection and COVID-19 Severity

The ABO blood groups, Lewis antigens, and secretor systems are important components of transfusion medicine. These interconnected systems have been also shown to be associated with differing susceptibility to bacterial and viral infections, likely as the result of selection over the course of evolution and the constant tug of war between humans and infectious microbes. This comprehensive narrative review aimed to explore the literature and to present the current state of knowledge on reported associations of the ABO, Lewis, and secretor blood groups with SARS-CoV-2 infection and COVID-19 severity. Our main finding was that the A blood group may be associated with increased susceptibility to SARS-CoV-2 infection, and possibly also with increased disease severity and overall mortality. The proposed pathophysiological pathways explaining this potential association include antibody-mediated mechanisms and increased thrombotic risk amongst blood group A individuals, in addition to altered inflammatory cytokine expression profiles. Preliminary evidence does not support the association between ABO blood groups and COVID-19 vaccine response, or the risk of developing long COVID. Even though the emergency state of the pandemic is over, further research is needed especially in this area since tens of millions of people worldwide suffer from lingering COVID-19 symptoms.

Association of ABO and Rhesus blood groups with severe outcomes from non-SARS-CoV-2 respiratory infection: A prospective observational cohort study in Bristol, UK 2020-2022

Despite significant global morbidity associated with respiratory infection, there is a paucity of data examining the association between severity of non-SARS-CoV-2 respiratory infection and blood group. We analysed a prospective cohort of adults hospitalised in Bristol, UK, from 1 August 2020 to 31 July 2022, including patients with acute respiratory infection (pneumonia [n = 1934] and non-pneumonic lower respiratory tract infection [NP-LRTI] [n = 1184]), a negative SARS-CoV-2 test and known blood group status. The likelihood of cardiovascular complication, survival and hospital admission length was assessed using regression models with group O and RhD-negative status as reference groups. Group A and RhD-positive were over-represented in both pneumonia and NP-LRTI compared to a first-time donor population (p < 0.05 in all); contrastingly, group O was under-represented. ABO group did not influence cardiovascular complication risk; however, RhD-positive patients with pneumonia had a reduced odds ratio (OR) for cardiovascular complications (OR = 0.77 [95% CI = 0.59-0.98]). Compared to group O, group A individuals with NP-LRTI were more likely to be discharged within 60 days (hazard ratio [HR] = 1.17 [95% CI = 1.03-1.33]), while group B with pneumonia was less likely (HR = 0.8 [95% CI = 0.66-0.96]). This analysis provides some evidence that blood group status may influence clinical outcome following respiratory infection, with group A having increased risk of hospitalisation and RhD-positive patients having reduced cardiovascular complications.

Cardiovascular Diseases Risk Predictors: ABO Blood Groups in a Different Role

Cardiovascular diseases (CVDs) pose a serious threat to people's health, with extremely high global morbidity, mortality, and disability rates. This study aimed to review the literature that examined the relationship between blood groups and CVD. Many studies have reported that non-O blood groups are associated with an increased risk and severity of coronary artery disease and acute coronary syndromes. Non-O blood groups increase the risk and severity of these conditions by increasing von Willebrand factor and plasma cholesterol levels and inducing endothelial dysfunction and inflammation. They have also been linked with increased coronary artery calcification, coronary lesion complexity, and poor collateral circulation. Blood groups also affect the prognosis of coronary artery disease and acute coronary syndrome and can alter the rate of complications and mortality. Several cardiovascular complications have been described for coronavirus disease 2019, and blood groups can influence their occurrence. No studies have found a significant relationship between the Lewis blood group and CVD. In conclusion, people with non-O blood groups should be vigilantly monitored for cardiovascular risk factors as prevention and proper treatment of these risk factors may mitigate their risk of CVD and adverse cardiovascular events.

Evaluation and Mechanistic Investigation of Human Milk Oligosaccharide against SARS-CoV-2

Four human milk oligosaccharides (HMOs), 3'-sialyllactose (3'-SL), 6'-sialyllactose (6'-SL), 2'-fucosyllactose (2'-FL), and 3-fucosyllactose (3-FL), were assessed for their possible antiviral activity against the SARS-CoV-2 spike receptor binding domain (RBD) in vitro. Among them, only 2'-FL/3-FL exhibited obvious antibinding activity against direct binding and trans-binding in competitive immunocytochemistry and enzyme-linked immunosorbent assays. The antiviral effects of 2'-FL/3-FL were further confirmed by pseudoviral assays with three SARS-Cov-2 mutants, with a stronger inhibition effect of 2'-FL than 3-FL. Then, 2'-FL/3-FL were studied with molecular docking and microscale thermophoresis analysis, showing that the binding sites of 2'-FL on RBD were involved in receptor binding, in addition to a tighter bond between them, thus enabling 2'-FL to be more effective than 3-FL. Moreover, the immunomodulation effect of 2'-FL was preliminary evaluated and confirmed in a human alveolus chip. These results would open up possible applications of 2'-FL for the prevention of SARS-CoV-2 infections by competitive binding inhibition.

Association between ABO blood groups and SARS-CoV-2 infection in blood donors of Puglia region

This is an observational multicentric cross-sectional study aiming at assessing the association between ABO blood groups and SARS-CoV-2 seroprevalence among the blood donors in Puglia region. Data on ABO and Rh blood groups and demographic characteristics were obtained from Blood Bank Information System. All donors were screened for SARS-CoV-2 IgG antibodies. Comparison of seroprevalence among blood groups and the association between the recorded variables and seroprevalence were evaluated. A total of 35,709 donors from 22 centers were included, with a seroprevalence of 6.8%. The distribution of ABO phenotypes was blood type O (46.8%), A (34.0%), B (14.7%), and AB (4.5%). Among the 2416 donors reactive for SARS-CoV-2 IgG, the prevalent phenotype was blood type O (43.1%), followed by A (37.7%), B (14.2%), and AB (5%). The seroprevalence of phenotype A and AB was 7.5%, followed by B (6.5%) and O (6.2%). According to the adjusted analysis, there was an increase in seroprevalence in groups A and AB, compared to group O, and an increase in males compared to females. A possible effect modification was observed after stratifying for sex (p = 0.0515). A significantly lower prevalence of blood type O was found compared to A and AB, whereas no association was observed between Rh factor and seroprevalence. We hypothesized that the A antigen present in blood type A and AB can play a role in the binding of SARS-CoV-2 to ACE2 receptors, resulting in an increased risk of infection. Furthermore, natural anti-A/anti-B antibodies produced in group O could block viral adhesion to cells and explain a lower risk of infection.

Blood group A enhances SARS-CoV-2 infection

Among the risk factors for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), ABO(H) blood group antigens are among the most recognized predictors of infection. However, the mechanisms by which ABO(H) antigens influence susceptibility to COVID-19 remain incompletely understood. The receptor-binding domain (RBD) of SARS-CoV-2, which facilitates host cell engagement, bears significant similarity to galectins, an ancient family of carbohydrate-binding proteins. Because ABO(H) blood group antigens are carbohydrates, we compared the glycan-binding specificity of SARS-CoV-2 RBD with that of galectins. Similar to the binding profile of several galectins, the RBDs of SARS-CoV-2, including Delta and Omicron variants, exhibited specificity for blood group A. Not only did each RBD recognize blood group A in a glycan array format, but each SARS-CoV-2 virus also displayed a preferential ability to infect blood group A-expressing cells. Preincubation of blood group A cells with a blood group-binding galectin specifically inhibited the blood group A enhancement of SARS-CoV-2 infection, whereas similar incubation with a galectin that does not recognize blood group antigens failed to impact SARS-CoV-2 infection. These results demonstrated that SARS-CoV-2 can engage blood group A, providing a direct link between ABO(H) blood group expression and SARS-CoV-2 infection.

A large cohort study of the effects of Lewis, ABO, 13 other blood groups, and secretor status on COVID-19 susceptibility, severity, and long COVID-19

BACKGROUND

Previous studies have reported Blood type O to confer a lower risk of SARS-CoV-2 infection, while secretor status and other blood groups have been suspected to have a similar effect as well.

STUDY DESIGN AND METHODS

To determine whether any other blood groups influence testing positive for SARS-CoV-2, COVID-19 severity, or prolonged COVID-19, we used a large cohort of 650,156 Danish blood donors with varying available data for secretor status and blood groups ABO, Rh, Colton, Duffy, Diego, Dombrock, Kell, Kidd, Knops, Lewis, Lutheran, MNS, P1PK, Vel, and Yt. Of these, 36,068 tested positive for SARS-CoV-2 whereas 614,088 tested negative between 2020-02-17 and 2021-08-04. Associations between infection and blood groups were assessed using logistic regression models with sex and age as covariates.

RESULTS

The Lewis blood group antigen Le^a displayed strongly reduced SARS-CoV-2 susceptibility OR 0.85 CI[0.79-0.93] p < .001. Compared to blood type O, the blood types B, A, and AB were found more susceptible toward infection with ORs 1.1 CI[1.06-1.14] p < .001, 1.17 CI[1.14-1.2] p < .001, and 1.2 CI[1.14-1.26] p < .001, respectively. No susceptibility associations were found for the other 13 blood groups investigated. There was no association between any blood groups and COVID-19 hospitalization or long COVID-19. No secretor status associations were found.

DISCUSSION

This study uncovers a new association to reduced SARS-CoV-2 susceptibility for Lewis type Le^a and confirms the previous link to blood group O. The new association to Le^a could be explained by a link between mucosal microbiome and SARS-CoV-2.

Detailed stratified GWAS analysis for severe COVID-19 in four European populations

Given the highly variable clinical phenotype of Coronavirus disease 2019 (COVID-19), a deeper analysis of the host genetic contribution to severe COVID-19 is important to improve our understanding of underlying disease mechanisms. Here, we describe an extended genome-wide association meta-analysis of a well-characterized cohort of 3255 COVID-19 patients with respiratory failure and 12 488 population controls from Italy, Spain, Norway and Germany/Austria, including stratified analyses based on age, sex and disease severity, as well as targeted analyses of chromosome Y haplotypes, the human leukocyte antigen region and the SARS-CoV-2 peptidome. By inversion imputation, we traced a reported association at 17q21.31 to a ~0.9-Mb inversion polymorphism that creates two highly differentiated haplotypes and characterized the potential effects of the inversion in detail. Our data, together with the 5th release of summary statistics from the COVID-19 Host Genetics Initiative including non-Caucasian individuals, also identified a new locus at 19q13.33, including NAPSA, a gene which is expressed primarily in alveolar cells responsible for gas exchange in the lung.

FUT2 gene as a genetic susceptible marker of infectious diseases: A Review

Some blood group antigens are reported as a susceptibility marker for some diseases. For instance, HBGA (Histo-blood group antigen) which is controlled by gene FUT2 also considered as a susceptible marker. The FUT2 gene which exhibits the expression of alpha-1, 2-L-fucosyltransferase enzyme also leads to HBGA expression for the gut, and it provides a composition of the phenotypical profile that exists in some populations with unique histories of evolution and it can be considered as a marker of the genetic population. It is found to have an association with many diseases which is discussed in this review. Polymorphic mutations are known to inhibit and reduce its function which are population specific. Detailed understanding and deeper knowledge of its role in the pathogenesis and prevention of many diseases is required. FUT2 may also have a potential role in the case of COVID-19 as a susceptible marker due to its association with respiratory diseases and the ABO blood group. There is an utmost need for this kind of review knowing its importance and owing to limited collective information.

mGWAS-Explorer: Linking SNPs, Genes, Metabolites, and Diseases for Functional Insights

Tens of thousands of single-nucleotide polymorphisms (SNPs) have been identified to be significantly associated with metabolite abundance in over 65 genome-wide association studies with metabolomics (mGWAS) to date. Obtaining mechanistic or functional insights from these associations for translational applications has become a key research area in the mGWAS community. Here, we introduce mGWAS-Explorer, a user-friendly web-based platform to help connect SNPs, metabolites, genes, and their known disease associations via powerful network visual analytics. The application of the mGWAS-Explorer was demonstrated using a COVID-19 and a type 2 diabetes case studies.

Association of ABO blood group with in-hospital adverse outcome and long term persistent symptoms of COVID-19 infection: A single-center longitudinal observational study

Background and Aims

There are gaps in knowledge regarding the association between the ABO blood group and coronavirus disease 2019 (COVID-19) immediate and long-term outcomes. We aimed to investigate the association of ABO blood group with COVID-19 in-hospital adverse outcomes and to determine whether ABO blood group is associated with post-COVID-19 persistent symptoms.

Methods

This was a single-center longitudinal observational study that included patients who presented with symptoms suggestive of COVID-19 infection and a positive test for COVID-19 and were able to attend the out-patient clinic after 6 months following acute COVID-19. The main outcomes were intensive care unit admission, the requirement for respiratory support, in-hospital death, and persistent symptoms. χ 2 test and regression analysis were used to analyze the collected data.

Results

A total of 169 patients were enrolled for the assessment of in-hospital adverse outcomes of whom 86 patients were included for the assessment of persistent symptoms after the exclusion of deceased patients or patients not attended the out-patient clinic. Patients with blood group B had higher prevalence of in-hospital death compared to blood group O (39% vs. 13%, p = 0.01) and this persisted after adjusting for sex (odds ratio, OR [confidence interval, CI] = 1.4 [1.1-2.1], p = 0.04), while patients with blood group AB had higher prevalence of requiring respiratory support than blood group O (54% vs. 10%, p = 0.02) and this persisted after adjusting for age (OR [CI] = 1.5 [1.1-2.3], p = 0.02). Concerning the association of ABO blood group and long-term symptoms, blood group AB showed a higher prevalence of palpitation (p < 0.001) and dizziness (p = 0.02) than other blood groups.

Conclusions

Blood groups AB and B are significantly associated with respiratory support use and in-hospital death, respectively, compared to blood group O. Blood group AB is significantly associated with persistent palpitation and dizziness compared to other blood groups.

Human Milk Oligosaccharides: Potential Applications in COVID-19

Coronavirus disease 2019 (COVID-19) pandemic caused by severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2) has become a global health crisis with more than four million deaths worldwide. A substantial number of COVID-19 survivors continue suffering from long-COVID syndrome, a long-term complication exhibiting chronic inflammation and gut dysbiosis. Much effort is being expended to improve therapeutic outcomes. Human milk oligosaccharides (hMOS) are non-digestible carbohydrates known to exert health benefits in breastfed infants by preventing infection, maintaining immune homeostasis and nurturing healthy gut microbiota. These beneficial effects suggest the hypothesis that hMOS might have applications in COVID-19 as receptor decoys, immunomodulators, mucosal signaling agents, and prebiotics. This review summarizes hMOS biogenesis and classification, describes the possible mechanisms of action of hMOS upon different phases of SARS-CoV-2 infection, and discusses the challenges and opportunities of hMOS research for clinical applications in COVID-19.

ABO Blood Groups and the Incidence of Complications in COVID-19 Patients: A Population-Based Prospective Cohort Study

After a COVID-19 outbreak in the Falles festival of Borriana (Spain) during March 2020, a cohort of patients were followed until October 2020 to estimate complications post-COVID-19, considering ABO blood groups (ABO). From 536 laboratory-confirmed cases, 483 completed the study (90.1%) carried by the Public Health Center of Castelló and the Emergency and Microbiology and Clinical Analysis of Hospital de la Plana Vila-real. The study included ABO determination and telephone interviews of patients. The participants had a mean age of 37.2 ± 17.1 years, 300 females (62.1%). ABO were O (41.4%), A (45.5%), B (9.1%), and AB (3.9%). We found no difference in the incidence of COVID-19 infections. A total of 159 (32.9%) patients reported one or more post-COVID-19 complications with divergent incidences after adjustment: O (32.3%), A (32.6%), B (54.1%), and AB (27.6%); B groups had more complications post-COVID-19 when compared with O group (adjusted relative risk [aRR] 95% confidence interval [CI] 1.68, 95% CI 1.24–2.27), and symptoms of fatigue (1.79, 95% CI 1.08–2.95), myalgia (2.06, 95% CI 1.10–3.84), headache (2.61, 95% CI 1.58–4.31), and disorder of vision (4.26 95% CI 1.33–13.60). In conclusion, we observed significant differences in post-COVID-19 complications by ABO, with a higher incidence in B group. Additional research is justified to confirm our results.

Blood group type A secretors are associated with a higher risk of COVID-19 cardiovascular disease complications

The SARS-CoV-2 virus causes COVID-19, an infection capable of causing severe disease and death but which can also be asymptomatic or oligosymptomatic. We investigated whether ABO blood group or secretor status was associated with COVID-19 severity. We investigated secretor status because expression of ABO glycans on secreted proteins and non-erythroid cells are controlled by a fucosyltransferase (FUT2), and inactivating FUT2 mutations result in a non-secretor phenotype which protects against some viral infections. Data combined from healthcare records and our own laboratory tests (n = 275) of hospitalized SARS-CoV-2 polymerase chain reaction positive patients confirmed higher than expected numbers of blood group A individuals compared to O (RR = 1.24, CI 95% [1.05, 1.47], p = 0.0111). There was also a significant association between group A and COVID-19-related cardiovascular complications (RR = 2.56, CI 95% [1.43, 4.55], p = 0.0011) which is independent of gender. Molecular analysis revealed that group A non-secretors are significantly less likely to be hospitalized than secretors. Testing of convalescent plasma donors, among whom the majority displayed COVID-19 symptoms and only a small minority required hospitalization, group A non-secretors were slightly over-represented. Our findings showed that group A non-secretors are not resistant to infection by SARS-CoV-2, but are more likely to experience a less severe form of associated disease.