The effect of ABO blood group and antibody class on the risk of COVID-19 infection and severity of clinical outcomes

Assessment of the COVID-19 pandemic progression in Ecuador through seroprevalence analysis of anti-SARS-CoV-2 IgG/IgM antibodies in blood donors

Introduction

Coronavirus Disease 2019 (COVID-19) is a severe respiratory illness caused by the RNA virus SARS-CoV-2. Globally, there have been over 759.4 million cases and 6.74 million deaths, while Ecuador has reported more than 1.06 million cases and 35.9 thousand deaths. To describe the COVID-19 pandemic impact and the vaccinations effectiveness in a low-income country like Ecuador, we aim to assess the seroprevalence of IgG and IgM antibodies against SARS-CoV-2 in a sample from healthy blood donors at the Cruz Roja Ecuatoriana.

Methods

The present seroprevalence study used a lateral flow immunoassay (LFIA) to detect anti-SARS-CoV-2 IgG and IgM antibodies in months with the highest confirmed case rates (May 2020; January, April 2021; January, February, June, July 2022) and months with the highest vaccination rates (May, June, July, August, December 2021) in Quito, Ecuador. The IgG and IgM seroprevalence were also assessed based on sex, age range, blood type and RhD antigen type. The sample size was 8,159, and sampling was performed based on the availability of each blood type.

Results

The results showed an overall IgG and IgM seroprevalence of 47.76% and 3.44%, respectively. There were no differences in IgG and IgM seroprevalences between blood groups and sex, whereas statistical differences were found based on months, age range groups, and RhD antigen type. For instance, the highest IgG seroprevalence was observed in February 2022 and within the 17-26 years age range group, while the highest IgM seroprevalence was in April 2021 and within the 47-56 years age range group. Lastly, only IgG seroprevalence was higher in RhD+ individuals while IgM seroprevalence was similar across RhD types.

Discussion

This project contributes to limited data on IgG and IgM antibodies against SARS-CoV-2 in Ecuador. It suggests that herd immunity may have been achieved in the last evaluated months, and highlights a potential link between the RhD antigen type and COVID-19 susceptibility. These findings have implications for public health strategies and vaccine distribution not only in Ecuador but also in regions with similar characteristics.

Effect of ABO blood group on the severity and clinico-pathological parameters of COVID-19

Background and Objective

The COVID-19 pandemic has highlighted the need to understand the factors affecting disease severity. Prior research has indicated the potential roles of the ABO blood group system in disease susceptibility and progression. Our objective was to investigate the association between ABO Blood groups and the severity of COVID-19 and clinicopathological parameters.

Methods

An analytical cross-sectional study was conducted across three locations of Ziauddin University Hospital, including COVID-19 outpatient departments (OPDs), wards, and intensive care units (ICUs) from May 2020 to December 2020.The study utilized a non-probability convenient sampling technique with a sample size of 120 PCR-positive adult patients, as calculated by OpenEpi with a 95% confidence interval. Patients were excluded if they were under 14, intellectually impaired, post-chemotherapy or radiotherapy, or had a malignant condition. Disease severity was determined based on clinicopathological parameters and associated with blood group data using ANOVA and Chi-square tests in SPSS version 21.

Results

A significant association was found between the ABO blood groups and COVID-19 severity. Blood group-A was notably overrepresented in patients with severe COVID-19 and correlated with higher inflammatory markers and coagulation parameters.

Conclusion

ABO blood group, particularly Blood Group-A significantly associates with the severity of COVID-19. This finding suggests the potential utility of ABO blood group typing as a predictive marker for disease severity, which could contribute to personalized patient management strategies. Further research is necessary to understand the mechanisms underlying this association.

Impact of COVID status and blood group on complications in patients in hemorrhagic shock

Objective

Among critically injured patients of various blood groups, we sought to compare survival and complication rates between COVID-19-positive and COVID-19-negative cohorts.

Background

SARS-CoV-2 infections have been shown to cause endothelial injury and dysfunctional coagulation. We hypothesized that, among patients with trauma in hemorrhagic shock, COVID-19-positive status would be associated with increased mortality and inpatient complications. As a secondary hypothesis, we suspected group O patients with COVID-19 would experience fewer complications than non-group O patients with COVID-19.

Methods

We evaluated all trauma patients admitted 4/2020-7/2020. Patients 16 years or older were included if they presented in hemorrhagic shock and received emergency release blood products. Patients were dichotomized by COVID-19 testing and then divided by blood groups.

Results

3281 patients with trauma were evaluated, and 417 met criteria for analysis. Seven percent (29) of patients were COVID-19 positive; 388 were COVID-19 negative. COVID-19-positive patients experienced higher complication rates than the COVID-19-negative cohort, including acute kidney injury, pneumonia, sepsis, venous thromboembolism, and systemic inflammatory response syndrome. Univariate analysis by blood groups demonstrated that survival for COVID-19-positive group O patients was similar to that of COVID-19-negative patients (79 vs 78%). However, COVID-19-positive non-group O patients had a significantly lower survival (38%). Controlling for age, sex and Injury Severity Score, COVID-19-positive patients had a greater than 70% decreased odds of survival (OR 0.28, 95% CI 0.09 to 0.81; p=0.019).

Conclusions

COVID-19 status is associated with increased major complications and 70% decreased odds of survival in this group of patients with trauma. However, among patients with COVID-19, blood group O was associated with twofold increased survival over other blood groups. This survival rate was similar to that of patients without COVID-19.

Correlation between ABO blood type, susceptibility to SARS-CoV-2 infection and COVID-19 disease severity: A systematic review

OBJECTIVES

To verify the association between the ABO blood type and the risk of SARS-CoV-2 infection and COVID-19 disease severity.

METHODS

This review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA), using the 2020 PRISMA Checklist and flow diagram, and articles selected for review were analyzed using the Newcastle-Ottawa Quality Rating Scale. The research question was: "Would the ABO blood group influence the risk of infection and clinical course of patients infected with SARS-CoV-2?", The following databases were used: Embase, PubMed, Virtual Health Library (VHL), Web of Science, ScienceDirect and Scopus. The protocol for this review was registered in the Prospective Register of Systematic Reviews (PROSPERO), number CRD42021245945.

RESULTS

We found 798 articles across PubMed, Embase, Scopus, Web of Science, Science Direct and Virtual Health Library and 54 articles were included in the final analysis. Among 30 studies evaluating the risk of COVID-19 infection, 21 found significant correlations with ABO blood groups, 14 of them revealing an increased risk in blood group A and 15 studies showing a decreased risk in blood group O. Most studies found no significant correlation with disease severity or mortality.

CONCLUSION

The qualitative assessment of available information suggests that blood group A may be a risk factor for COVID-19 infection and that blood group O may have a protective effect. We were unable to determine a clear association between the ABO blood group and mortality. These conclusions are based on highly heterogenous evidence.

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.

Vitamin D status and blood group among severe COVID-19 patients

Objective

Prognosis of COVID-19 infection has been indicated to be associated with vitamin D status and ABO blood group. However, owing to discrepancies and an increased number of cases globally, the findings remain unclear. This study aimed to evaluate the association between vitamin D and ABO blood group systems in patients with severe COVID-19.

Methods

In this cross-sectional study, COVID-19 patients referred to two hospitals in the capital of Iran, Tehran, admitted to the ICU ward due to the severity of COVID-19 were evaluated. Serum vitamin D and ABO levels were evaluated in these patients. The data obtained were statistically analyzed using SPSSv24.

Results

Of 305 patients, 33.1% patients had O+ blood type, 27.8% had A+ blood type and 22.4% had B+ blood type. Vitamin D deficiency was significantly associated with a mortality rate among these patients, P<0.05. The blood group of the patients was not correlated with mortality. Thirty-seven percent of the patients in the study died because of COVID-19.

Conclusion

In our study population, mortality due to COVID-19 was significantly associated with vitamin D deficiency but not the ABO blood group. We recommend further studies in this regard that include more variable and detailed biochemical analysis.

Homozygous-Recessive Characteristics as a Biomarker of Predisposition for COVID-19

Coronavirus disease (COVID-19), a new form of severe acute respiratory syndrome, has caused a global pandemic. The aim of this study was to analyze homozygous-recessive characteristics (HRC) in the group of COVID-19 patients, considering their gender, forms of the disease (mild and severe symptoms), risk factors: hypertension, diabetes mellitus type 2, hyperlipidemia, smoking habits, and the distribution of ABO blood group. Using the HRC test, we analyzed 20 HRCs in a sample of 321 individuals: 205 patients and 116 controls. The average HRC in patients was significantly higher than controls, as well as in patients with severe symptoms compared to patients with mild symptoms. The patients with higher HRC (cut-off ≤5.5) experienced a significantly increased risk of disease of 2.3 times (OR = 2.315, p < .0005). Our results indicate that the HRC test could be used as a screening in recognizing predisposition for COVID-19.

Blood-Type-A is a COVID-19 infection and hospitalization risk in a Turkish cohort

We have shown in an ethnically homogenous Turkey cohort with more than six thousand cases and 25 thousand controls that ABO blood types that contain anti-A antibody (O and B) are protective against COVID-19 infection and hospitalization, whereas those without the anti-A antibody (A and AB) are risks. The A + AB frequency increases from 54.7 % in uninfected controls to 57.6 % in COVID-19 outpatients, and to 62.5 % in COVID-19 inpatients. The odds-ratio (OR) for lacking of anti-A antibody risk for infection is 1.16 (95 % confidence interval (CI) 1.1-1.22, and Fisher test p-value 1.8 × 10^-7). The OR for hospitalization is 1.23 (95 %CI 1.06-1.42, Fisher test p-value 0.005). A linear regression treating controls, outpatients, inpatients as three numerical levels over anti-A antibody leads to a p-value of 5.9 × 10^-9. All these associations remain to be statistically significant after conditioning over age, even though age itself is a risk for both infection and hospitalization. We also attempted to correct the potential effect from vaccination, even though vaccination information is not available, by using the date of the data collection as a surrogate to vaccination status. Although no significant association between infection/hospitalization with Rhesus blood system was found, forest plots are used to illustrate possible trends.

Association of blood group with COVID-19 disease susceptibility and severity in Saudi Arabia

BACKGROUND

Novel SARS-CoV-2 (COVID-19) virus has rapidly spread worldwide and was declared a pandemic, making identifying and prioritizing individuals most at risk a critical challenge. The literature describes an association between blood groups and the susceptibility to various viral infections and their severity. Knowing if a specific blood group has more susceptibility to COVID-19 may help improve understanding the pathogenesis and severity of the disease. We aimed to assess the association between ABO/RhD and COVID-19 susceptibility and severity, and to compare results with similar studies in Saudi Arabia.

STUDY DESIGN AND METHODS

This study was conducted between March and October 2021 on 600 patients confirmed positive for COVID-19 infection. Patients' data were collected and analyzed. As a control, 8423 healthy blood donors were enrolled as a sample representative of the population for blood group distribution.

RESULTS

More individuals had blood group B in the COVID-19 group in comparison with the control group (24.2% vs. 18%), The opposite was observed among individuals of group O (39.5% vs. 47.3%). The B blood group was predictive of higher risk of mortality. No significant difference in the distribution of RhD was observed between the COVID-19 and the control groups. Neither ABO nor RhD was significantly associated with the severity of COVID-19.

DISCUSSION

Although there was no significant association with the disease severity, the B blood group may be associated with a higher risk for COVID-19 infection. Further studies with a larger sample size are necessary to evaluate this correlation.

Blood types (ABO/Rhesus) and SARS-CoV-2 infection: a retrospective, cross-sectional study in 2828 healthcare workers

Background: The authors aimed to investigate the relationship between ABO/Rhesus blood types and the risk of SARS-CoV-2 infection and hospitalization in healthcare workers (HCWs). Materials & methods: This study compared HCWs with (n = 510) and without (n = 2318) SARS-CoV-2 infection. Risk factors for SARS-CoV-2 infection and hospitalization in HCWs were shown as odds ratios with 95% CI. Results: Blood group O was found to be protective by 20% from the risk of developing SARS-CoV-2 infection in HCWs (29.2 vs 33.8%; odds ratio: 0.808; 95% CI: 0.655–0.996; p = 0.045). The prevalence of group O was lower in hospitalized patients than in outpatients (25 vs 29.5%; p = 0.614). Conclusion: These findings suggest that blood groups are associated with the development of SARS-CoV-2 infection.

In this study, the relationship between ABO blood groups and the development of SARS-CoV-2 infection was investigated in healthcare workers (HCWs) working in a tertiary hospital. A total of 2828 HCWs were included in the study. Of those, 510 (18%) had SARS-CoV-2 infection. The prevalence of blood group O was 33% (n = 933). The prevalence of group O was lower in hospitalized patients than in outpatients (25 vs 29.5%; p = 0.614). Further analysis revealed that blood group O was associated with a decreased risk of developing SARS-CoV-2 infection in HCWs by up to 20%.

In the study of Copur et al., #bloodgroupO was found to be protective by 20% from the risk of developing #SARS-CoV-2 #infection in #healthcareworkers.

Correlation of SARS-CoV-2 infection severity with ABO blood groups and RhD antigen: a case-control study

Objective

The role of ABO types and RhD antigen in coronavirus disease 2019 (COVID-19) severity has been investigated in several recent studies. Thus, the objective of this study was to identify the relationship of ABO and RhD types with symptomatic COVID-19 disease and determine the groups associated with an increased risk of hospitalization.

Methods

This observational case-control study was performed in 530 Iraqi-Kurdish patients with COVID-19. Among them, 184 were severe cases that required hospitalization, while 346 were mild to moderate cases that were treated at home. ABO and RhD antigen groups were compared between cases and 1698 control records from 1 year before the pandemic. The diagnosis of COVID-19 was based on real-time polymerase chain reaction tests and high-resolution chest computed tomography scans with the typical clinical presentation.

Results

There were no significant differences in ABO and RhD antigen distributions between the COVID-19 cases and non-COVID controls. No ABO group was associated with the risk of hospitalization as a marker of the severity of infection.

Conclusions

There was no significant association between symptomatic COVID-19 disease and any ABO group or RhD antigen type. No impact of ABO groups on hospitalization was documented.

ABO blood group and link to COVID-19: A comprehensive review of the reported associations and their possible underlying mechanisms

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.

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.

Host polymorphisms and COVID-19 infection

Coronavirus disease (COVID-19) is an infectious disease caused by a newly discovered coronavirus, severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). There is growing evidence that host genetics play an important role in COVID-19 severity. Based on current knowledge about the human protein machinery for SARS-CoV-2 entry, the host innate immune response, and virus-host interactions, the potential effects of human genetic polymorphisms, which may contribute to clinical differences in SARS-CoV-2 pathogenesis, may help to determine the individual risk for COVID-19 infection and outcome.

ABO Blood Group Incompatibility Protects Against SARS-CoV-2 Transmission

ABO blood groups appear to be associated with the risk of SARS-CoV-2 infection, but the underlying mechanisms and their real importance remain unclear. Two hypotheses have been proposed: ABO compatibility-dependence (neutralization by anti-ABO antibodies) and ABO-dependent intrinsic susceptibility (spike protein attachment to histo-blood group glycans). We tested the first hypothesis through an anonymous questionnaire addressed to hospital staff members. We estimated symptomatic secondary attack rates (SAR) for 333 index cases according to spouse ABO blood group compatibility. Incompatibility was associated with a lower SAR (28% vs. 47%; OR 0.43, 95% CI 0.27–0.69), but no ABO dependence was detected in compatible situations. For the second hypothesis, we detected no binding of recombinant SARS-CoV-2 RBD to blood group-containing glycans. Thus, although no intrinsic differences in susceptibility according to ABO blood type were detected, ABO incompatibility strongly decreased the risk of COVID-19 transmission, suggesting that anti-ABO antibodies contribute to virus neutralization.

ABO blood grouping and COVID-19: a hospital-based study in Eastern India

Background

Blood group has been stated to be one of the risk factors associated with viral diseases like dengue, hepatitis virus, Norwalk virus and even the coronavirus associated with 2003 severe acute respiratory syndrome (SARS) outbreak. In addition, anti-A antibodies in experimental models have been shown to inhibit the interaction between coronavirus and angiotensin converting enzyme (ACE) receptor of the host target cell, the major receptor involved in viral pathogenesis. Thus, several workers propose an association between ABO blood type and coronavirus disease- 2019 (COVID-19) disease in many previous studies. The present study was undertaken in the Eastern part of India in line with these authors to study the association of ABO blood group of patients with COVID susceptibility and severity.

Methods

This is a retrospective study over a period of 6 months from June 2020 to November 2020 where patients who underwent quantitative real-time polymerase chain reaction (qRT-PCR) test for SARS-COV2 and having a recorded patient blood group type were considered. The qRT-PCR positive admitted cases were considered as cases, and qRT-PCR negative cases were considered as controls. Data were entered in Microsoft Excel format and analyzed by statistical method to obtain association.

Results

Consecutively obtained 5000 qRT-PCR positive patients (cases) and 11,700 (controls) were included in the present study. The mean age of cases was higher (54.24 vs. 34. 67) than the controls. Among the cases, the highest number (2379; 47.6%) of samples belonged to A blood group followed by B (1278; 25.6%) while among the control group O blood group had the highest prevalence (4215; 36%). Blood group A had a higher odd of testing positive (Odds ratio-2.552; CI 2.381-2.734; p < 0.0001) than all other blood groups. A blood group is also associated with higher risk of ICU admission (Odds ratio- 1.699; 95% CI 1.515-1.905) and 65.3% of this group is also associated with high viral load which gives an indication of higher disease severity.

Conclusion

Blood group A is associated with an increased susceptibility to COVID 19 infection than other blood groups. Cases of this blood group are also associated with more critical care needs and a higher viral load on testing.

Correlation between ABO Blood Group Phenotype and the Risk of COVID-19 Infection and Severity of Disease in a Saudi Arabian Cohort

BACKGROUND

Disease severity among patients infected with SARS-CoV-2 varies remarkably. Preliminary studies reported that the ABO blood group system confers differential viral susceptibility and disease severity caused by SARS-CoV-2. Thus, differences in ABO blood group phenotypes may partly explain the observed heterogeneity in COVID-19 severity patterns, and could help identify individuals at increased risk. Herein, we explored the association between ABO blood group phenotypes and COVID-19 susceptibility and severity in a Saudi Arabian cohort.

METHODS

In this retrospective cohort study, we performed ABO typing on a total of 373 Saudi patients infected with SARS-CoV-2 and conducted association analysis between ABO blood group phenotype and COVID-19 infection severity. We then performed gender-stratified analysis by dividing the participating patients into two groups by gender, and classified them according to age.

RESULTS

The frequencies of blood group phenotypes A, B, AB and O were 27.3, 23.6, 5.4 and 43.7%, respectively. We found that blood group phenotype O was associated with a lower risk of testing positive for COVID-19 infection (OR 0.76 95% CI 0.62-0.95, p = 0.0113), while blood group phenotype B was associated with higher odds of testing positive (OR 1.51 95% CI 1.17-1.93, p = 0.0009). However, blood group phenotype B was associated with increased risk in the mild and moderate group but not the severe COVID-19 infection group. Blood group phenotype O was protective in all severity groups.

CONCLUSION

Our findings provide evidence that blood group phenotype B is a risk for COVID-19 disease while blood group phenotype O is protective from COVID-19 infection. However, further studies are necessary to validate these associations in a larger sample size and among individuals of different ethnic groups.

The human gut symbiont Ruminococcus gnavus shows specificity to blood group A antigen during mucin glycan foraging: Implication for niche colonisation in the gastrointestinal tract

The human gut symbiont Ruminococcus gnavus displays strain-specific repertoires of glycoside hydrolases (GHs) contributing to its spatial location in the gut. Sequence similarity network analysis identified strain-specific differences in blood-group endo-β-1,4-galactosidase belonging to the GH98 family. We determined the substrate and linkage specificities of GH98 from R. gnavus ATCC 29149, RgGH98, against a range of defined oligosaccharides and glycoconjugates including mucin. We showed by HPAEC-PAD and LC-FD-MS/MS that RgGH98 is specific for blood group A tetrasaccharide type II (BgA II). Isothermal titration calorimetry (ITC) and saturation transfer difference (STD) NMR confirmed RgGH98 affinity for blood group A over blood group B and H antigens. The molecular basis of RgGH98 strict specificity was further investigated using a combination of glycan microarrays, site-directed mutagenesis, and X-ray crystallography. The crystal structures of RgGH98 in complex with BgA trisaccharide (BgAtri) and of RgGH98 E411A with BgA II revealed a dedicated hydrogen network of residues, which were shown by site-directed mutagenesis to be critical to the recognition of the BgA epitope. We demonstrated experimentally that RgGH98 is part of an operon of 10 genes that is overexpresssed in vitro when R. gnavus ATCC 29149 is grown on mucin as sole carbon source as shown by RNAseq analysis and RT-qPCR confirmed RgGH98 expression on BgA II growth. Using MALDI-ToF MS, we showed that RgGH98 releases BgAtri from mucin and that pretreatment of mucin with RgGH98 confered R. gnavus E1 the ability to grow, by enabling the E1 strain to metabolise BgAtri and access the underlying mucin glycan chain. These data further support that the GH repertoire of R. gnavus strains enable them to colonise different nutritional niches in the human gut and has potential applications in diagnostic and therapeutics against infection.

The association of ABO blood group with the asymptomatic COVID-19 cases in India

The COVID-19 pandemic resulted in multiple waves of infection worldwide. The large variations in case fatality rate among different geographical regions suggest that the human susceptibility against this virus varies substantially. Several studies from different parts of the world showed a significant association of ABO blood group and COVID-19 susceptibility. It was demonstrated that individuals with blood group O are at the lower risk of coronavirus infection. To establish the association of ABO blood group in SARS-CoV-2 susceptibility, we for the first time analysed SARS-CoV-2 neutralising antibodies among 509 individuals, collected from three major districts of Eastern Uttar Pradesh region of India. Interestingly, we found neutralising antibodies in a significantly higher percentage of people with blood group AB (0.36) followed by B (0.31), A (0.22) and lowest in people with blood group O (0.11). We further estimated that people with blood group AB are at comparatively higher risk of infection than other blood groups. Thus, among the asymptomatic SARS-CoV-2 recovered people blood group AB has highest, whilst individuals with blood group O has lowest risk of infection.

Association of ABO and Rh Blood Group in Susceptibility, Severity, and Mortality of Coronavirus Disease 2019: A Hospital-Based Study From Delhi, India

Background

ABO and Rh blood group systems are associated with many diseases including cancerous, infectious, non-infectious, bacterial and viral diseases. Studies have shown association of blood groups A and O with higher and lower odds for coronavirus disease 2019 positivity, respectively.

Methods

This is a single-center, retrospective study conducted at Sir Ganga Ram Hospital, Delhi. We investigated the association of ABO and Rh blood groups with susceptibility to coronavirus disease 2019 infection, severity of disease, recovery period, and mortality of patients. Patients were enrolled from April 8, 2020 to October 4, 2020. A total of 2,586 real-time PCR (RT-PCR)-confirmed coronavirus disease 2019 (COVID-19) patients were recruited. Data was analyzed using chi-square test, odds ratio, and Mann–Whitney test to determine the association of blood groups.

Results

In the 2,586 COVID-19-infected patients, the frequencies of A, B, O, and AB were 29.93%, 41.80%, 21.19%, and 7.98%, respectively. Of the patients, 98.07% were Rh positive. Blood group A (odds ratio, 1.53; CI, 1.40–1.66; p < 0.001) and B (odds ratio, 1.15; CI, 1.06–1.24; p < 0.001) is observed to be significantly associated with COVID-19 susceptibility, whereas blood group O (odds ratio, 0.65; CI, 0.59–0.71; p < 0.001) and AB (odds ratio, 0.66; CI, 0.59–0.71; p < 0.001) have low risk of COVID-19 infection.

Conclusion

A, B, and Rh+ are found to be more susceptible to COVID-19 infection, whereas blood groups O, AB, and Rh− are at a lower risk of COVID-19 infection. No association was found between blood groups and susceptibility to severity of disease and mortality.

COVID-19 Is a Multi-Organ Aggressor: Epigenetic and Clinical Marks

The progression of coronavirus disease 2019 (COVID-19), resulting from a severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, may be influenced by both genetic and environmental factors. Several viruses hijack the host genome machinery for their own advantage and survival, and similar phenomena might occur upon SARS-CoV-2 infection. Severe cases of COVID-19 may be driven by metabolic and epigenetic driven mechanisms, including DNA methylation and histone/chromatin alterations. These epigenetic phenomena may respond to enhanced viral replication and mediate persistent long-term infection and clinical phenotypes associated with severe COVID-19 cases and fatalities. Understanding the epigenetic events involved, and their clinical significance, may provide novel insights valuable for the therapeutic control and management of the COVID-19 pandemic. This review highlights different epigenetic marks potentially associated with COVID-19 development, clinical manifestation, and progression.

Association between blood groups and COVID-19 outcome in Iranian patients

Aim: Many factors have been speculated to explain the COVID-19 complex clinical phenotype. Due to the inconsistent data published on blood groups and COVID-19, we conducted a study on Iranian patients to further assess this association. Materials & methods: This retrospective study was conducted on data collected from confirmed COVID-19 hospitalized patients during March and December 2020 in a referral hospital for COVID-19, 5 Azar Hospital, Gorgan, north of Iran. A total of 1554 confirmed COVID-19 cases were enrolled in the study with blood group (ABO and Rh), demographic, and clinical data available. Results: Of 1554 patients, 1267 and 287 cases had recovered and deceased (due to COVID-19) outcomes, respectively. Most of the cases had O+ (29.6%), the least number had AB- (0.5%), and most of the deceased cases had O+ blood types (31.4%). Logistic regression analysis revealed that groups A- and B- had higher and groups B+, AB+, O+ and O- had lower odds of death than the A+ group. Conclusion: This study indicates that blood types may be related to the clinical outcome of COVID-19. Further studies with a large cohort for multiple people are required to validate this association.

ABO Blood Types and COVID-19: Spurious, Anecdotal, or Truly Important Relationships? A Reasoned Review of Available Data

Since the emergence of COVID-19, many publications have reported associations with ABO blood types. Despite between-study discrepancies, an overall consensus has emerged whereby blood group O appears associated with a lower risk of COVID-19, while non-O blood types appear detrimental. Two major hypotheses may explain these findings: First, natural anti-A and anti-B antibodies could be partially protective against SARS-CoV-2 virions carrying blood group antigens originating from non-O individuals. Second, O individuals are less prone to thrombosis and vascular dysfunction than non-O individuals and therefore could be at a lesser risk in case of severe lung dysfunction. Here, we review the literature on the topic in light of these hypotheses. We find that between-study variation may be explained by differences in study settings and that both mechanisms are likely at play. Moreover, as frequencies of ABO phenotypes are highly variable between populations or geographical areas, the ABO coefficient of variation, rather than the frequency of each individual phenotype is expected to determine impact of the ABO system on virus transmission. Accordingly, the ABO coefficient of variation correlates with COVID-19 prevalence. Overall, despite modest apparent risk differences between ABO subtypes, the ABO blood group system might play a major role in the COVID-19 pandemic when considered at the population level.