Role of vitamin D in modulating the immune response to SARS-CoV-2 and other coronavirus infections.

In recent years, new data have been obtained on the significant prevalence of vitamin D (VD) deficiency in the population, and knowledge about the role of vitamin D in the regulation of many physiological processes in the body, including the functioning of the immune system, has increased. The SARS-CoV-2 pandemic has further highlighted the issue of an adequate immune response in vitamin D deficiency. Objective of the review. To present and summarize the evidence on the role of VD in different parts of the immune response in COVID-19, to analyze available studies of the VD status effect on the course and outcome of COVID-19 in patients from different population groups. Material and methods. A search of domestic and foreign literature on the role of VD in the immune response in respiratory viral infections and SARS-CoV-2, as well as practical measures of VD-status correction in COVID-19, was performed. We used Scopus, Web of Science, PubMed, Google Scholar, eLibrary, and Cyberleninka databases. Results. Numerous clinical and observational studies have found an association between 25-hydroxyvitamin D levels, COVID-19 severity, and mortality. This association can be explained by the multifaceted role of vitamin D in the physiology of the human immune and endocrine systems. On the immunological side, the active form of VD promotes the secretion of antimicrobial peptides responsible for inhibiting viral replication and stimulates autophagy by increasing the level of Beclin1 protein and decreasing the level of mTOR protein regulating cellular homeostasis. It leads to the presentation of antigens followed by activation of the antiviral pathway of type I interferons. VD also stabilizes intercellular junctions, including those in the airway epithelium, reducing their permeability to pathogens, stimulates the activity of angiotensin-converting enzyme-2, whose receptors are a conduit for SARS-CoV-2 into cells, and several pathophysiological responses associated with the disease symptoms and acute lung injury. Adequate vitamin D status can provide significant benefits during the pandemic. Conclusion. To date, ideas about the role of vitamin D in regulating the immune response in respiratory infections have significantly expanded. However, its use in the complex preventive measures and adjuvant therapy of viral infections, including COVID-19, should be the subject of further scientific research.Copyright © 2023, Media Sphera Publishing Group. All rights reserved.

FETAL GROWTH RETARDATION AS A COMPLICATION OF POST-COVID ENDOTHELIITIS: CAUSES, CONSEQUENCES, WAYS OF PREVENTION.

The risk of fetal intrauterine growth retardation (IUGR) is increased in women who have experienced acute infections, as well as in pregnant women with gynecological pathology and endocrine diseases. A woman's lack of nutrition also makes a negative contribution to the development of IUGR. The frequency of IUGR in the population is very variable and depends on a number of reasons. In practically healthy pregnant women, IUGR is registered in 3-5% of cases, in case of complicated obstetric and gynecological diagnosis and complicated pregnancy - in 10-25%. Morphofunctional disorders in the chorion/placenta in pregnant women with COVID-19 on the background of post-covid endotheliitis are the main pathogenetic factor in the development of preeclampsia, ectopic pregnancy, antenatal fetal death, and impaired condition of the fetus and newborns. Sufficient saturation of the pregnant woman's body with the nitric oxide donor L-arginine and L-carnitine (main cofactor of fatty acid metabolism in cells) with the improvement of microcirculation and the correction of hypovolemic disorders in the fetoplacental complex can be considered one of the real ways to prevent IUGR in women in the post-covid period. A review of the scientific literature on pathogenesis, diagnosis, impact on the life and health of a newborn with IUGR in women after COVID-19, as well as the possibilities of medical correction of placental dysfunction during pregnancy was performed. This analysis and our own clinical experience allow us to state the fact that after a coronavirus infection during pregnancy, one of the frequent and threatening for the further development of the child is the formation of placental dysfunction and IUGR. One of the ways to prevent these conditions is to saturate the woman's body with the nitric oxide donor L-arginine from the stage of pre-gravid preparation, which will provide the opportunity for adequate angiogenesis and development of the embryo/fetus. In the case of additional risk factors, such as coronavirus disease, complex therapy blood (Rheosorbilact), in combination with a nitric oxide donor and L-carnitine as an endothelium-protective agent (Tivor-L).Copyright © 2022 Authors. All rights reserved.

Potential links between COVID-19 and periodontitis: a bioinformatic analysis based on GEO datasets.

BACKGROUND: 2019 Coronavirus disease (COVID-19) is an infectious disease caused by the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). The COVID-19 pandemic has already had a serious influence on human existence, causing a huge public health concern for countries all around the world. Because SARS-CoV-2 infection can be spread by contact with the oral cavity, the link between oral illness and COVID-19 is gaining traction. Through bioinformatics approaches, we explored the possible molecular mechanisms linking the COVID-19 and periodontitis to provide the basis and direction for future research. METHODS: Transcriptomic data from blood samples of patients with COVID-19 and periodontitis was downloaded from the Gene Expression Omnibus database. The shared differentially expressed genes were identified. The analysis of Gene Ontology, Kyoto Encyclopedia of Genesand Genomes pathway, and protein-protein interaction network was conducted for the shared differentially expressed genes. Top 5 hub genes were selected through Maximal Clique Centrality algorithm. Then mRNA-miRNA network of the hub genes was established based on miRDB database, miRTarbase database and Targetscan database. The Least absolute shrinkage and selection operator regression analysis was used to discover possible biomarkers, which were then investigated in relation to immune-related genes. RESULTS: Fifty-six shared genes were identified through differential expression analysis in COVID-19 and periodontitis. The function of these genes was enriched in regulation of hormone secretion, regulation of secretion by cell. Myozenin 2 was identified through Least absolute shrinkage and selection operator regression Analysis, which was down-regulated in both COVID-19 and periodontitis. There was a positive correlation between Myozenin 2 and the biomarker of activated B cell, memory B cell, effector memory CD4 T cell, Type 17 helper cell, T follicular helper cell and Type 2 helper cell. CONCLUSION: By bioinformatics analysis, Myozenin 2 is predicted to correlate to the pathogenesis and immune infiltrating of COVID-19 and periodontitis. However, more clinical and experimental researches are needed to validate the function of Myozenin 2.

A Case of Neuroretinitis Following COVID-19 Vaccination.

PURPOSE: To present a case of neuroretinitis following an mRNA COVID-19 vaccination. CASE REPORT: A 78-year-old healthy woman was presented with blurry vision in her left eye 1 day after receiving the third dose of the Pfizer-BioNTech COVID-19 vaccine. The ocular examination revealed an optic disc swelling and retinal thickening of the macula with subretinal fluid in the left eye. The fluorescein angiography revealed hyperfluorescence of the left optic disc. The neuroretinitis resolved gradually after taking azithromycin and prednisolone orally. CONCLUSIONS: This is the first report of unilateral neuroretinitis following COVID-19 vaccination, implying a potential association between the mRNA vaccine and neuroretinitis.

Epidemiological characteristics, clinical course, and laboratory investigation of pediatric COVID-19 patients in a tertiary care center in Saudi Arabia.

Background: Since the initial emergence of the novel SARS-CoV-2 coronavirus responsible for the 2019 coronavirus disease (COVID-19) pandemic, many studies have been exploring the nature and characteristics of this virus and its associated clinical manifestations. The present study aimed to describe the clinical presentation and outcomes of COVID-19 infections in pediatric patients. Methods: A retrospective review of findings associated with 143 pediatric patients (age <14 years) with a confirmed COVID-19 diagnosis who had undergone inpatient or outpatient treatment at King Faisal Specialist Hospital and Research Center in Riyadh, Saudi Arabia, between March 2020 and October 2020, was conducted. The analyzed data included patient demographic information, pre-existing medical conditions, symptoms, interventions, and outcomes. Results: The median age of this patient population was 7 years. Of these 143 patients, 67 (46.8%) had known pre-existing medical conditions including bronchial asthma (12.8%), chronic lung disease (CLD) (3%), congenital heart disease (CHD) (17%), primary immunodeficiencies (1.5%), malignancies (9.8%), and 7.5% were post-transplant patients. Thirty-seven patients (26%) were overweight or obese. Sixty-three of these patients (51%) were symptomatic, with the most common symptom being fever (55%). Ultimately, 45 patients (31%) required admission to the hospital, with a median duration of hospitalization of 9.6 days for admitted patients. There were no documented cases of infection-related mortality among this pediatric cohort, although 11 patients experienced post-infectious complications that primarily manifested as a loss of taste and smell. Conclusion: These findings suggest that pediatric COVID-19 patients tend to experience mild forms of the disease, without any significant differences in disease severity as a function of patient gender or immune status.

Ischemic stroke revealing COVID-19 infection: Case report.

INTRODUCTION: SARS-COV-2 viral infection primarily targets the respiratory system with a clinical picture that varies from simple symptoms to respiratory distress syndrome requiring hospitalization in the intensive care unit; SARS-CoV-2 also has neuro-invasive capabilities and could spread from the respiratory system to the central nervous system. Recently, some patients with COVID-19 have been shown to have neurological symptoms such as headache, anosmia, dysgeusia, dizziness, impaired consciousness, and ischemic stroke. CASE PRESENTATION: we describe a case of ischemic stroke as the main presentation of COVID-19 in a 68 years old man with no previous history, without any associated respiratory signs; clinical examination revealed left hemiparesis with dysarthria and left facial paralysis, NIHSS score was at 11, the brain CT scan performed 1h30min later, completed by a brain MRI that came back in favor of right frontal, temporal and parietal ischemic stroke. The decision of thrombolysis was indicated in urgency, and the patient benefited from thrombolysis, which proceeded without incidents; the outcome was favorable with regression of symptoms.Ischemic stroke has been widely described among the thromboembolic complications of COVID-19, but only a few papers have reported it as a primary manifestation of COVID-19. CONCLUSION: SARS-COV 2 infection can spread from the respiratory system to the central nervous system, resulting in an inflammatory response and excessive secretion of inflammatory markers, leading to ischemic stroke.

Impact of the COVID-19 pandemic on prevalence and features of tobacco, alcohol and illicat drugs use based on results of international and domestic studies

order to study interrelations between the COVID-19 pandemic and substance use, international and Russian publications about substance users’ risks of being infected with SARS-CoV-2, the course of COVID-19 and possible complications are reviewed. Result of analysis of factors that influence the course of the 2019 coronavirus infection are provided: history of smoking, alcohol abuse, use of illicit drugs, including groups of drugs. The impact of social distancing and lockdown measures on addictive behavior of individuals is also considered. In conclusion, the need for educational and preventive activities aimed at minimizing the influence of psychoactive substance-related risk factors is substantiated. © 2021, V. Serbsky National Medical Research Centre for Psychiatry and Narcology. All rights reserved.

Assessment of FVIII, D-dimer, S. ferritin, and lactate dehydrogenase in hospitalized patients with 2019 coronavirus disease

BACKGROUND: Corona virus disease 2019 (COVID-19) is a coronavirus that can produce a variety of symptoms, ranging from asymptomatic carrier status to severe respiratory failure, multiple organ dysfunction, and death, it might be associated with hypercoagulability as increase in coagulation factor 8 (FVIII). OBJECTIVES: This study was carried out to investigate markers of hypercoaguablility (factor VIII activity, D-Dimer) in hospitalized adult patients with COVID-19, evaluation of certain markers of inflammation (S. ferritin, lactate dehydrogenase [LDH], C-reactive protein [CRP], and erythrocyte sedimentation rate [ESR]) and correlate those markers with each other. PATIENTS AND METHODS: This cross-sectional study included 70 adult hospitalized patients with COVID-19. Blood samples were obtained for FVIII, D. dimer, and ESR. Statistical analysis was performed using Statistical Package for Social Sciences (SPSS) version 23 and Microsoft Office Excel 2010. RESULTS: The mean age of enrolled 70 patients was 60.22 +/- 14.43 years. 44 (62.9%) of patients had neutrophilia and lymphopenia was seen in 41 (58.6%). High ratio of N/L was seen in 66 (94.3%). Low count of eosinophil was seen in 44 (62.9%), high LDH level was seen at 57 (81.4%). Regarding serum ferritin, high level was seen 64 (91.4%) and high level of CRP was seen in 56 (80%). High level of ESR was seen in 64 (91.4%) and high level of D. dimer was seen in 55 (78.6%), while the high level of FVIII was seen in 30 (42.9%) and low FVIII level was seen in 4 (5.7%). CONCLUSIONS: The majority of patients had neutrophilia, lymphopenia, high N/L ratio, and eosinopenia. Markers of inflammation (S. ferritin, LDH, CRP, and ESR), which were elevated. FVIII level and D. dimer were elevated in the majority of patients with COVID-19. Few of the patients were had a low level of FVIII, which might be related to abnormal function of the liver or might be attributed to autoantibodies directed against FVIII.

A Conceptual Model for Virtual Queuing System to Support Social Distancing

In the early December 2019, Coronavirus Disease 2019 (COVID-19) epidemic outbreak emerged from Wuhan City, Hubei Province, China and spread rapidly to the rest of the world. Globally, IT Professionals were forced to adapt and innovate rapidly in response to the pandemic and have devised a variety of IT solutions to ease peoples' transitions into the new normal. There are 4 major categories of IT-based COVID-19 solutions, namely contact tracing, quarantine management, symptom monitoring and information provision. However, most of these applications only focus on contact tracing as opposed to preventing the spread of the virus through the enforcement of social distancing. This paper presents a conceptual model for virtual queuing system, MyQueue which allows its users to enter virtual queues by scanning unique QR codes of various premises. It introduces proper process flows and approaches to eliminate waiting in a crowded queue and help support social distancing efforts to reduce the spread of COVID-19. © 2021 IEEE.

Short-term Cardiovascular Complications of Multi-system Inflammatory Syndrome in Children (MIS-C) in Adolescents and Children.

PURPOSE OF REVIEW: We provide the readers with a review of cardiac complications in children with multi-system inflammatory syndrome in children (MIS-C) and its short-term outcomes. RECENT FINDINGS: Recent reports described the acute cardiac manifestations of MIS-C in children and provided a glimpse of the short-term outcomes. SUMMARY: Children with MIS-C have been reported to acutely have variable degrees of cardiac findings including abnormal cardiac enzymes, abnormal electrocardiographs, decreased systolic function, coronary artery abnormalities from coronary dilation to giant aneurysms, mitral valve regurgitation, tricuspid valve regurgitation, aortic valve insufficiency, pericardial effusion, diastolic dysfunction, abnormal cardiac strain, and abnormal cardiac MRI. The majority of these abnormalities resolved during short-term follow-up. Further studies are needed to assess if transient or persistent cardiac complications are associated with long-term adverse cardiac events in children with MIS-C. SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1007/s40124-021-00258-5.

Impact of Teledermatology on Skin Cancer Patients During COVID-19

Background: during the COVID-19 pandemic, there was difficulty in accessing dermatology consultations, making it impossible to prioritize skin cancer cases. A teledermatology system was designed and implemented, through mobile telephony, for the study of patients with this pathology. Objective: to evaluate the impact of the teledermatology system for the study of skin cancer in patients treated at the Guillermo Fernandez Hernandez-Baquero Dermatological Hospital during the COVID-19 pandemic. Methods: a descriptive study was carried out to evaluate the impact of teledermatology in 88 patients with lesions suspected of skin cancers, referred from Primary Care and treated at the Guillermo Fernandez Hernandez-Baquero Dermatological Hospital in the period since April 1 2020 until April 1, 2021. A teledermatology system was designed, of the teleconsultation type with the possibility of remote diagnosis, based on the exchange of images and texts, on an Android mobile device. The descriptive statistical method was used. The results were expressed in tables for better understanding. Results: basal cell carcinoma predominated in 63.6 %. The clinic pathological correlation for basal cell carcinoma was 96.4 %, by teledermatology and by face-to-face consultation, respectively. Simple agreement was 93.2 %. Disagreements were slight for 6.8 %. The level of satisfaction was 95.5 %, very satisfied with the applied teledermatology system. Conclusions: the teledermatology system has technical feasibility, is efficient, useful, with diagnostic accuracy, reliability and reproducibility, being effective in the diagnosis of skin cancer, in unfavorable epidemiological conditions such as the COVID-19 pandemic.

Environmental sampling of the severe acute respiratory syndrome coronavirus 2 Delta variant in the inpatient wards of a hospital in Nanjing.

BACKGROUND: Little is known about severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) Delta variant of concern (VOC)-contaminated environmental surfaces and air in hospital wards admitting COVID-19 cases. Our study was designed to identify high-risk areas of Delta VOC contamination in the hospital and provide suggestions to in-hospital infection control. We analyzed the SARS-CoV-2 Delta VOC contamination in the air and environmental surface samples collected from a hospital in Nanjing, China. METHODS: We collected data on clinical features, laboratory tests, swab tests, and hospital wards, identified the factors associated with environmental contamination, and analyzed patients' hygiene behaviors during hospitalization. RESULTS: A total of 283 environmental surface and air samples were collected from a hospital admitting 36 COVID-19 patients. Twelve swab samples from ten patients were positive. Toilet seats had the highest contamination rate (11.8%), followed by bedside tables (8.2%), garbage bins (5.9%), and bedrails (1.6%). The median time of symptom onset to surface sampling was shorter in the positive environment group than in the negative environment group (11 vs. 18 days; P=0.001). The results indicated that environmental surface contamination was associated with positive anal swabs [odds ratio (OR) 27.183; 95% CI: 2.359-226.063; P=0.003] and the time from symptom onset to surface sampling (OR 0.801; 95% CI: 0.501-0.990; P=0.046). The survey revealed that 33.3% of the patients never cleaned or disinfected their bedside tables or toilets, and 8.3% of them only cleaned their bedside tables or toilets. More than half of the patients often (25%) or always (30.6%) put the used masks on their bedside tables. Only 16.7% of the patients threw the masks into the specific garbage bin for used masks. CONCLUSIONS: The SARS-CoV-2 Delta VOC was detected on environmental surfaces, especially toilet seats and bedside tables, within a median time of 11 days after symptom onset. Our study provided potential predictors for environmental surface contamination, including positive anal swabs and the time from symptom onset to sampling. Disinfecting high-risk environmental surfaces should be emphasized in hospital wards, especially for patients in the early stage of COVID-19.

Oral Healthcare Management of Children after COVID-19 Outbreak.

The emergence of the novel 2019 coronavirus disease (COVID-19) pandemic has led to a significant challenge to healthcare professionals. Among all the healthcare providers, dental clinical setup is exposed to the generation of potentially hazardous aerosols which could be a point of cross-contamination. Dentists catering to pediatric patients need to take special precautions, as they have milder symptoms or could be asymptomatic and hence potential vectors for the transfer of infection. One needs to change the perspective to manage the oral health of children as a child's oral health presents specific problems that could be time-bound and hence need to be treated accordingly. These problems can be managed on one hand by preventive methods, and on the other by implementing specific protocols relating to the conditions that represent an emergency, or those situations that fall into the category of elective dental procedures. This article highlights the routes of transmission in a dental practice and focuses on the categorization of treatment for children based on treatment needs. It proposes a restructuring of the treatment protocol and hence shifting to minimal invasive or non-aerosol-generating procedures (AGP). These techniques are also proposed to be used even after the end of the current emergency period to minimize the aerosol splatter. CLINICAL SIGNIFICANCE: The article highlights the protocol that needs to be followed after treatment categorization during and after COVID-19 pandemic. HOW TO CITE THIS ARTICLE: Lamba G, Nagpal DI, Chowdhari P, et al. Oral Healthcare Management of Children after COVID-19 Outbreak. Int J Clin Pediatr Dent 2021;14(2):293-297.

Cardiac echocardiogram findings of severe acute respiratory syndrome coronavirus-2-associated multi-system inflammatory syndrome in children.

BACKGROUND: A novel paediatric disease, multi-system inflammatory syndrome in children, has emerged during the 2019 coronavirus disease pandemic. OBJECTIVES: To describe the short-term evolution of cardiac complications and associated risk factors in patients with multi-system inflammatory syndrome in children. METHODS: Retrospective single-centre study of confirmed multi-system inflammatory syndrome in children treated from 29 March, 2020 to 1 September, 2020. Cardiac complications during the acute phase were defined as decreased systolic function, coronary artery abnormalities, pericardial effusion, or mitral and/or tricuspid valve regurgitation. Patients with or without cardiac complications were compared with chi-square, Fisher's exact, and Wilcoxon rank sum. RESULTS: Thirty-nine children with median (interquartile range) age 7.8 (3.6-12.7) years were included. Nineteen (49%) patients developed cardiac complications including systolic dysfunction (33%), valvular regurgitation (31%), coronary artery abnormalities (18%), and pericardial effusion (5%). At the time of the most recent follow-up, at a median (interquartile range) of 49 (26-61) days, cardiac complications resolved in 16/19 (84%) patients. Two patients had persistent mild systolic dysfunction and one patient had persistent coronary artery abnormality. Children with cardiac complications were more likely to have higher N-terminal B-type natriuretic peptide (p = 0.01), higher white blood cell count (p = 0.01), higher neutrophil count (p = 0.02), severe lymphopenia (p = 0.05), use of milrinone (p = 0.03), and intensive care requirement (p = 0.04). CONCLUSION: Patients with multi-system inflammatory syndrome in children had a high rate of cardiac complications in the acute phase, with associated inflammatory markers. Although cardiac complications resolved in 84% of patients, further long-term studies are needed to assess if the cardiac abnormalities (transient or persistent) are associated with major cardiac events.

Supplementary research on K150del variant of activated protein C.

Activated protein C (APC) is an anticoagulant with potent cytoprotective and anti-inflammatory effects. K150del, a natural variant of APC, is associated with reduced anticoagulant activity. We performed a comprehensive study to analyze the functional alterations of the K150del mutant. Transcriptome analysis of HEK 293T cells treated with wild and mutant APC revealed differentially expressed genes enriched in inflammatory, apoptotic, and virus defense-related signaling pathways. Both wild and mutant APC displayed concentration-dependent cytoprotective effects. Low concentrations of K150del mutant resulted in decreased anti-inflammatory and anti-apoptotic activities, whereas its higher concentrations restored these effects. Expression of virus defense-related genes improved in mouse lung tissues after repeated administration of the APC variant. These results suggest that the APC K150del mutant could help clinicians to accurately predict disease risks and serve as a potential auxiliary therapeutic in viral infections, including 2019 coronavirus disease (COVID-19).

Hematologic changes predict clinical outcome in recovered patients with COVID-19.

2019 coronavirus disease (COVID-19) presents as a newly recognized pneumonia that has brought about a global pandemic and is increasingly considered as a systemic illness. We investigated the clinical and laboratory features of recovered COVID-19 patients without pre-existing hematologic diseases at Wuhan No. 1 Hospital. Fifty-nine male and 68 female Chinese patients were included with the median age at 64 years in the present study. Eosinopenia (37.80%), monocytosis (51.97%), lymphocytopenia (25.20%), and anemia (51.97%) were the most common hematologic findings in our cohort, particularly in severe or critically ill COVID-19. The levels of changes in leukocytes, neutrophils, lymphocytes, monocytes, eosinophils, basophils, platelets, hemoglobin levels, mean corpuscular volume (MCV), and mean cell hemoglobin concentration (MCHC) are overall associated with lung involvement, oxygen demand, and disease activity. However, changes of eosinophils (end hospitalization-baseline) (coefficients = 10.32; 95% CI = 1.03-19.60, P = 0.03) and basophils (Max - Min) (coefficients = 71.43; 95% CI = 8.55-134.31, P = 0.03) were independent predictors of delayed recovery in the hospital by the multivariate analysis in this recovered population. A variety of hematologic changes are associated with the severity and clinical outcome of recovered COVID-19 patients, which warrants further exploration of their underlying mechanisms.

COVID-19-Related Misinformation among Parents of Patients with Pediatric Cancer.

We conducted a survey among 735 parents to determine differences in endorsement of misinformation related to the coronavirus disease pandemic between parents of children in cancer treatment and those with children who had no cancer history. Parents of children with cancer were more likely to believe misinformation than parents of children without cancer.

The impact of ABO blood group on COVID-19 infection risk and mortality: A systematic review and meta-analysis.

The 2019 coronavirus disease (COVID-19) has become a global pandemic. Several studies report that ABO blood group polymorphism may be related to COVID-19 susceptibility and clinical outcomes; however, the results are controversial. We conducted a systematic review and meta-analysis to investigate whether ABO blood groups are associated with increased COVID-19 morbidity and mortality. A total of 715 articles were retrieved from seven databases. Ten articles were selected for meta-analysis after removal of duplicates and two levels of screenings. Overall, individuals with blood group A [odds ratio (OR) = 1.33, 95% confidence interval (CI) 1.14 to 1.56] and B (OR = 1.06, 95% CI 1.00 to 1.13) had a substantially higher risk of COVID-19, whereas this was not the case for blood group AB (OR = 1.07, 95% CI 0.88 to 1.30). Individuals with blood group O was not prone to develop the disease (OR = 0.71, 95% CI 0.60 to 0.84). Moreover, the risk of COVID-19 was significantly associated with the Rh-positive blood group (OR = 1.22, 95% CI 0.99 to 1.50). A meta-analysis of 5 studies suggested that blood group A was associated with a significantly increased risk of COVID-19 mortality (OR = 1.25, 95% CI 1.02 to 1.52). Mild publication bias was found in the included studies. This systematic review and meta-analysis indicated that blood groups A and B may be risk factors for COVID-19, whereas the blood group O appears to be protective. Blood group A may be related to unfavourable outcomes. Further rigorous and high-quality research evidence is needed to confirm this association.