SARS-CoV2 infection induce miR-155 expression and skewed Th17/Treg balance by changing SOCS1 level: A clinical study.

BACKGROUND: One of the regulators in severe acute respiratory syndrome coronavirus2 (SARS-CoV2) infection is miRNAs. In COVID-19 patients, immunological responses to SARS-CoV2 infection may be impacted by miR-155, a miRNA associated to inflammation. MATERIALS AND METHODS: Peripheral blood mononuclear cells (PBMCs) of 50 confirmed COVID-19 patients /Healthy Controls (HCs) was isolated by Ficoll. The frequency of T helper 17 and regulatory T cells was analyzed by flowcytometry. The RNA was extracted from each sample and after synthesis of c-DNA, the relative expression of miR-155, suppressor of cytokine signaling (SOCS-1), Signal transducer and activator of transcription 3(STAT3), and Fork Head Box Protein 3 (FoxP3) was evaluated by real-time PCR. The protein level of STAT3, FoxP3 and RORγT in the isolated PBMCs measured by western blotting. The serum level of IL-10, TGF-ß, IL-17 and IL21 was assessed by ELISA method. RESULTS: The population of Th17 cells showed a significant rise, whereas Treg cells reduced in COVID-19 cases. The master transcription factor of Treg (FoxP3) and Th17 (RORγT) relative expression showed the same pattern as flowcytometry. STAT3 level of expression at RNA and protein level increased in COVID-19 cases. FOXP3 and SOCS-1 proteins were down-regulated. The relative expression of miR-155, up-regulated in PBMC of COVID-19 patients and revealed a negative correlation with SOCS-1. The serum cytokine profile showed a reduction in TGF-ß, on the other hand an increase was seen in IL-17, IL-21 and IL-10 in COVID-19 cases toward control group. CONCLUSION: Based on the studies conducted in this field, it can be suggested that Th17/Treg in covid-19 patients can be affected by miR-155 and it can be considered a valuable diagnostic and prognostic factor in this disease.

Years of life lost (YLL) associated with COVID-19 deaths in Khorasan-RAZAVI province, Iran.

BACKGROUND: The number of deaths among people with coronavirus disease 2019 (COVID-19) does not show the true impact of the disease on communities. Therefore, this study aimed to calculate years of life lost (YLL) due to premature death in patients with COVID-19. METHODS: We performed a descriptive cross-sectional study based on data from one of the largest provinces of Iran, in the period 13 February 2020 to 17 May 2021. We used WHO proposed guidelines for the calculation of the burden of diseases to calculate the YLL among patients with COVID-19, taking into consideration gender in different age groups. RESULTS: Findings showed that 13 628 deaths were due to COVID-19 with associated 249 309 YLL. The study reported higher mortality among men (1222 cases) in the age group over 85 years than in women (840) of the same age group. The minimum number of YLL for men was 1749 in the 5-9 years age group and that for women was 1551 years in the 14-10 years age group. CONCLUSION: The high number of deaths due to COVID-19 has led to high YLL due to premature death. The provision of adequate health care and appropriate policies will bring about a decrease in YLL due to COVID-19.

Effect of the Previous History of the SARS-CoV-2 Infections on Antibody Levels among Sputnik V Vaccinated Healthcare Workers.

Background: Measuring the level of antibodies produced post-vaccination in response to the SARS-CoV-2 spike protein is considered a strategy for estimating the effectiveness of the COVID-19 vaccines. Objective: To examine the antibody levels among the healthcare workers in different hospitals in Mashhad, Iran after receiving the second dose of Sputnik V. Methods: In this study, we enrolled 230 healthcare workers for evaluating the Gam-COVID-Vac or Sputnik V after the second administration in different hospitals in Mashhad. Antibody levels of spike protein were quantitatively evaluated in a sample of 230 negative RT-PCR tests for the COVID-19 individuals. The analysis has been done based on an immunological assay using enzyme-linked immunosorbent assay (ELISA). The infection history of the subjects and their families was examined through their medical records. Results: Our results demonstrated a significant association between a higher titer of IgG and a previous history of the COVID-19 infection (P<0.001). Moreover, the chance of detecting antibodies titer more than 50 AU/ml was 16.99 in these people which was significantly higher than in people without a history of infection pre-vaccination [%95CI: (7.38,39.12), P<0.001]. Conclusion: This result demonstrates that the efficacy of antibody production is related to the previous history of the SARS-CoV-2 infections. Ongoing monitoring of the level of antibody among vaccinated populations will help evaluating the effect of vaccines on humoral immunity status.

Potent SARS-CoV2-specific T-cell response in asymptomatic hemodialysis patients with hidden COVID-19 infection history.

BACKGROUND: COVID-19-related immune responses in patients with end-stage renal disease (ESRD) are characterized in detail by the humoral response, but their cellular immunity has not been clarified. Here, we evaluated virus-specific T cells in parallel with serology-related tests. METHODS: In this study, 104 ESRD patients at the hemodialysis ward of Imam Reza hospital at Tabriz (Iran) were enrolled. After blood sampling, SARS-CoV2-specific humoral and cellular immune responses were evaluated by SARS-CoV2-specific IgM/IgG ELISA and peptide/MHCI-Tetramers flow cytometry, respectively. RESULTS: Our results showed that 14 (13.5%) and 45 (43.3%) patients had specific SARS-CoV2 IgM and IgG in their sera, respectively. Immunophenotyping for SARS-CoV2-specific CD8+ T lymphocytes revealed that 68 (65.4%) patients had these types of cells. Among SARS-CoV2-specific CD8+ T lymphocytes positive subjects, 13 and 43 individuals had positive results for specific SARS-CoV2 IgM and IgG existence, respectively. Also, there was a relationship between specific SARS-CoV2 IgM (p = 0.031) and IgG (p < 0.0001) existence and having SARS-CoV2-specific TCD8+ lymphocytes in the studied population. CONCLUSION: Despite not having clinical symptoms, a high rate of SARS-CoV2-specific T-cell response in asymptomatic ESRD patients may reveal a high burden of asymptomatic COVID-19 infection in these patients.

Genetic diversity of Mycobacterium tuberculosis isolates from northwest of Iran during COVID-19 era

BackgroundTuberculosis (TB) is considered one of the most infectious diseases in the world. In this study, we intended to examine the epidemiology of tuberculosis by MIRU-VNTR to define the changes that occur in the transmission of tuberculosis in the region during the COVID-19 era. A total of 120 Mycobacterium tuberculosis isolates were collected from sputum samples of patients referred to East Azerbaijan Center TB from December 2020 to August 2021. Demographic information such as age, sex, place of birth, previous TB history, and relevant medical data was collected. The proportion method was performed for drug susceptibility testing, and the PCR-based MIRU-VNTR method was applied to identify molecular epidemiology relationships.ResultsThe isolates were collected from 78 male (65%) and 39 female (32.5%) Iranian patients and 3 (2.5%) Azerbaijani patients. Ninety-three distinct patterns were identified including 15 clustered patterns and 36 unique patterns. The largest cluster was composed of seven isolates. Furthermore, one cluster with 5 members, four clusters with 3 members, and nine clusters with 2 members. In MIRU-VNTR typing, 75 clusters belonged to the Tabriz region and just 3 to the Republic of Azerbaijan. All isolates were sensitive to rifampin, isoniazid, and ethambutol.ConclusionsResults of the current study showed COVID-19 pandemic had a direct effect on the transmission and diagnosis of tuberculosis. Less diagnosis and less clustering can indicate public controls and hygiene, and the use of masks had a direct effect on the transmission and diagnosis of tuberculosis. However, misidentification and less focus on other respiratory infections are expected during the pandemic. Studies on the co-infection of COVID-19 and tuberculosis and the role of mask and sanitization against TB are strongly recommended.

Immunomodulatory role of Nanocurcumin in COVID-19 patients with dropped natural killer cells frequency and function.

The ongoing COVID-19 pandemic is still a challenging problem in the case of infection treatment. The immunomodulatory effect of Nanocurcumin was investigated in the present study in an attempt to counterbalance the immune response and improve the patients' clinical symptoms. 60 confirmed COVID-19 patients and 60 healthy controls enrolled in the study. COVID-19 patients were divided into Nanocurcumin and placebo received groups. Due to the importance of the role of NK cells in this disease, the frequency, cytotoxicity, receptor gene expression of NK cells, and serum secretion levels of inflammatory cytokines IL-1ß, IL-6, TNF-α, as well as circulating C5a as a chemotactic factor an inflammatory mediator was evaluated by flow cytometry, real-time PCR and enzyme-linked immunosorbent assay in both experimental groups before and after the intervention. Given the role of measured factors in the progression and pathogenesis of COVID-19 disease, the results can help find appropriate treatments. The results of this study indicated that the Nanocurcumin could significantly increase the frequency and function of NK cells compared to the placebo-treated group. As an immunomodulatory agent, Nanocurcumin may be a helpful choice to improve NK cell function in COVID-19 patients and improve the clinical outcome of patients.

Immune system-related soluble mediators and COVID-19: basic mechanisms and clinical perspectives.

During SARS-CoV-2 infection, an effective immune response provides the first line of defense; however, excessive inflammatory innate immunity and impaired adaptive immunity may harm tissues. Soluble immune mediators are involved in the dynamic interaction of ligands with membrane-bound receptors to maintain and restore health after pathological events. In some cases, the dysregulation of their expression can lead to disease pathology. In this literature review, we described current knowledge of the basic features of soluble immune mediators and their dysregulation during SARS-CoV-2 infections and highlighted their contribution to disease severity and mortality. Video Abstract.

SARS-CoV-2 vaccines: A double-edged sword throughout rapid evolution of COVID-19.

After more than 2 years of the coronavirus disease 2019 pandemic caused by severe acute respiratory syndrome coronavirus 2, several questions have remained unanswered that affected our daily lives. Although substantial vaccine development could resist this challenge, emerging new variants in different countries could be considered as potent concerns regarding the adverse effects of reinfection or postvaccination. Precisely, these concerns address some significant and probable outcomes in vaccinated or reinfected models, followed by some virus challenges, such as antibody-dependent enhancement and cytokine storm. Therefore, the importance of evaluating the effectiveness of neutralizing antibodies (nAbs) elicited by vaccination and the rise of new variants must be addressed.

A comprehensive evaluation of the immune system response and type-I Interferon signaling pathway in hospitalized COVID-19 patients.

BACKGROUND: The COVID-19 pandemic has become the world's main life-threatening challenge in the third decade of the twenty-first century. Numerous studies have been conducted on SARS-CoV2 virus structure and pathogenesis to find reliable treatments and vaccines. The present study aimed to evaluate the immune-phenotype and IFN-I signaling pathways of COVID-19 patients with mild and severe conditions. MATERIAL AND METHODS: A total of 100 COVID-19 patients (50 with mild and 50 with severe conditions) were enrolled in this study. The frequency of CD4 + T, CD8 + T, Th17, Treg, and B lymphocytes beside NK cells was evaluated using flow cytometry. IFN-I downstream signaling molecules, including JAK-1, TYK-2, STAT-1, and STAT-2, and Interferon regulatory factors (IRF) 3 and 7 expressions at RNA and protein status were investigated using real-time PCR and western blotting techniques, respectively. Immune levels of cytokines (e.g., IL-1ß, IL-6, IL-17, TNF-α, IL-2R, IL-10, IFN-α, and IFN-ß) and the existence of anti-IFN-α autoantibodies were evaluated via enzyme-linked immunosorbent assay (ELISA). RESULTS: Immune-phenotyping results showed a significant decrease in the absolute count of NK cells, CD4 + T, CD8 + T, and B lymphocytes in COVID-19 patients. The frequency of Th17 and Treg cells showed a remarkable increase and decrease, respectively. All signaling molecules of the IFN-I downstream pathway and IRFs (i.e., JAK-1, TYK-2, STAT-1, STAT-2, IRF-3, and IRF-7) showed very reduced expression levels in COVID-19 patients with the severe condition compared to healthy individuals at both RNA and protein levels. Of 50 patients with severe conditions, 14 had anti-IFN-α autoantibodies in sera. Meanwhile, this result was 2 and 0 for patients with mild symptoms and healthy controls, respectively. CONCLUSION: Our results indicate a positive association of the existence of anti-IFN-α autoantibodies and immune cells dysregulation with the severity of illness in COVID-19 patients. However, comprehensive studies are necessary to find out more about this context. Video abstract.

Postbiotics as the key mediators of the gut microbiota-host interactions.

The priority of the Sustainable Development Goals for 2022 is to reduce all causes related to mortality. In this regard, microbial bioactive compounds with characteristics such as optimal compatibility and close interaction with the host immune system are considered a novel therapeutic approach. The fermentation process is one of the most well-known pathways involved in the natural synthesis of a diverse range of postbiotics. However, some postbiotics are a type of probiotic response behavior to environmental stimuli that usually play well-known biological roles. Also, postbiotics with unique structure and function are key mediators between intestinal microbiota and host cellular processes/metabolic pathways that play a significant role in maintaining homeostasis. By further understanding the nature of parent microbial cells, factors affecting their metabolic pathways, and the development of compatible extraction and identification methods, it is possible to achieve certain formulations of postbiotics with special efficiencies, which in turn will significantly improve the performance of health systems (especially in developing countries) toward a wide range of acute/chronic diseases. The present review aims to describe the fundamental role of postbiotics as the key mediators of the microbiota-host interactions. Besides, it presents the available current evidence regarding the interaction between postbiotics and host cells through potential cell receptors, stimulation/improvement of immune system function, and the enhancement of the composition and function of the human microbiome.

Genetic diversity of Mycobacterium tuberculosis isolates from northwest of Iran during Covid-19 era

Tuberculosis (TB) is considered one of the most infectious diseases in the world. In this study, we intended to examine the epidemiology of tuberculosis by MIRU-VNTR to define the changes that occur in the transmission of tuberculosis in the region during the COVID-19 era. A total of 120 Mycobacterium tuberculosis isolates were collected from sputum samples of patients referred to East Azerbaijan Center TB from December 2020 to August 2021. Demographic information such as age, sex, place of birth, previous TB history, and relevant medical data was collected. The drug susceptibility testing was performed by the proportion method and the PCR-based MIRU-VNTR method was applied to identify molecular epidemiology relationships. The isolates were collected from 78 males (52%) and 72 females (48%) Iranian patients and 6 (4%) Azerbaijani patients. 120 distinct patterns were identified including 15 clustered patterns and 36 unique patterns. The largest cluster was composed of seven isolates. Furthermore,1 cluster with 7 isolates, 1 cluster with 5 members, 4 clusters with 3 members, and 9 clusters with 2 members. In MIRU-VNTR typing, 75 clusters belonged to Tabriz and just 3 clusters belonged to Azerbaijan. All isolates were sensitive to rifampin, isoniazid and ethambutol. Results of the current study showed COVID-19 pandemic had a direct effect on the transmission and diagnosis of tuberculosis. Less diagnosis and less clustering can indicate public controls and hygiene and the use of masks had a direct effect on the transmission and diagnosis of tuberculosis. However, misidentification and less focus on other respiratory infections are expected during the pandemic. Studies on co-infection of COVID-19 and tuberculosis and the role of mask and sanitization against TB are strongly recommended.

The Experiences of Nurses of Infectious and Non- Infectious Wards of Caring COVID-19 Patients in a Big Hospital in Iran: A Qualitative Study.

Background: Nurses play a very important role in caring for patients with coronavirus disease-19 (COVID-19). They are on the frontline fighting COVID-19. The objective was to explore the experiences of nurses in the surgical and infectious wards about caring for patients with COVID-19 in a large and tertiary care hospital in Iran. Materials and Methods: This was a qualitative study. Semi-structured qualitative interviews were conducted with 18 nurses in the Imam Reza Hospital Complex from April to May 2020, Mashhad, Iran. Data analysis was performed using the method proposed by Lundman and Granheim. The Maxqda10 software was used. Results: The experiences were summarized into three categories: (1) experiencing new feelings and relationships with colleagues and patients, (2) viewpoints about managers' performance, and (3) concern about getting infected with COVID-19. Findings reflected similar experiences on personal protective equipment between nurses in the surgical and infectious wards. Experiencing new feelings and relationships with colleagues and patients and concern about getting infected and spreading the COVID-19 were mostly expressed by infectious nurses and surgical nurses, respectively. Conclusions: This research results provide evidence of the experiences of infectious and non-infectious disease nurses who are currently caring for COVID-19 patients. Due to some differences between the experiences of these two groups in COVID-19, it is suggested to pay more attention to the needs and required skills in the staff mix during a crisis.

Serum levels of vitamin D and immune system function in patients with COVID-19 admitted to intensive care unit.

OBJECTIVE: Vitamin D is believed to affect the functionality of the immune system for the prevention of coronavirus disease. To investigate the role of this vitamin against the Coronavirus, this study analyzed the serum levels of vitamin D, the transcription pattern of inflammatory cytokines, and the frequency of total lymphocytes, TCD4+, TCD8+, and NK cells in 50 COVID-19-affected subjects in comparison to 50 healthy participants. MATERIALS AND METHODS: This study diagnosed and evaluated 100 patients. Frequency of lymphocytes was determined using flow cytometry. Cytokine expression levels were measured using Real-Time PCR. Serum levels of vitamin D and cytokines levels in cultured cell supernatant were measured by ELISA. RESULTS: Patients with COVID-19 exhibited decreased serum levels of vitamin D versus the healthy participants (p = 0.0024). The total number of lymphocytes, TCD4+, TCD8+, and NK cells was significantly reduced in patients with COVID-19 (p < 0.0001). Considerable upregulation of IL-12, IFN-γ, and TNF-α was seen in COVID-19 patients compared to the control group, whereas IFN-α was downregulated in COVID-19 patients. ELISA results also had increased levels of IL-12, TNF-α, and IFN-γ (p = 0.0014, 0.0012, and p < 0.0001, respectively), and decreased level of IFN-α (p = 0.0021) in patients with COVID-19 compared to the control group. CONCLUSION: These findings suggest a probable association among vitamin D concentrations, immune system function, and risk of COVID-19 infection. As a result, it is recommended that vitamin D be considered as a candidate for handling and controlling COVID-19 because of its ability to target the cytokine storm and its antiviral effects.

Development, Implementation, and User Evaluation of COVID-19 Dashboard in a Third-Level Hospital in Iran.

INTRODUCTION: The implementation of a dashboard enables managers to make informed and evidence-based decisions through data visualization and graphical presentation of information. This study aimed to design and implement a COVID-19 management dashboard in a third-level hospital in Mashhad, Iran. MATERIALS AND METHODS: This descriptive developmental applied study was conducted in the second half of 2020 in three stages, using user-centered design methodology in four phases: (1) specification of the application context, (2) specification of requirements, (3) creation of design solutions, and (4) evaluation of designs. Data collection in each phase was performed through holding group discussions with the main users, nominal group techniques, interviews, and questioners. The dashboard prototype for the data display was designed using the Power BI Desktop software. Subsequently, users' comments were obtained using the focus group method and included in the dashboard. RESULTS: In total, 25 indicators related to input, process, and output areas were identified based on the findings of the first stage. Moreover, eight items were introduced by participants as dashboard requirements. The dashboard was developed based on users' feedback and suggestions, such as the use of colors, reception of periodic and specific reports based on key performance indicators, and rearrangement of the components visible on the page. The result of the user satisfaction survey indicated their satisfaction with the developed dashboard. CONCLUSION: The selection of proper criteria for the implementation of an effective dashboard is critical for the health care organization since they are designed with a high-tech and content-based environment. The dashboard in the present study was a successful combination of clinical and managerial indicators. Future studies should focus on the design and development of dashboards, as well as benchmarking by using data from several hospitals.

Immune response variables and viral mutations impact on COVID-19 reinfection and relapse.

The possibility of human reinfection with SARS-CoV-2, the coronavirus responsible for COVID-19, has not previously been thoroughly investigated. Although it is generally believed that virus-specific antibodies protect against COVID-19 pathogenesis, their duration of function and temporal activity remain unknown. Contrary to media reports that people retain protective antibody responses for a few months, science does not exclude reinfection and disease relapse shortly after initiating all immune responses during the primary onset of COVID-19. Despite production of antiviral antibodies, activated CD4+/CD8+ lymphocytes, and long-lived memory B cells, susceptibility to reinfection in humans for extended periods cannot be precluded due to repeated exposures to coronavirus or potential reactivation of the virus due to incomplete virus clearance. However, the mechanism of reinfection remains unknown. The biological characteristics of SARS-CoV-2, such as emergence of multiple mutations in the virus RNA molecules, transmissibility, rates of infection, reactivation and reinfection, can all affect the trajectory of the virus spread. Innate and adaptive immune response variables, differences in underlying diseases, and comorbidities, particularly in high risk individuals, can influence the dynamics of the virus infection. In this article, immune parameters and viral mutations pertaining to reinfection and disease relapse are reviewed and scientific gaps are discussed.

SARS-CoV-2 (Covid-19) vaccines structure, mechanisms and effectiveness: A review.

The world has been suffering from COVID-19 disease for more than a year, and it still has a high mortality rate. In addition to the need to minimize transmission of the virus through non-pharmacological measures such as the use of masks and social distance, many efforts are being made to develop a variety of vaccines to prevent the disease worldwide. So far, several vaccines have reached the final stages of safety and efficacy in various phases of clinical trials, and some, such as Moderna/NIAID and BioNTech/Pfizer, have reported very high safety and protection. The important point is that comparing different vaccines is not easy because there is no set standard for measuring neutralization. In this study, we have reviewed the common platforms of COVID-19 vaccines and tried to present the latest reports on the effectiveness of these vaccines.

Reduction and exhausted features of T lymphocytes under serological changes, and prognostic factors in COVID-19 progression.

AIMS: Coronavirus disease 2019 (COVID-19) is a novel viral infection threatening worldwide health as currently there exists no effective treatment strategy and vaccination programs are not publicly available yet. T lymphocytes play an important role in antiviral defenses. However, T cell frequency and functionality may be affected during the disease. MATERIAL AND METHODS: Total blood samples were collected from patients with mild and severe COVID-19, and the total lymphocyte number, as well as CD4+ and CD8 + T cells were assessed using flowcytometry. Besides, the expression of exhausted T cell markers was evaluated. The levels of proinflammatory cytokines were also investigated in the serum of all patients using enzyme-linked immunesorbent assay (ELISA). Finally, the obtained results were analyzed along with laboratory serological reports. RESULTS: COVID-19 patients showed lymphopenia and reduced CD4+ and CD8 + T cells, as well as high percentage of PD-1 expression by T cells, especially in severe cases. Serum secretion of TNF-α, IL-1ß, and IL-2 receptor (IL-2R) were remarkably increased in patients with severe symptoms, as compared with healthy controls. Moreover, high levels of triglyceride (TG) and low density lipoprotein cholesterol (LDL-C), were correlated with the severity of the disease. CONCLUSION: Reduced number and function of T cells were observed in COVID-19 patients, especially in severe patients. Meanwhile, the secretion of proinflammatory cytokines was increased as the disease developed. High level of serum IL-2R was also considered as a sign of lymphopenia. Additionally, hypercholesterolemia and hyperlipidemia could be important prognostic factors in determining the severity of the infection.

The lethal internal face of the coronaviruses: Kidney tropism of the SARS, MERS, and COVID19 viruses.

The kidney is one of the main targets attacked by viruses in patients with a coronavirus infection. Until now, SARS-CoV-2 has been identified as the seventh member of the coronavirus family capable of infecting humans. In the past two decades, humankind has experienced outbreaks triggered by two other extremely infective members of the coronavirus family; the MERS-CoV and the SARS-CoV. According to several investigations, SARS-CoV causes proteinuria and renal impairment or failure. The SARS-CoV was identified in the distal convoluted tubules of the kidney of infected patients. Also, renal dysfunction was observed in numerous cases of MERS-CoV infection. And recently, during the 2019-nCoV pandemic, it was found that the novel coronavirus not only induces acute respiratory distress syndrome (ARDS) but also can induce damages in various organs including the liver, heart, and kidney. The kidney tissue and its cells are targeted massively by the coronaviruses due to the abundant presence of ACE2 and Dpp4 receptors on kidney cells. These receptors are characterized as the main route of coronavirus entry to the victim cells. Renal failure due to massive viral invasion can lead to undesirable complications and enhanced mortality rate, thus more attention should be paid to the pathology of coronaviruses in the kidney. Here, we have provided the most recent knowledge on the coronaviruses (SARS, MERS, and COVID19) pathology and the mechanisms of their impact on the kidney tissue and functions.

SARS-CoV-2: Unique Challenges of the Virus and Vaccines.

In November 2019, the highly infectious coronavirus SARS-CoV-2 emerged in Wuhan, China, and has since spread to almost all countries worldwide. Since its emergence, the COVID-19 infection has led to significant public health, economic and social problems. The current pandemic has inspired researchers to make every effort to design and develop an effective COVID-19 vaccine to provide sufficient protection against the virus and control the infection. In December 2020, the Pfizer vaccine was the first COVID-19 vaccine given Emergency Use Authorization (EUA), and the second FDA so-approved vaccine was the Moderna mRNA-1273 vaccine, which was introduced a week later. Both Pfizer and Moderna vaccines are mRNA-based vaccines, and are estimated to have an efficacy rate of more than 94%. The aim of this article is to provide a review of the attempts made to develop safe SARS-CoV-2 vaccines, highlighting potential challenges and concerns, such as disease enhancement, virus mutations, and public acceptance of the vaccine.