Severe Acute Respiratory Syndrome (SARS), an emerging infectious disease first reported from the Chinese province of Guangdong, has already caused one worldwide outbreak. The syndrome spread across the globe by travelers. The etiologic agent was unknown at the beginning, but because of the rapid spread of the disease, an infectious agent with high transmission potency was suspected. Later workers at the Center for Disease Control and Prevention (CDC) and World Health Organization (WHO) succeeded in isolating a new coronavirus with a distinct genome from SARS patients. This new virus spread all over the world in a few weeks and the epidemic peaked in March and April. Within a short period of time, the epidemic inflicted huge economic losses on the involved countries, especially in Asia. Finally the outbreak was contained in July, 2003. But is this really the end of SARS? the are no easy answers. Considering this new disease and the probability of its reemergence, it is necessary for all health care workers to be familiar with some features of the syndrome (clinical and laboratory findings, approach to patients, routes of transmission; pre and post-travel recommendations and ways to control the infection). We will provide you with some important information about this new emerging disease from a variety of sources.      

Background and Aim: The novel coronavirus 2019 can lead to a vast range of respiratory complications, from mild to severe, driving to acute respiratory distress syndrome (ARDS). Common symptoms of COVID-19 include fever, fatigue, and dry cough, which can lead to complications, such as gastrointestinal disorders, and liver, cardiac, and renal dysfunctions. Alteration in the hematological markers is one of the COVID-19 diseases evaluated by our study. Materials and Methods: In this study, hematological markers, including the levels of ESR, BS, Hb, HCT, MCV, MCH, MCHC, platelet, WBC, RBC, neutrophil, and lymphocyte, have been assessed and compared in both case and control groups. Furthermore, we assessed the associations between hematological parameters, clinical manifestations, and underlying medical conditions. Results: Our data showed that RBC, HCT, and ESR were significantly associated with the novel coronavirus 2019 infection according to the disease progression. ESR (P= 0. 022), Hb (P= 0. 032), and BS (P= 0. 01) levels in male people infected by SARS-CoV-2 proved to have a significant relationship with the control group. Moreover, BS, Hb, HCT, ESR, and neutrophil showed significant variations in diabetic individuals suffering from SARS-CoV-2 infection. Conclusion: The dropping of the hematological markers in COVID-19 is linked with a noticeably increased mortality rate, while high neutrophil and BS levels are related to aggravation of the disease. Monitoring the hematological markers can contribute significantly to selecting the proper treatment and hamper of disease worsening.

The outbreak of severe acute respiratory syndrome (SARS ‐ CoV-2) in December 2019 has led to the epidemic of Covid-19. Recent clinical studies have shown that parts of the nervous system; Cerebrospinal fluid (CSF) are involved in SARS-CoV-2 infection, which is associated with a variety of neurological manifestations such as headache, dizziness, and olfactory and gustatory disorders. This study provides an overview of the Pubmed, Google Scholar and Scopus databases; and the keywords SARS ‐ CoV-2, Covid-19, ACE2 and the nervous system were used to find articles related to the clinical data of SARS ‐ CoV-2 invasion of the nervous system. The published articles retrieved from 1992 to 2020. The findings suggest that coronaviruses invade the human nervous system and cause severe neurological changes. Therefore, given that the SARS-CoV-2 specific receptor; ACE2 is abundant in the central nervous system, and the neurological and invasive properties of other human coronaviruses have been widely reported, it is essential to identify possible complications of COVID-19 on the nervous system.

Introduction: COVID-19 is a highly contagious infectious disease caused by a new coronavirus that can be transmitted from person to person through close contact. The aim of the present study is to investigate new information in the field of COVID-19 immunology. Materials and Methods: The present study uses Google and Google Scholar search engines and articles indexed by reputable international scientific databases including Pub Med, MedLine, and the World Health Organization (WHO). In this study, published articles about COVID-19 and field of immunology were reviewed, and articles that did not have free access (Open Acess) and only access to abstracts were excluded from the study. Results: In total, studies have been suggested that the amount of cytokines such as IL-10, IL-7, IL-2, G-CSF, and TNF-α has been reported at high levels in patients. The ACE2 receptor is the target receptor for the Covid-19 virus, which binds to it after entering the lungs then IFN-I inhibit the primary replication and inhibition of the virus. Conclusion: After reviewing the articles, it was found that strengthening the immune system against viral infections is very important. The virus weakens the immune system by disrupting the production of type I interferon and reducing expression in the production of MHC-I, II. One of the best ways to fight COVID-19 is to get the right vaccine to boost immune system and produce T cells and cytokines.

Undoubtedly, vaccination can be one of the promising approaches to control infectious diseases such as the COVID-19 pandemic. Inactivated viral vaccines have a history of "vaccine-induced enhanced disease", which may occur when neutralizing antibodies bind to viral antigens without blocking or clearing the infection. This can cause additional inflammation through the mechanisms described for other respiratory pathogens and lead to acute respiratory distress syndrome. Since the structure and function of SARS-CoV-2 glycoproteins are well known, vaccine manufacturers appear to be careful when inactivating the virus to completely inactivate and maintain the viral epitopes necessary for protective immune induction. It seems that caution should be taken in the usage of inactivated vaccines in children to ensure they are safe and efficacious, vaccinated children should be well monitored and any symptoms should be reported immediately.

Background: The disease (COVID-2019) caused by (SARS-CoV-2) spread around the world. The new virus is a member of the Coronaviridae family and has been detected in various birds and mammals. The Spectrum of SARS-CoV-2 disease varies from asymptomatic infection to severe and often fatal disease. Immune responses against this SARS-CoV-2 are initiated by the innate immune system by the production of proinflammatory cytokines and chemokines. After that acquired immune responses begin, including cellular and hemoral immunity, are activated. The persistence of the antibody response to SARS-CoV-2 has not been determined precisely. There is a strong correlation between the neutralization antibody titer and the number of virus-specific T cells. The findings also show that both B and T cells participate in Immunological protection against viral infection. Understanding the behavior of SARS-CoV-2 in human host cells and its effect on the immune system can help to better understand the nature and pathogenesis of the virus. Furthermore, understanding the complexity of the function of immune system against the virus is necessary to developing new treatment protocols. However, there is a lot of controversy about the immune responses to this viral infection and its challenges, because the immune response against the SARS-CoV-2 virus is different from other coronavirus infections in many ways. According to the importance of this issue in this paper, while mentioning the structural features, virology of SARS-CoV-2 and its pathogenesis, immunological responses to this virus and the challenges are reviewed. For this purpose, review and original articles were collected from PubMed, Scopus, Google Scholar, and other reputable databases by using keywords such as COVID-19, Coronavirus, SARS-CoV-2, Pathogenesis, clinical features, Immune system, Antibody responses, B cell, T cell.