BACKGROUND There is recently a concern regarding the reinfection and reactivation of previously reCoVered coronavirus disease 2019 (CoVID-19) patients. AIM To summarize the recent findings and reports of CoVID-19 reinfection in patients previously reCoVered from the disease. METHODS This study was a systematic review of current evidence conducted in August 2020. The authors studied the probable reinfection risk of novel coronavirus (CoVID-19). We performed a systematic search using the keywords in online databases. The investigation adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to ensure the reliability and validity of this study and results. RESULTS We reviewed 31 studies. Eight studies described reCoVered patients with reinfection. Only one study reported reinfected patients who died. In 26 studies, there was no information about the status of the patients. Several studies indicated that reinfection is not probable and that post-infection immunity is at least temporary and short. CONCLUSION Based on our review, we concluded that a positive polymerase chain reaction retest could be due to several reasons and should not always be considered as reinfection or reactivation of the disease. Most relevant studies in positive retest patients have shown relative and probably temporary immunity after the reCoVery of the disease.

Introduction It is reported that coronavirus disease (COVID-19) can affect the sense of smell and taste of infected people. The pathobiology of this virus is still incompletely known, and it is therefore important to explore the impact of COVID-19 infections on olfactory and gustatory functions. We aimed to review current evidence on olfactory and gustatory dysfunctions caused by COVID-19. Methods This study was a narrative review performed in 2020 to investigate the olfactory and gustatory dysfunctions of the COVID-19. We searched eight keywords in six databases to determine the related documents on the main objective of the study. To discover studies meeting the inclusion criteria, the authors screened the titles and abstracts of the identified articles. The appropriate studies were included and their results were discussed to make the final selection. Results We have studied 24 current articles on the olfactory and gustatory dysfunctions due to COVID-19. A review of current studies has shown that we have a surge in the spread of olfactory and gustatory dysfunctions that happened during the epidemic of COVID-19 infection. Most studies (95.8%) have confirmed the symptoms of anosmia in patients with SARS-CoV-2 infection. A review of current studies showed that, in addition to anosmia, evidence of ageusia and dysgeusia (parageusia) was also seen in patients with COVID-19. Conclusion The results of our study support recent reports that SARS-CoV-2 may infect oral and nasal tissues and cause olfactory and gustatory dysfunctions. These findings may aid future research on the diagnosis, prevention, and treatment of COVID-19 consequences.

Introduction Coronavirus Disease-2019 (SARS-CoV-2) started its devastating trajectory into a global pandemic in Wuhan, China, in December 2019. Ever since, several variants of SARS-CoV-2 have been identified. In the present review, we aimed to characterize the different variants of SARS-CoV-2 and explore the related morbidity and mortality. Methods A systematic review including the current evidence related to different variants of SARS-CoV-2 and the related morbidity and mortality was conducted through a systematic search utilizing the keywords in the online databases including Scopus, PubMed, Web of Science, and Science Direct; we retrieved all related papers and reports published in English from December 2019 to September 2020. Results A review of identified articles has shown three main genomic variants, including type A, type B, and type C. we also identified three clades including S, V, and G. Studies have demonstrated that the C14408T and A23403G alterations in the Nsp12 and S proteins are the most prominent alterations in the world, leading to life-threatening mutations.The spike D614G amino acid change has become the most common variant since December 2019. From missense mutations found from Gujarat SARS-CoV-2 genomes, C28854T, deleterious mutation in the nucleocapsid (N) gene was significantly associated with patients' mortality. The other significant deleterious variant (G25563T) is found in patients located in Orf3a and has a potential role in viral pathogenesis. Conclusion Overall, researchers identified several SARS-CoV-2 variants changing clinical manifestations and increasing the transmissibility, morbidity, and mortality of COVID-19. This should be considered in current practice and interventions to combat the pandemic and prevent related morbidity and mortality.

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Introduction Since the outbreak of the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) began, necessary measures to prevent virus transmission and reduce mortality have been implemented, including mandatory public use of masks, regular hand-sanitizing and hand-washing, social distancing, avoidance of crowds, remote work, and cancellation of public events. During and after the introduction of COVID-19 lockout, we performed a systematic review of available published literature to investigate the incidence of seasonal influenza and other respiratory viral infections. Methods PubMed, Embase, Web of Science, Scopus, Science Direct, Google Scholar, Research Gate, and the World Health Organization databases and websites were systematically searched for original studies concerning the impact of COVID-19 prevention means and measures on other common respiratory infectious diseases during the pandemic published by March 2021. Results The findings showed that the adherence to health protocols to prevent COVID-19 could help to reduce the incidence of other infectious diseases such as influenza, pneumonia, and Mycobacterium tuberculosis. Conclusion The implemented prevention measures and protocols might have reduced the incidence of influenza and some other common respiratory infections. However, controversies exist on this matter and future large population-based studies might provide further information to address these controversies.

Introduction: Many potential vaccines for COVID-19 are being studied, and several studies have reported the results of these vaccines. We aimed to review the current evidence of the feasibility and effectiveness of Vaccines for COVID-19. Methods: A search was carried out utilizing the keywords in the online databases, including Scopus,Web of Science, PubMed, Embase, and Cochrane. We included both human and non-human studies because of the vaccine novelty, which could limit our ability to include sufficient human studies. Results: The review of studies showed that several SARS-CoV-2 vaccines are under development; different platforms are being used, including eight vaccines are adenovirus-based vectors, six vaccines are RNA-based formulations, one vaccine is DNA-based formulations, and other vaccines are using other platforms, including lipid nano particles. Conclusion: It is crucial to gather as much clinically relevant evidence as possible regarding the immunogenicity, efficacy, and safety profiles of these vaccines and adhere wisely to CDC protocols and guidelines of vaccine production.

Background: The Coronavirus disease 19 (COVID-19) is a highly transmittable viral infection that initiated in Wuhan, China and has spread around the world. The high prevalence and spread ways of COVID-19 have become an international challenge that requires careful consideration. We aimed to review the current evidence of COVID-19 transmission modes. Methods: This study was a systematic review that was done to identify current evidence on transmission modes of COVID19. We searched selected keywords in six important databases to discover related sources on the main objective of the study. To identify studies meeting the inclusion criteria, the authors screened the titles and abstracts of retrieved documents. The appropriate articles were selected and their results were discussed to make the final inclusion. Results: We identified five potential transmission modes of COVID-19 including airborne, droplet, contact with contaminated surfaces, oral and fecal secretions. Furthermore, some studies have pointed out other modes of virus transmission, such as person to person, and direct contact with animals. Conclusion: Droplet and contact with contaminated surfaces were the most frequent transmission modes of COVID-19. Fecal excretion, environmental contamination, and fluid pollution might contribute to a viral transmission. The possibility of fecal transmission of COVID-19 has implications, especially in areas with poor sanitation and the environmental pollution can be caused by patients with SARS-CoV-2 through respiratory droplets and feces, subsequently, the human environment will change to a potential medium of virus transmission.

Introduction: SARS-CoV-2 is the novel coronavirus that causes severe acute respiratory syndrome and could afflict individuals from all walks of life. Children are usually asymptomatic or represent non-specific mild to moderate symptoms; therefore, they often remain undiagnosed and could be potential reservoirs and silent carriers of the virus. Despite the global attention to COVID-19 and its importance in public health, some clinical and paraclinical aspects of this disease in children are still unclear. Thus, we conducted a comprehensive systematic review of available literature to reflect on the current knowledge and practice of the disease among children. Methods: This study was a systematic review of current evidence conducted in October 2020. We performed a systematic search using the keywords in online databases. The investigation adheres to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist to ensure the reliability and validity of extracted literature and results. Results: We selected and reviewed 23 most related studies out of 1744 identified paper in an initial online search based on the inclusion and exclusion criteria of the present review; of whom, 13 were original research studies, and 10 were a letter to the editors, commentaries, viewpoints, consensus statements, and perspectives. Although due to the origin of the current pandemic, China was the country with the most publications (14 articles), data from several countries have beenincluded in this review. Conclusion: COVID-19 can also affect children and cause systemic disease with several internal organ involvements. However, the prevalence, severity, and diversity of the symptoms in children are less than in adults. Cough and fever appear to be some of the most common symptoms, followed by other symptoms such as gastrointestinal manifestations. Comorbidities increase the risk of severe COVID-19 in children, and those without underlying conditions are very unlikely to suffer from severe disease. Mental health issues such as anxiety and depression due to the isolated situation caused by pandemics are common findings in children of early ages and should be seriously considered in current practice.