Severe acute respiratory syndrome (SARS), Middle East respiratory syndrome (MERS), influenza, and COVID-19, beyond the lungs: a review article.

BACKGROUND: In the past 20 years four major viral infectious diseases outbreaks caused hundreds of thousands of deaths worldwide: SARS, Influenza H1N1, MERS, and COVID-19. They all present clinically initially as upper and lower respiratory tract infections and may progress to multi-organ failure. METHODS: This study was a systematic review of literature conducted in September 2020 to study extra-pulmonary complications of SARS, FLU, MERS, and current COVID-19. We carried out a systematic search using the keywords in online databases of PubMed, EMBASE, and Google Scholar until June 2020. OBJECTIVE: This article aims to review the most common extra-pulmonary manifestations of SARS, Influenza, MERS, and COVID-19. DISCUSSION: Several studies have reported extra-pulmonary conditions in patients diagnosed with SARS, Influenza, MERS, and COVID-19, either by direct viral injury or from the systemic response to the initial infection. CONCLUSION: SARS, Influenza, MERS, and COVID-19 have all been associated with dysfunction of kidneys, endocrine system, neuromuscular symptoms, perinatal complications, and myocardial injury. Progression from pulmonary disease to a systemic condition has a poor outcome and can result in multi-organ failure.

The relationship between COVID-19 viral load and disease severity: A systematic review.

INTRODUCTION: Patients with COVID-19 may present different viral loads levels. However, the relationship between viral load and disease severity in COVID-19 is still unknown. Therefore, this study aimed to systematically review the association between SARS-CoV-2 viral load and COVID-19 severity. METHODS: The relevant studies using the keywords of "COVID-19" and "viral load" were searched in the databases of PubMed, Scopus, Google Scholar, and Web of Science. A two-step title/abstract screening process was carried out and the eligible studies were included in the study. RESULTS: Thirty-four studies were included from the initial 1015 records. The vast majority of studies have utilized real-time reverse transcription-polymerase chain reaction of the nasopharyngeal/respiratory swabs to report viral load. Viral loads were commonly reported either as cycle threshold (Ct ) or log10 RNA copies/ml. CONCLUSION: The results were inconclusive about the relationship between COVID-19 severity and viral load, as a similar number of studies either approved or opposed this hypothesis. However, the studies denote the direct relationship between older age and higher SARS-CoV-2 viral load, which is a known risk factor for COVID-19 mortality. The higher viral load in older patients may serve as a mechanism for any possible relationships between COVID-19 viral load and disease severity. There was a positive correlation between SARS-CoV-2 viral load and its transmissibility. Nonetheless, further studies are recommended to precisely characterize this matter.