Pathophysiology, Transmission, Diagnosis, and Treatment of Coronavirus Disease 2019 (COVID-19)

Abstract

IMPORTANCEThe coronavirus disease 2019 (COVID-19) pandemic, due to the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), has caused a worldwide sudden and substantial increase in hospitalizations for pneumonia with multiorgan disease. This review discusses current evidence regarding the pathophysiology, transmission, diagnosis, and management of COVID-19.OBSERVATIONS SARS-CoV-2 is spread primarily via respiratory droplets during close face-to-face contact. Infection can be spread by asymptomatic, presymptomatic, and symptomatic carriers. The average time from exposure to symptom onset is 5 days, and 97.5% of people who develop symptoms do so within 11.5 days. The most common symptoms are fever, dry cough, and shortness of breath. Radiographic and laboratory abnormalities, such as lymphopenia and elevated lactate dehydrogenase, are common, but nonspecific. Diagnosis is made by detection of SARS-CoV-2 via reverse transcription polymerase chain reaction testing, although false-negative test results may occur in up to 20% to 67% of patients; however, this is dependent on the quality and timing of testing. Manifestations of COVID-19 include asymptomatic carriers and fulminant disease characterized by sepsis and acute respiratory failure. Approximately 5% of patients with COVID-19, and 20% of those hospitalized, experience severe symptoms necessitating intensive care. More than 75% of patients hospitalized with COVID-19 require supplemental oxygen. Treatment for individuals with COVID-19 includes best practices for supportive management of acute hypoxic respiratory failure. Emerging data indicate that dexamethasone therapy reduces 28-day mortality in patients requiring supplemental oxygen compared with usual care (21.6% vs 24.6%; age-adjusted rate ratio, 0.83 [95% CI, 0.74-0.92]) and that remdesivir improves time to recovery (hospital discharge or no supplemental oxygen requirement) from 15 to 11 days. In a randomized trial of 103 patients with COVID-19, convalescent plasma did not shorten time to recovery. Ongoing trials are testing antiviral therapies, immune modulators, and anticoagulants. The case-fatality rate for COVID-19 varies markedly by age, ranging from 0.3 deaths per 1000 cases among patients aged 5 to 17 years to 304.9 deaths per 1000 cases among patients aged 85 years or older in the US. Among patients hospitalized in the intensive care unit, the case fatality is up to 40%. At least 120 SARS-CoV-2 vaccines are under development. Until an effective vaccine is available, the primary methods to reduce spread are face masks, social distancing, and contact tracing. Monoclonal antibodies and hyperimmune globulin may provide additional preventive strategies.CONCLUSIONS AND RELEVANCE As of July 1, 2020, more than 10 million people worldwide had been infected with SARS-CoV-2. Many aspects of transmission, infection, and treatment remain unclear. Advances in prevention and effective management of COVID-19 will require basic and clinical investigation and public health and clinical interventions.

Epidemic Dynamics of COVID-19 Based on SEAIUHR Model Considering Asymptomatic Cases in Henan Province, China

“…Due to the absence of clinical symptoms such as coughing and sneezing, the chance of transmission caused by the pathogen being discharged from the body of an asymptomatic case was relatively less than that of a symptomatic one. Our model estimated that the mean ratio of transmission rate due to asymptomatic over symptomatic cases was 0.1, corresponding to study showing that prolonged exposure to infected persons and short exposure to symptomatic persons (such as coughing) is associated with a higher risk of transmission, while short exposure to asymptomatic contacts is associated with a lower risk of transmission [27].…”

“…Parameters latent period( ) 3 days (Fixed) [2,27,[33][34][35] Infectious period of confirmed symptomatic cases ( 1 ) 3.5 days (Fixed) [5,19,31,32] Infectious period of asymptomatic cases ( 2 ) 5 days (Fixed) [16] Infectious period of unconfirmed symptomatic cases ( 3 ) 5 days (Fixed) [16] Duration removed from hospitalization ( ) 10 days (Fixed) [36] Transmission rate due to symptomatic cases ( 0 ) U(0.8,1.5) (Estimated) The ratio of transmission rate ( ) 0.10(0.02,0.11)…”

The Asymptomatic Infection of COVID-19 Risen in Imported Population in Shenzhen, China

“…To this end, it is critical to take strict prevention and control measures, strictly isolate and test the entrants to the city, screen out asymptomatic infections, implement strict medical quarantine and observation measures, and perform active and early treatment, so as to avoid further spread of COVID-19. At present, with the global pandemic of COVID-19 [27], which has no de ned duration, there is always a risk of imported sources of infection and China will always face the risk of imported cases as long as the pandemic is not under effective control, and as insidious sources of transmission, asymptomatic infections may also be one of the major risks in the future development of COVID-19 [28]. Thus, normalized prevention and control measures are required for the prevention and control of COVID-19 at such a time when there are few local cases and a few imported cases and asymptomatic infections [27].…”

Myocardial Injury in Post Mortem Biopsies of Patients with COVID-19

“…The heart failure may contribute up to 40% of deaths, and circulatory failure may be the death cause even without respiratory failure 3 . Prothrombotic coagulopathy have been also described in 25% of patients resulting in venous and arterial thromboembolic events 5 .…”