Coronavirus 2019 Infectious Disease Epidemic: Where We Are, What Can Be Done and Hope For

Abstract

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spreads mainly by means of aerosols (microdroplets) in enclosed environments, especially those in which temperature and humidity are regulated by means of air-conditioning. About 30% of individuals infected with SARS-CoV-2 develop coronavirus disease 2019 (COVID-19) disease. Among them, approximately 25% require hospitalization. In medicine, cases are identified as those who become ill. During this pandemic, cases have been identified as those with a positive SARS-CoV-2 polymerase chain reaction test, including approximately 70% who were asymptomatic-this has caused unnecessary anxiety. Individuals more than 65 years old, those affected by obesity, diabetes, asthma, or are immune-depressed owing to cancer and other conditions, are at a higher risk of hospitalization and of dying of COVID-19. Healthy individuals younger than 40 years very rarely die of COVID-19. Estimates of the COVID-19 mortality rate vary because the definition of COVID-19-related deaths varies. Belgium has the highest death rate at 154.9 per 100,000 persons, because it includes anyone who died with symptoms compatible with COVID-19, even those never tested for SARS-CoV-2. The United States includes all patients who died with a positive test, whether they died because of, or with, SARS-CoV-2. Countries that include only patients in which COVID-19 was the main cause of death, rather than a cofactor, have lower death rates. Numerous therapies are being developed, and rapid improvements are anticipated. Because of disinformation, only approximately 50% of the U.S. population plans to receive a COVID-19 vaccine. By sharing accurate information, physicians, health professionals, and scientists play a key role in addressing myths and anxiety, help public health officials enact measures to decrease infections, and provide the best care for those who become sick. In this article, we discuss these issues.

Keywords: COVID-19; COVID-19 transmission; Coronavirus; SARS-CoV-2; pandemic.

Figure 1

rRT-PCR detection of SARS-CoV-2 vRNA in a nasopharyngeal swab from a patient with COVID-19. The Cq value of the patient specimen is 25.84, and the positive control 31.97. No signal was generated by the negative control. There is an inverse relationship between Cq and target amplification; the lower the Cq, the higher the amount of SARS-CoV-2 in the RT-PCR. The specificity of most of the frequently used RT-PCR tests is 100% because the primer design is specific to the genome sequence of SARS-CoV-2. Nevertheless, the sensitivity of detection varies between the RT-PCR tests. The cycle at which amplification exceeds the background fluorescence is expressed as the quantification cycle (which some refer to as Cq and some as Ct). This is the new standardized term for reporting rRT-PCR results on the basis of MIQE guidelines. COVID-19, coronavirus disease 2019; Cq, quantitation cycle; Ct, cycle threshold; MIQE, Minimum Information for Publication of Quantitative Real-Time PCR Experiments; RFU, relative fluorescence unit; rRT-PCR, real-time reverse transcriptase-polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus-2; vRNA, virus genomic RNA.

Figure 2

Infectivity window. The period of time during which infectious virus can be isolated and grown in cell culture is shown in gray, the detection of viral RNA by RT-PCR in red, the development of specific IgG in red. Virus isolation may vary significantly among different laboratories depending on the skills of those involved. Detection of viral sequences by RT-PCR may last longer than viral isolation as noninfectious viral particles are released. The length of time of IgG persistence is uncertain at this time. IgG, immunoglobulin G; RT-PCR, reverse transcriptase-polymerase chain reaction.

Figure 3

Wuhan. Left, crowded ER in Wuhan before the lockdown, patients with cough, fever, and other respiratory symptoms crowded the ER together with patients with other conditions. This is where the epidemic spread rapidly in the early phases of the pandemic. Right, the first day of lockdown in Wuhan, the main commercial street is desert. ER, emergency room.

Figure 4

Lung pathology of a patient with COVID-19. Focal hyaline membrane (red arrow) indicating DAD, mild inflammatory infiltration, thickening of alveolar septa in adjacent areas. COVID-19, coronavirus disease 2019; DAD, diffuse alveolar damage.

Figure 5

SARS-CoV-2 infection stages over time: the relationship between disease severity and viral burden, host hyperinflammation response, bacterial and fungal superinfections, and postinfectious sequelae. ARDS, acute respiratory distress syndrome; BSIs, bloodstream infection; CAPA, COVID associated pulmonary aspergillosis; COVID, coronavirus disease; FiO₂, fraction of inspired oxygen; ICU, intensive care unit; PaO₂, partial pressure of oxygen; pt, patient; SARS-CoV-2, severe acute respiratory syndrome coronavirus-2; SIRS, systemic inflammatory response syndrome; VAP, ventilator-associated pneumonia.

Figure 6

Thin-section computed tomography. (A) Initial subpleural GGO often found in most patients with COVID-19 requiring hospital admission. (B) diffuse GGOs going toward attenuation with superimposed interlobular septal thickening and intralobular lines (crazy-paving pattern). This imaging is often seen in patients with COVID-19 when they are developing, or have developed, ARDS and require treatment in the ICU. Similar GGOs can be found in various other pathologies, including lung cancer, lung fibrosis, drug injury, inflammation, and hemorrhage; however, in regions experiencing a COVID-19 epidemic, their presence alerts clinicians about possible COVID-19 pneumonia and should trigger PCR testing for SARS-CoV-2. C, D reveal different levels of thin-sections of computed tomography scans of the lungs on admission in ICU in a 44-year-old man requiring urgent intubation for SARS-Cov-2 infection. (C) multiple GGOs in both lungs. (D) large consolidation in the right upper lobe. In this patient, PCR nasopharyngeal swab testing was positive, pneumococcal and Legionella antigenuria were negative; cultures of the bronchoalveolar fluid yielded no microbial growth but a positive galactomannan index of 1,9. The final diagnosis was SARS-CoV-2 and invasive aspergillosis coinfection. ARDS, acute respiratory distress syndrome; COVID-19, coronavirus disease 2019; GGO, ground-glass opacity; ICU, intensive care unit; PCR, polymerase chain reaction; SARS-CoV-2, severe acute respiratory syndrome coronavirus-2.