1. Overview of COVID-19

Welcome to Viruswatch! Your source for short and sweet updates about all things COVID-19. Today we’re starting off with the basics and covering a broad overview of what you NEED to know about this novel coronavirus; with a particular focus on virus transmission. Note that many topics will be explored in more depth in later episodes – stay tuned!

 

What is COVID-19?

COVID-19 is the name that has been given to the disease caused by the novel coronavirus (aka SARS-CoV-2) It is a 30kbp, +ssRNA virus suspected to have originated in bats1 Coronaviruses are a family of viruses Found predominantly in animals In humans: most often cause the common cold Can cause severe disease like SARS (Severe Acute Respiratory Syndrome – aka SARS-CoV-1) or MERS (Middle Eastern Respiratory Syndrome) SARS-CoV-2 binds the ACEII receptor (alveolar cells, vascular/intestinal endothelium)2

 

Virus transmission

Controversial area! Known spread via droplet transmission: large droplets expelled from the respiratory tract during close contact The WHO and CDC suggest this is the primary mode of spread3,4 Fomite spread Evidence that the virus remains active on environmental surfaces for prolonged periods, suggesting the potential for spread via fomites. Regular cleaning and disinfecting protocols kill these viruses5 Half-life is longest on plastic and stainless steel (virus detected up to 72h)5 Airborne spread? Aerosolized spread is possible during aerosol-generating procedures such as intubation, bronchoscopy, non-invasive positive-pressure ventilation, etc. An old study showing that aerosolized coronavirus (in lab conditions) may survive in ambient air up to 6 hours6 One group took surface environmental samples from the airborne isolation rooms of several COVID patients à found that all air samples were negative, but air duct samples as well as one shoe sample from a HCW was positive7 Inconclusive evidence about the impact of airborne spread8 Questions remain about spread via stool, blood, other modes Important caveats about mode of transmission! Many studies to date: Use artificial set-ups to simulate real world conditions (ie putting virus into a nebulizer) Look for the presence of viral RNA on various surfaces à don’t know that actual implications of this would be for infectivity! Asymptomatic spread Asymptomatic, pre-symptomatic, and minimally symptomatic spread are now believed to be possible9 In many studies, significant percentage of patients testing positive were asymptomatic or minimally symptomatic at the time of the positive test This has significant infection control implications, and also raises the question of the efficacy of various workplace screening protocols The R0 (parameter of infectivity) is thought to be between 2 to 3, though this will vary significantly depending on environment and human behavior

 

Clinical Presentations

There appear to be three primary phenotypes for COVID 19 Asymptomatic/presymptomatic/minimally symptomatic carriers Febrile respiratory illness (ILI: influenza-like illness) GI illness (small minority of patients have only GI symptoms)10 Symptoms to look out for include fever, cough, shortness of breath, upper respiratory tract symptoms, malaise, fatigue, nausea, vomiting, diarrhea, abdominal pain As case numbers have skyrocketed, more people are presenting with atypical features: failure to thrive, electrolyte abnormalities, chest pain, neurologic deficits/stroke, etc Investigations Most common lab abnormality is lymphopenia Inflammatory markers such as CRP, D-dimer, ferritin may help determine phase of illness and identify those at higher risk of deterioration Cardiac enzymes (troponin, BNP) and liver enzymes (AST/ALT) may also be elevated Coagulation parameters often abnormal Imaging CXR typically reveals patchy bilateral infiltrates May be normal in early/mild disease POCUS: inflammatory B-line pattern (patchy B-lines with irregular/thickened pleura) CT scan: typical findings include bilateral ground-glass opacities with a lower lobe predominance11 Biphasic disease course: late hyperinflammatory phase It’s been recognized that some patients experience abrupt clinical deterioration late in their disease course, attributed to an HLH-like immune hyperactivation12 Hypercoagulability seems to be important: high indigence of abnormal coagulation parameters and clinical VTE13

 

 Testing

Testing is currently done via RT-PCR assay of NP swab Reported test characteristics vary; sensitivities range from 60-80% in informal reports Suboptimal NP swab technique Primarily lower respiratory/GI tract burden of virus Phase of illness: v early disease OR past the viral replicative phase Who gets tested? Check with your local health authority/regional guidelines

 

 

Disease severity

Most patients have mild illness and do not require hospitalization Initial figures were about 80%; this may be higher as we recognize that large numbers of people may be asymptomatic and unaware of their infection Of those requiring hospitalization: about 5% seem to have critical illness14 This number varies significantly in different cohorts and as the pandemic evolves

 

Treatment

Treatment for COVID-19 is supportive Treat hypoxemia with supplemental O2 Treat symptoms: analgesia, antipyretics, anti-emetics, etc There are no proven therapies at this point though several are under investigation In particular, at this point: Steroids are not routinely* recommended for all COVID-19 Recommended in a subset of critically ill patients Hydroxychloroquine is not routinely recommended for COVID-19 Anti-virals and antibiotics are not routinely recommended for COVID-19 Full-dose anticoagulation for patients without clinical evidence of VTE is not routinely recommended for COVID-19 Use of these therapies should occur: Within the context of clinical trials As directed by your unit/hospital/health authority See future podcasts for all the nitty gritty details about therapies!

 

 

 

 

 

Sources

Guo, Y., Cao, Q., Hong, Z. et al. The origin, transmission and clinical therapies on coronavirus disease 2019 (COVID-19) outbreak – an update on the status. Military Med Res 7, 11 (2020). doi: 10.1186/s40779-020-00240-0

 

Hamming I, Timens W, Bulthuis ML et al. Tissue distribution of ACE2 protein, the functional receptor for SARS coronavirus. A first step in understanding SARS pathogenesis. J Pathol, 2004 Jun;203(2):631-7. doi: 10.1002/path.1570

 

Modes of transmission of virus causing COVID-19: implications for IPC precaution recommendations. WHO scientific brief, March 29 2020. https://www.who.int/news-room/commentaries/detail/modes-of-transmission-of-virus-causing-covid-19-implications-for-ipc-precaution-recommendations

 

CDC Interim Infection Prevention and Control Recommendations for Patients with Suspected or Confirmed Coronavirus Disease 2019 (COVID-19) in Healthcare Settings. April 13 2020. https://www.cdc.gov/coronavirus/2019-ncov/hcp/infection-control-recommendations.html

 

Doremalen N, Morris D, Holbrook M et al. Aerosol and surface stability of SARS-CoV-2 as compared with SARS-CoV-1. N Engl J Med, 2020; 382:1564-1567. doi: 10.1056/NEJMc20049733

 

Pyankov O, Bodnev S, Pyankova O et al. Survival of aerosolized coronavirus in ambient air. Journal of Aerosol Science, 2018,115:158-163. doi: 10.1016/j.jaerosci.2017.09.009

 

Ong SWX, Tan YK, Chia PY, et al. Air, Surface Environmental, and Personal Protective Equipment Contamination by Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) From a Symptomatic Patient. JAMA. 2020;323(16):1610–1612. doi: 10.1001/jama.2020.3227

 

Rubens J, Karakousis P, Jain S et al. Stability and viability of SARS-CoV-2. New Eng J Med, April 2020. doi: 10.1056/NEJMc2007942

 

Ganhdi M, Yokoe D, Havlir D. Asymptomatic Transmission, the Achilles’ Heel of Current Strategies to Control Covid-19. New Eng J Med, April 2020. doi: 10.1056/NEJMe2009758

 

Pan L, Mu M, Yang P et al. Clinical characteristics of COVID-19 patients with digestive symptoms in Hubei, China: a descriptive, cross-sectional, multicenter study. Am J Gastroenterol. 2020 May;115(5):766-773. doi: 10.14309/ajg.0000000000000620

 

Karimian, M and Azami, M. Computed Tomography Scan Findings in Patients with COVID-19: A Systematic Review and Meta-Analysis (4/4/2020). Lancet pre-prints. Available at SSRN: https://ssrn.com/abstract=3571539


1. Siddiqi S and Mera M. COVID-19 Illness in Native and Immunosuppressed States: A Clinical-Therapeutic Staging Proposal. J Hear Lung Transplant, 2020,29(5):405-407. doi: 10.1016/j.healun.2020.03.012
   

 

1. Thachil J, Tang N, Gando S et al. ISTH interim guidance on recognition and management of coagulopathy in COVID‐19. J Thromb Haemost, 2020. doi: 10.1111/jth.14810
   

 

1. Wu Z, and McGoogan JM. Characteristics of and Important Lessons From the Coronavirus Disease 2019 (COVID-19) Outbreak in China: Summary of a Report of 72 314 Cases From the Chinese Center for Disease Control and Prevention. JAMA.2020;323(13):1239–1242. doi:10.1001/jama.2020.2648