Coronaviruses belong to the family of RNA viruses that infect humans, birds and other mammals causing a plethora of disease presentations involving the gastrointestinal, respiratory and neurologic systems. Most coronaviruses cause mild respiratory symptoms consistent with the common cold. However, there have been two lethal subtypes that have been previously identified, including the acute respiratory syndrome coronavirus (SARS-CoV) in 2002 demonstrating 10% mortality and the Middle East respiratory syndrome coronavirus (MERS-CoV) in 2012 causing 37% mortality.
In December 2019, a novel coronavirus (2019-nCoV) was isolated from a cluster of patients with pneumonia in Wuhan, China, a large city with a population of 11 million people. Detailed analysis of the viral RNA sequencing showed the 2019-nCoV to have a primary reservoir in bats. However, the means of transmission directly to humans or through an intermediary host has not yet been elucidated. The most recent data estimates the mean incubation period (time elapsed between exposure to the pathogen and when symptoms are first apparent) to be approximately five days.
Prehospital providers are the first line of contact with patients who show signs and symptoms of a viral infection. It is therefore crucial to identify those individuals who are at high risk for contracting the 2019-nCoV based on their symptoms and travel history.
A case series of 41 patients in Wuhan, China with confirmed 2019-nCoV revealed that the most common presenting symptoms include fever (98%), cough (76%), dyspnea (55%) and myalgias (44%). The median age was 49 years. Less than half of patients had comorbid conditions, like diabetes or cardiovascular disease. One third of patients required admission to the intensive care unit (ICU), typically for respiratory support for acute hypoxic respiratory failure.
Dyspnea occurred at a median of eight days after symptom onset and acute respiratory distress syndrome (ARDS) developed at a median of nine days. Chest CT was abnormal in all cases consistent with pneumonia and 98% of patients had bilateral consolidation and/or ground glass opacity. ARDS developed in 29% of patients. All patients were treated empirically for influenza and bacterial pneumonia. The observed mortality in this case series of patients with 2019-nCoV was 15% and as of January 22, 2020, 68% of the cohort was discharged. More recent mortality rate estimates comprising nearly 800 reported cases are closer to 3%.
The clinical presentation of patients infected with 2019-nCoV differs from SARS-CoV and MERS-CoV based on the absence of upper respiratory symptoms like rhinorrhea, sneezing or sore throat, localizing the novel virus to the lower airway. Additionally, gastrointestinal symptoms are less common with 2019-nCoV, while approximately one quarter of SARS-CoV and MERS-CoV patients had diarrhea.
Currently, no specific antiviral therapy for 2019-nCoV is available. The 2019-nCoV remains under intense monitoring by the CDC, given the risk of a pandemic. As directed by the CDC, healthcare workers must screen patients with fever, cough and dyspnea in the United States for travel to China or other affected regions in the past two weeks. Transmission of 2019-nCoV is suspected to occur by large droplets and contact rather than aerosols. Patients with suspected novel coronavirus infection should have a facemask placed over mouth and nose and be rapidly isolated in an airborne infection isolation room. Healthcare workers should adhere to standard contact and airborne isolation, utilize eye protection and perform hand hygiene with soap and water.
References
– Centers for Disease Control and Prevention (CDC): National Center for Immunization and Respiratory Diseases (NICRD), Division of Viral diseases. 2019 Novel Coronavirus, Wuhan, China. Retrieved from: https://www.cdc.gov/coronavirus/2019-nCoV/clinical-criteria.html.
– Perlman S. Another decade, another coronavirus. New Engl J Med [Internet]. 2020 Jan 24;1-2. Available from:https://www.nejm.org/doi/full/10.1056/NEJMe2001126?query=featured_home.
– Zhu N, et al. A novel coronavirus from patients with pneumonia in China, 2019. New Engl J Med [Internet]. 2020 Jan 24;1-7. Available from: https://www.nejm.org/doi/pdf/10.1056/NEJMoa2001017?articleTools=true.
