The Covid-19 pandemic has mobilized the global scientific community. New discoveries about the characteristics and management strategies of the covid-19 disease are being uncovered by the hour. Here we cover the current accepted knowledge by the scientific community.
Covid-19 was initially recognized by the global community in December of 2019, however it’s believed that its first human infection occurred in the third week of November 2019. The first patients monitored showed slightly reduced white blood cells, lymphopenia, acute respiratory distress, and failure to improve with antibiotic treatment. Since these early days, much has been done by the global scientific community to better understand and treat this disease (such as the publication of the viral genome).
Viral characteristics
Covid-19 is a betacoronavirus. It shares 79% of its identity with SARS-CoV, even using the same ACE-2 receptors in the lungs for its entry into the human body. It is understood that the coronavirus family are zoonotic pathogens. Since close to 95% of its viral genome sequence is shared with bat coronaviruses, it highly hypothesized that Covid-19 originated in bats. However, this virus has yet to be identified in situ.
Clinical signs
The median age of patients infected is about 50 years old – however this number cannot be accurate, as younger patients with milder symptoms are less likely to present for clinical evaluation. The majority of patients examined presented with fever, chest “pain and tightness” and muscle fatigue. The majority of lower respiratory infections were bilateral.
Interestingly, very rarely do patients show signs of upper respiratory infection, including inflammation of the mucosal lining of the nose. Diarrhea is also a rare symptom assessed in one study.
Raised troponin levels in a small subset of patients examined indicated possible myocardial injury.
Transmission
It is understood now that the major cause of spread is human-to-human transmission. The virus has R0 of 1.4-2.5, which can lead to more than 2000 infections following 10 rounds of transmission. Human to human transmission is commonly due to inhaling aerosols from an infected individual, while transmission from surface to humans remains low. The virus has also been detected in patient stool samples.
Testing and diagnosis
By publishing the genome of the pathogen, the Chinese Centre of Disease Control and Prevention has lead the way for a reverse transcription polymerase chain reaction test, currently employed by most countries. In the future, since entire genome of the virus is known, methods of transmission and mutation can be better examined and prepared for.
Clinical management
To date, there is no antiviral or vaccine available. Covid-19 infections are largely managed with supportive care for lower severe respiratory distress. The current management guidelines are outlined by the WHO.
Our previous knowledge based on the SARS and MERS-CoV viruses show the lack of effect and harm of corticosteroid use – leading to delayed viral clearance and avascular necrosis.
A randomized clinical trial of lopinavir (a antiretroviral of the protease inhibitor class) has been started in Wuhan, China. In addition, a randomized clinical trial of remdesivir (a nucleotide analog retroviral) has started in the USA.