Outbreak of Novel Coronavirus (SARS-CoV-2): First Evidences From International Scientific Literature and Pending Questions
Conflicts of Interest
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|Documented Evidences||Scientific Suggestions||Pending Questions|
|Causative Agent||Family of Coronaviridae (genus: Betacoronavirus) enveloped positive single-stranded RNA [4,15].|
|Virus emergence||31 December, 2019 .||Emergence of SARS-CoV-2 into the human population likely occurred in mid-November 2019 .|
|Virus phylogenesis||SARS-CoV-2 is genetically very close to SARS-CoV, but sufficiently divergent to be considered a new human-infecting betacoronavirus .||Genome differences between SARS-CoV and SARS-CoV-2 could be responsible for the different functionality and pathogenesis.|
|Virus hosts||SARS-CoV-2 is 96% identical at the whole-genome level to a bat coronavirus .||Cat civets, snakes, and pangolins are indicated as potential intermediate hosts. Tracking the path of the virus could be crucial for preventing further exposure and outbreaks in the future.|
|Virus mutation rate and adaptation||The SARS-CoV-2 RNA sequences have limited variability and the estimated mutation rates in coronavirus, which SARS-CoV-2 phylogenetically links to, are moderate to high compared to the others in the category of ssRNA viruses . In healthcare workers, severity of disease showed a decreasing trend over time (critical or severe presentation was observed in 45%, 1–10 January, 2020; 19.7%, 11–20 January, 2020; 14.4%, 21–31 January, 2020; 8.7% after 1 February, 2020) .||The outbreak could be initiated from either a single introduction into humans or from very few animal-to-human transmission events. How SARS-CoV-2 evolves over time could have important implications for both strategic planning in public health interventions, prevention of, and development of vaccines and antibodies.|
|Virus environmental persistence||On inanimate surfaces, human coronaviruses can remain infectious for up to 9 days. A surface disinfection with 0.1% sodium hypochlorite, 0.5% hydrogen peroxide, or 62%–71% ethanol can be regarded as effective against coronaviruses within 1 min [15,17].|
|Virus spreading to human||SARS-CoV-2 spreads from person-to-person via respiratory droplets (coughs or sneezes) and possibly also via contaminated hands or surfaces. Close contact (within about 6 feet) increases risk of transmission .||The risk of transmission seems to be proportional to the severity of patient symptoms .|
|Immunity duration||As for other coronaviruses, in infected patients, humoral immunity might not be strong or long-lasting enough to keep them from contracting the disease again.|
|Incubation period||Current estimates suggest a mean incubation period of 6.4 days (95% credible interval: 5.6–7.7), with a range from 2.1 to 11.1 days (2.5th to 97.5th percentile) . To date, the maximum observed incubation period was 14 days .||A recent modelling study confirmed that it remains prudent to consider the incubation period of at least 14 days .||A longer incubation time may lead to a high rate of asymptomatic and subclinical infection among immunocompetent individuals. This finding could represents a key question for setting length of surveillance period for each at risk patient.|
|Basic reproductive number||A basic reproductive number of 3.28 has been estimated by a review (range between different studies 1.95 to 6.49) .||It is important to further assess the reason for the higher basic reproductive number values estimated by some mathematical studies. Reproductive number estimations produced at later stages can be expected to be more reliable, as they build upon more case data and include the effect of awareness and intervention. Variations in reproduction number could also be found over time, according to an improving capacity to detect cases.|
|Duration of the disease||To date, there are no evidences on this key point. The detection of SARS-CoV-2 and a high sputum viral load in a convalescent patient arouse concern about prolonged shedding of SARS-CoV-2 after recovery .|
|Asymptomatic carriers||There are evidences that SARS-CoV-2 appears to have been transmitted during the incubation period of a patient, in whom the illness was brief and nonspecific .||The fact that asymptomatic persons are potential sources of SARS-CoV-2 infection may warrant a reassessment of transmission dynamics of the current outbreak.|
|Frequent symptoms||In symptomatic patients, illness may evolve over the course of a week or longer, beginning with mild symptoms that progress (in some cases) to the point of dyspnea and shock . Most common complaints are fever (almost universal), cough, which may or may not be productive, whereas myalgia and fatigue are common . About 80% of identified cases were mild cases .|
|Severe clinical presentations||Most common complications are:|
(1) acute respiratory distress syndrome; (2) septic shock; (3) acute kidney injury; (4) myocardial injury; (5) secondary bacterial and fungal infections; (6) multiorgan failure [11,12]. About 14% of identified cases were severe and 4.7% critical .
|Case fatality rate||The updated case fatality rate of diagnosed cases is 2.3, with increasing risk for subjects aged 60 or older (3.6% in 60–69 year olds; 8% in 70–79 year olds, and 14.8% in subjects 80 or older), and in those with comorbidities (case fatality rate in healthy subjects was 0.9%) . Moreover, mortality rates seem to be decreasing over time (15.6%, 1–10 January, 2020; 5.7%, 11–20 January, 2020; 1.9%, 21–31 January, 2020; 0.8% after 1 February, 2020) .|
|Prevention in the general population||For the general public, the best way to prevent illness is to avoid being exposed to this virus. Face masks do not seem to be as effective in protecting those who are not infected, and wearing a mask could be useful only when taking care of a person with suspected COVID-19 .|
|Vaccines||There are currently no vaccines against coronaviruses, including SARS-CoV-2.||Various vaccine strategies against coronavirus, such as using inactivated viruses, live-attenuated viruses, viral vector-based vaccines, subunit vaccines, and recombinant proteins are under evaluation. However, several months may be required to undergo extensive testing to determine its safety and efficacy and before it can be widely used .|
|Therapies||At present, there is no single specific antiviral therapy for SARS-CoV-2 and the main treatments are supportive care (e.g., supportive therapy and monitoring—oxygen therapy and fluid management). Recombinant interferon (IFN) with ribavirin only has limited effects against CoVs infection .||Infusions of blood plasma from people who have recovered from the COVID-19 could represent a valid approach to treat those still battling the infection.|
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Amodio, E.; Vitale, F.; Cimino, L.; Casuccio, A.; Tramuto, F. Outbreak of Novel Coronavirus (SARS-CoV-2): First Evidences From International Scientific Literature and Pending Questions. Healthcare 2020, 8, 51. https://doi.org/10.3390/healthcare8010051
Amodio E, Vitale F, Cimino L, Casuccio A, Tramuto F. Outbreak of Novel Coronavirus (SARS-CoV-2): First Evidences From International Scientific Literature and Pending Questions. Healthcare. 2020; 8(1):51. https://doi.org/10.3390/healthcare8010051Chicago/Turabian Style
Amodio, Emanuele, Francesco Vitale, Livia Cimino, Alessandra Casuccio, and Fabio Tramuto. 2020. "Outbreak of Novel Coronavirus (SARS-CoV-2): First Evidences From International Scientific Literature and Pending Questions" Healthcare 8, no. 1: 51. https://doi.org/10.3390/healthcare8010051