The epidemic of the 2019 novel coronavirus (severe acute respiratory syndrome coronavirus 2 – SARSCoV-2), which was first identified in Wuhan, a cityin the Hubei province in China, is being exported to a growing number of countries. Early efforts were focused on describing the clinical course, counting severe cases, and treating the disease1. Covid-19 has spread rapidly and has been shown to have a wide spectrum of severity. The World Health Organization (WHO) has recently declared coronavirus disease 2019 (Covid-19) a public health emergency of international concern2. So far, according to the World Health Organization3, COVID-19 has affected globally 1.210.956 individuals and accounted for over 67.594 deaths.
Since this is a new disease, the scientific community is engaged in new research that better explains the pathophysiology, diagnosis, clinical course, and treatment of coronavirus. Many works are published daily showing different outcomes of the disease, mainly regarding the symptoms and the treatment, which does not have one specific path so far, making it difficult to follow and understand the updates. This study will discuss information on what we know about Covid-19 so far to summarize and facilitate the access to information and a better understanding of this pandemic in order to contribute to the medical community in the decision-making and direct new studies on issues that remain limited about SARS-CoV2.
MATERIALS AND METHODS
Our study brings whats is known about the coronavirus so far and aims to gather essential information to better understand this pandemic and help on the next steps that the scientific community must take. This is a review article that brings collected information from different articles published since the beginning of the epidemic of the 2019 novel coronavirus [Pubmed “covid-19”; “coronavirus”; “H1N1 infection”]. There were no date or language restrictions. Information was collected in cohort studies (4), case series (11), non-randomized clinical trials (1), review articles (7), and others. The search was for information about the epidemiology, rate of infection, hospital care, incubation period, signs and symptoms, risk factors, confounding factors, and current treatment. The majority of the data on COVID-19 come from Asia. The electronic databases were last searched on 06 April 2020. The main papers used are listed in Table 1.
Rate of Infection
At the beginning of the outbreak, an association between the origin of COVID- 19 and the wet animal market in Wuhan City, where live animals are routinely sold, was identified19. But after the progression of the virus, the person-to-person transmission became the most important way of transmission. It occurs primarily via direct contact or through droplets spread by the coughing or sneezing of an infected individual19. Recently, SARS-Cov-2 was isolated from feces of patients with Covid-19 by Chinese researchers, indicating the potential of fecal oral transmission24. Moreover, a study detected a low prevalence of patients with positive results for SARS-CoV2 on RT-PCR in conjunctival swabs and suggested the possibility of transmission through the eyes7. Currently, there is no evidence for intrauterine vertical transmission of COVID-1924. Based on observations of data from the early outbreak in China, the trend of an increasing incidence largely follows exponential growth, and the mean basic reproduction number (R0) was estimated from 2.24 to 3.5820. The fraction of undocumented cases with mild, limited, or no symptoms is critical to the spread of coronavirus. Li et al.25 estimated the prevalence and contagiousness of these undocumented cases with a mathematical model of simulation. They found that patients with no reported infection are half as contagious, per individual, as reported ones. However, 86.2% (95%CI: 81.5-89.8) of all infections were from undocumented cases. Their simulation predicted that 78.8% of reported infections should have been reduced without transmission from undocumented cases25.
The incubation period is critical to understand the infectiousness of COVID-19, its epidemic size, and the ideal time for the quarantine period. It is defined as the period between the day of infection and the illness onset. Linton et al.15 found an average incubation period of 5.6 days (95%CI: 5.0,6.3) (n=158). Most infected people that present symptoms will do so within 12 days of the primary contact and the current period of active monitoring (14 days) is well supported by the evidence26.
Signs and symptoms
The symptoms may vary, according to studies, due to different samples, the period of analysis of the patients, and subjectivity of data. However, this review enabled a satisfactory survey of the main signs and symptoms. The most common symptoms at the onset of illness, according to the case series analyzed and represented in Table 2, were fever, cough, myalgia, fatigue, sputum production, and dyspnea [Table 2]. Some patients had radiographic evidence of pneumonia with bilateral diffuse airspace opacities. Some of which needed supplemental oxygen too6. Less common symptoms included hemoptysis, abdominal pain, diarrhea, nausea, and vomiting5. Sore throat and nasal congestion occurred in only around 5-10% of patients22.