Epidemiology of COVID-19

Abstract

IntroductionCoronoviruses have been reported as causes of mild and moderate respiratory infections forover 50 years [1]. Even though this group of viruses have been isolated from many different animals, bats are accepted major natural reservoir of coronaviruses [2,3].Four human coronavirus, 229E, HKU1, NL63 and OC43, are known as causes of common cold in humans [1]. However, recently-detected coronaviruses, SARS CoV (2002), MERS-CoV (2012) completely altered all known approaches about this virus group because these viruses caused severe acute respiratory infections and nosocomial outbreaks. In the end of 2019, a novel coronavirus, now known as SARS-CoV-2 (2019), suddenly emerged in Wuhan, China. The World Health Organization declared that the epidemic is a public health emergency of international concern on January 31, 2020. As of April 16, 2020, the emerging coronavirus infection, COVID-19, has been spreading worldwide, causing over 2 million cases and over 137 thousand of death.In as much as this disease recently taken a significant place in our daily practice, as a new group of respiratory diseases, due to their higher rates of transmissibility, hospitalization, intensive care unit admission, severity of disease, mortality and so on, we should pay more attention than past to prevention and treatment of coronavirus infection. Origin of the SARS CoV-2 virusThe first cases of coronavirus disease COVID-19 were directly related to an animal market in Wuhan, China. Early investigations suggested that the origin of SARSCoV-2 may be bats. Zhou et al. demonstrate that SARS CoV-2 possesses 96% nucleotide identity with a bat coronavirus, for instance BetaCoV/RaTG13/2013 [4]. Epidemic curve of infectionAn epidemic curve of infection is a statistical chart used in epidemiology to visualize the onset of the coronavirus outbreak. In an epidemic curve, there are three zones: increasing, plateau, and declining phases.Increasing phase: This period is affected by many different parameters such as country demographics, age distribution, preparedness of health system to an outbreak, implementation of some preventive measures, country reaction time to a pandemic, reaction of society to new implementing rules. Different countries can exhibit quite different curve patterns and these facts could complicate

Involvement of the Nervous System in SARS-CoV-2 Infection

“…On February 11, 2020, the World Health Organization named this infection coronavirus disease-2019 (COVID-19) (Lai et al 2020a). Although the mortality rate of COVID-19 is currently lower than that of SARS, as of April 16, 2020, COVID-19 has causing more than 2 million cases and over 137 thousand deaths (Bulut and Kato 2020). Therefore, COVID-19 has become a global public health problem, and the World Health Organization classifies the global threat level of coronavirus as very high and designated the COVID-19 outbreak a pandemic (Bulut and Kato 2020).…”

“…Although the mortality rate of COVID-19 is currently lower than that of SARS, as of April 16, 2020, COVID-19 has causing more than 2 million cases and over 137 thousand deaths (Bulut and Kato 2020). Therefore, COVID-19 has become a global public health problem, and the World Health Organization classifies the global threat level of coronavirus as very high and designated the COVID-19 outbreak a pandemic (Bulut and Kato 2020). Growing evidence indicates that SARS-CoV-2 also affects different organs and systems, including the central nervous system (CNS).…”

Epidemiological Characteristics of COVID-19 under Government-mandated Control Measures in Inner Mongolia, China

“…Asymptomatic infection also a critical source of COVID-19 [24]. A study on COVID-19 asymptomatic infection showed that an asymptomatic infection may cause infection in 5 people from exposure to con rmed [25]. At that time, the whole country, including Inner Mongolia, a large number of people were returned to work or school.…”

Multivariate Prediction Network Model for epidemic progression to study the effects of lockdown time and coverage on a closed community on theoretical and real scenarios of COVID-19

“…However, new estimates on pandemic progression have obtained a R0 of 5.7 and a growth rate of 0.21-0.3/day (Sanche et al, 2020). Other recent sources have indicated reproductive numbers of this magnitude (Bulut and Kato, 2020;Zhao and Chen, 2020). In Rio de Janeiro, the current effective reproductive number is estimated about 1.44 (Melan et al, 2020).…”