[The outbreak of COVID-19 in China]. / Der Ausbruch von COVID-19 in China.

The transmission dynamics of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in Wuhan and Hubei Province differ considerably from those in the rest of China. In Hubei province SARS-CoV­2 led to a dramatic outbreak. Intensive control measures (travel restrictions, isolation of cases, quarantine of contacts and others) led to the control of the outbreak. Despite travel restrictions SARS-CoV­2 was detected in other provinces in the following weeks. Consistent and intensive identification and isolation of infected persons ("containment") was able to prevent an outbreak outside Hubei province, providing an example for the control of SARS-CoV­2.

[Epidemiology of SARS-CoV-2 infection and COVID-19]. / Epidemiologie von SARS-CoV-2-Infektion und COVID-19.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a new ß­Coronavirus that was first detected in 2019 in Wuhan, China. In the ensuing months it has been transmitted worldwide. Here the authors present the current knowledge on the epidemiology of this virus. SARS-CoV­2 replicates mainly in the upper and lower respiratory tract and is primarily transmitted by droplets from asymptomatic and symptomatic infected subjects. The estimate for the basic reproduction number (R) is currently between 2 and 3, while the incubation period is 6 (median, range 2-14) days. Although most infections are uncomplicated, 5-10% of cases develop pneumonia, which can lead to hospitalization, respiratory failure and multiorgan failure. Risk factors for a complicated disease course include age, hypertension, chronic cardiovascular and pulmonary disease and immunodeficiency. The overall case fatality rate is 1.4%, with the rate rising in the sixth decade of life. Nosocomial and infections in medical personnel have been reported. Drastic reductions in social contact have been implemented in many countries with outbreaks of SARS-CoV­2, leading to rapid reductions in R. Which of the measures have been effective is still unknown.

[Epidemiology of SARS-CoV-2/COVID-19]. / Epidemiologie von SARS-CoV-2/COVID 19: Aktueller Stand.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is a beta coronavirus, which first appeared in 2019 and rapidly spread causing a worldwide pandemic. Here we present a nonsystematic review of the current knowledge on its epidemiological features. The SARS-CoV­2 replicates mainly in the upper and lower respiratory tract and is mainly transmitted by droplets and aerosols from asymptomatic and symptomatic infected subjects. The estimate for the basic reproduction number (R0) is between 2 and 3 and the median incubation period is 6 days (range 2-14 days). Similar to the related coronaviruses SARS and Middle East respiratory syndrome (MERS), superspreading events play an important role in spreading the disease. The majority of infections run an uncomplicated course but 5-10% of those infected develop pneumonia or a systemic inflammation leading to hospitalization, respiratory and potentially multiorgan failure. The most important risk factors for a complicated disease course are age, hypertension, diabetes, chronic cardiovascular and pulmonary diseases and immunodeficiency. The current infection fatality rate over all age groups is between 0.5% and 1% and the rate rises after the sixth decade of life. Nosocomial transmission and infections in medical personnel have been reported. A drastic reduction of social contacts has been implemented in many countries with outbreaks of SARS-CoV­2, leading to rapid reductions in R0. Most interventions have used bundles and which of the measures have been more effective is still unknown. Using mathematical models an incidence of 0.4%-1.8% can be estimated for the first wave in Germany.