SARS-CoV-2 infection / COVID-19

The incubation period is usually three to seven, maximally 14 days. The symptoms and severity of SARS-CoV-2 infection can vary significantly. The most common symptoms encompass fever, coughing, breathing difficulties and fatigue. Therefore, in the majority of patients, the infection resembles a cold with light fever, with irregular lung infiltrates. Some patients, especially older and chronically ill persons, develop severe acute respiratory distress syndrome.
Suitable methods for the diagnosis of SARS-CoV-2 infections are the detection of viral RNA by reverse transcriptase polymerase chain reaction (RT-PCR) or of virus protein by means primarily in sample material from the upper (nasopharyngeal or oropharyngeal swab) or lower respiratory tract (bronchoalveolar lavage fluid, tracheal secretion, sputum, etc.). PCR allows detection of the pathogen even in subclinical or asymptomatic courses in a few days after virus contact and up to 14 days after onset of possible symptoms. Moreover, the combination of different parameters in an RT-PCR allows detecting and differentiating SARS-CoV-2 and other respiratory pathogens such as influenza viruses in one test.

The determination of antibodies enables confirmation of SARS-CoV-2 infection in patients with typical symptoms and in suspected cases. It also contributes to monitoring and outbreak control. For significant serological results, two patient samples should be investigated, one from the acute phase (week 1 of the illness) and one from the convalescent phase (3 to 4 weeks later).