Incubation period

The incubation period also differs depending on the subspecies of coronavirus. Usually it is 5-7 days. However, cases of 2 weeks of incubation or shorter times have also been documented.

Duration of illness

The duration of the disease has not yet been conclusively clarified. The symptoms can last for a week or longer, but if there are no symptoms, a minimal excretion of the pathogen must still be assumed. The Robert Koch Institute has drawn up some guidelines for isolation in patients already diagnosed. In these guidelines, it is recommended that isolation be lifted at the earliest 10 days after the onset of symptoms if certain criteria such as freedom from fever for 48 hours have been met.

Causes

The cause of the infection is the transmission of the virus. Depending on the strength of the immune system and the viral load, the body deals with it differently. The transmission occurs primarily from animal to human, also called zoonosis.

A further transmission from person to person is possible by smear and droplet infection. The symptoms are caused by binding to specific host cells. The binding structures of the individual types of coronavirus differ.

For example, the novel cornavirus and the SARS virus bind to exopeptidases. In contrast, the MERS virus binds to the DPP-4 receptor in order to enter the host cell. It is assumed that this specific receptor is only found in the bronchial tubes and kidneys, which is why MERS can lead to kidney failure.

There are a large number of coronaviruses. The novel corona virus was probably transmitted by bats, possibly over a number of other animals that were also infected with the virus. It is believed that the first contact with humans was at a market in the Chinese city of Wuhan.

Viruses often mutate, sometimes creating new characteristics. For example, the novel corona virus is more infectious than the other viruses in its group and is therefore transmitted more quickly. A prolonged survival time outside the host, for example on contaminated surfaces, is being discussed, among other things.

Diagnostics

The diagnosis is confirmed by laboratory tests. These are carried out if symptoms exist or contact with infected persons is known. A so-called PCR is carried out to detect the RNA, i.e. genes of the virus, in the blood or the coughing sputum.

Imaging such as X-rays can also be helpful to detect an inflammation of the lungs. Depending on the laboratory, a virus infection can be detected by PCR (polymerase chain reaction) from a sample within a few hours. If the test is carried out in a practice, the transport of the samples is important for how quickly the result is available.

This can take several days. The samples are taken either from the nasopharynx or the deep respiratory tract, e.g. sputum during a productive cough. Since the end of February 2020, the health insurance companies have largely covered the test.