COVID-19 (coronavirus disease 2019)

COVID-19 is caused by the SARS-CoV-2 coronavirus. The disease commonly produces respiratory symptoms. Both mild and severe forms are possible, as are long-term consequences. People can get vaccinated against COVID-19. Various types of medication are also available to treat the illness.

At a glance

  • COVID-19 is an infectious disease caused by the SARS-CoV-2 coronavirus.
  • High temperature, cough, rhinitis (sneezing, itchiness and a blocked or runny nose) are common symptoms, as are a sore throat, headache and achy limbs.
  • COVID-19 infections are usually mild and people can generally recover at home.
  • However, severe cases and long-term effects are possible. Older people and people with pre-existing conditions are particularly at risk.
  • Vaccination offers protection against severe forms of the disease. There are also various types of medication to alleviate symptoms.
  • Certain hygiene and other precautionary measure help reduce the risk of infection.

Note: The information in this article cannot and should not replace a medical consultation and must not be used for self-diagnosis or treatment.

An older woman with a surgical mask

What is COVID-19?

COVID-19 disease is caused by an infection with the SARS-CoV‑2 coronavirus. As its name indicates, it is related to the pathogen that causes severe acute respiratory syndrome (SARS)

Some people who become infected with COVID-19 do not develop any symptoms. Most people who are infected have a mild or moderate form of the disease. Some develop such a severe form that they have to be hospitalized. COVID-19 is fatal for some people. The cause of death is usually lung or multiple organ failure. 

Older people and people with pre-existing conditions are particularly at risk of becoming seriously ill with COVID-19. However, this can also happen to young and otherwise healthy people. 

COVID-19 vaccines help prevent severe illness and death.

What are infectious diseases?

The video below looks at when doctors talk about an infectious disease, which pathogens trigger infectious diseases, and how they are transmitted.

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What are the symptoms of COVID-19?

With COVID-19, the first symptoms appear around 3 days on average following infection. However, symptoms may also occur somewhat sooner or later than this.

With COVID-19, the first symptoms appear around 3 days on average following infection.

Common symptoms are:

  • coughing
  • high temperature
  • rhinitis (sneezing, itchiness and a blocked or runny nose)
  • sore throat
  • headache and limb pain

Other possible symptoms are:

  • lost or changed sense of smell and taste
  • shortness of breath that can reach the point of respiratory distress (difficulty breathing)
  • abdominal pain
  • nausea, vomiting
  • diarrhea
  • loss of appetite
  • skin rash, conjunctivitis
  • swollen lymph nodes
  • sleepiness

What should people do if they have symptoms?

Stay at home until the symptoms have significantly improved. Avoid contact with others, especially people in high-risk groups and observe physical distancing and hygiene rules. Phone your family doctor for advice about what to do next. Outside of consulting hours, you can contact the non-emergency medical assistance service by phoning 116117.

Important: If your symptoms get worse, seek medical assistance immediately. Call the emergency number 112 if you experience symptoms like respiratory distress or breathlessness.

How long do people with COVID-19 remain infectious?

People infected with SARS-CoV-2 can transmit the virus to others 1 to 2 days before they experience any symptoms. The risk is greatest around the onset of symptoms.

How long someone stays infectious depends on the form the disease takes. Most people are no longer infectious after 10 days but longer infectious periods are possible in some cases.

Floating virus particles

How do people become infected with COVID-19?

The SARS-CoV-2 coronavirus is primarily spread by droplets that are released by infected people when they cough, sneeze, breathe, speak and sing.

Depending on the size and properties of these droplets, they are classified as larger droplets or as aerosols, which are tiny microdroplets suspended in the air.

Aerosols are created by people when they breathe or speak, but particularly when they shout loudly, sing or engage in sports activities. A significantly greater number of larger droplets are produced when people cough and sneeze.

While larger droplets sink to the ground faster, aerosols may remain suspended in the air for longer periods and spread within enclosed spaces.

If droplets containing the virus come into contact with the mucous membranes in other peoples’ noses, mouths or eyes, they may become infected with the virus. The virus may also be transferred to the mucous membranes if the droplets land on people’s hands and they then touch their face with their hands (this is known as “smear infection”, i.e., infection by touch).

Important: SARS-CoV-2 is capable of changing its properties. By now, there are several variants in existence that spread faster and are more transmissible than the original virus.

How dangerous are the virus variants?

In general, infections with the Omicron virus variant tend to be less severe than infections with previous variants – especially in people who have been vaccinated. It is impossible to predict how the virus will continue to develop and what properties future variants will have. Experts are monitoring developments and re-assessing the situation on an ongoing basis.

More detailed information about virus variants in Germany can be found on the Robert Koch Institute (RKI) website.

Which factors increase the likelihood of developing a severe form of COVID-19?

The likelihood of becoming very ill with COVID-19 increases from the age of 50 to 60 and upwards.

Certain underlying conditions also increase the risk. These include, for example:

People who are obese, smokers and those with Down syndrome are also more likely to develop a severe form of COVID‑19.

In addition, certain medications that weaken the immune system increase the risk of developing a severe case of the illness. These include chemotherapy drugs, for example.

How does COVID-19 progress?

The progression of COVID-19 differs between individuals, depending on how effective the body’s immune system is against the virus.

Most people who are infected don’t become seriously ill and recover within a period of one to two weeks. The symptoms get worse in some people, often from the second week of the illness.

Another possible complication is pneumonia. At this stage, not enough oxygen is entering the bloodstream. Most people with COVID-19 who develop pneumonia require treatment in hospital, in some cases in an intensive care unit.

In rare cases, the disease is fatal. This is more common among older people – most of those who have died as a result of a SARS-CoV-2 infection were over 70 years of age.

What complications can occur with COVID-19?

Complications are also possible, for example, if the SARS-CoV‑2 infection causes pneumonia or if inflammatory processes in the body activate blood clotting.

If an excessive immune response is activated throughout the body, this can damage the lungs and cause severe respiratory problems. The infection can spread to organs such as the heart, nervous system or kidneys.

A strong inflammatory response can cause individual organs to fail. The affected organs then require mechanical support in order to continue functioning. If several organs fail at the same time, this is usually a life-threatening situation.

If increasing numbers of blood clots begin to form, this increases the risk of blood vessels becoming blocked and cutting off the blood supply – which can lead to a pulmonary embolism or stroke.

A secondary bacterial or fungal infection may also occur. These are referred to by medical professionals as superinfections.

What are the long-term effects of COVID-19?

People who become ill with COVID-19 may continue to have health problems for weeks or even months after the acute infection has resolved. If symptoms persist for more than four weeks or if new symptoms develop that cannot be explained in any other way, this is known as “long COVID”. If symptoms last for more than 12 weeks, this is referred to as “post COVID-19 condition”.

The most common symptoms include fatigue and loss of stamina, shortness of breath and concentration and memory deficits, also referred to as “brain fog”.

The probability that health problems will remain over the long term is greater when the COVID-19 infection is severe. But long-term consequences are also possible even when the illness is mild or moderate.

Detailed information about the long-term effects of an infection with SARS-CoV-2 is provided in the article on Long COVID.

How can COVID-19 be prevented?

Various measures can be taken to reduce the risk of infection. COVID-19 vaccination reduces the risk of developing a severe form of the virus.

COVID-19 can be avoided by observing the rules on distancing and hygiene, wearing a mask over the mouth and nose, ventilating on a regular basis, (self-)testing, getting vaccinated and using the coronavirus alert app.

COVID-19 vaccination

Several COVID-19 vaccines are available in Germany, which offer safe and effective protection against a severe form of the virus. Vaccines continue to be developed on an ongoing basis in order to ensure protection against new virus variants. These adapted (i.e., updated) vaccines are also available. They are used in particular for booster vaccinations.

The specific vaccination schedule used depends on:

  • which vaccine is being administered
  • the individual’s age and health status
  • how many vaccinations they have previously received
  • whether and how often they have been infected with the virus

More detailed information about vaccination against COVID-19 is available on – a website operated by the Federal Ministry of Health (Bundesministerium für Gesundheit, BMG).

The website of the Robert Koch Institute (RKI) provides answers to frequently asked questions about COVID-19 and vaccinations.

For more information about COVID-19 vaccines, for example, about their development and the approval process, visit the website of the Paul Ehrlich Institute (PEI).

Hygiene and other precautionary measures

  • Keep your distance – greater distance between people means that viral droplets are more likely to fall onto the ground before they reach another person.
  • Maintain good hygiene – wash your hands regularly with soap; cough and sneeze into a tissue or into the crook of your elbow.
  • Wear a mask – it makes sense to wear a medical face mask covering the mouth and nose in situations where it is difficult to keep a safe distance from others.
  • Ventilate regularly – ensuring an adequate supply of fresh air by opening windows fully on a regular basis is an effective way to remove aerosols from indoor air. Creating a cross-draft between two open windows is the most effective type of ventilation.
  • Take a test – in certain situations, it is useful to take a COVID test in order to protect others, for example, before visiting relatives in hospital or care facilities or prior to having contact with people in at-risk groups.
  • Use the app – the coronavirus alert app available in Germany helps to record daily contact with people who are at risk. A green tile indicates “low risk”, while a red tile means “increased risk”.

For more information about hygiene rules and other precautionary measures – also known as the hands, face, space (AHA) and ventilation and app (L+A) rules – see, a website operated by the Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung, BZgA).

Information about measures to improve infection control in care settings is provided by the Center for Quality in Care (Zentrum für Qualität in der Pflege, ZQP).

Detailed information about the coronavirus alert app and what to do if the app shows a red tile is available from the Robert Koch Institute (RKI) at

How is COVID-19 diagnosed?

COVID-19 symptoms are similar to those of a flu or cold. This means that the disease cannot be diagnosed on the basis of symptoms alone.

It is therefore important to detect the SARS-CoV-2 pathogen. Doctors do this by taking a swab sample from the back of the nose and throat. Samples are sent to a lab, where a PCR test can detect the virus’s genetic material. The result is usually available within 24 hours.

In addition to the laboratory tests, rapid lateral flow tests (rapid antigen tests) are used by trained personnel for on-site detection of an infection. These rapid tests offer the advantage of delivering a result within a period of 15 to 30 minutes. The drawback is that the result is less reliable than the result of a PCR test.

Anyone who has a positive rapid test result should have it confirmed with a laboratory test. If a person has symptoms but the rapid test is negative, a laboratory test is the only way to exclude a SARS-CoV‑2 infection. The same applies to the rapid self tests that can be purchased without a prescription and administered at home.

Answers to frequently asked questions about the various COVID tests – such as when they should be used and how to get a free test – are provided on the website operated by the Federal Ministry of Health (BMG).

Detailed information about how to use rapid self-tests is provided by the Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung, BZgA).

How is COVID-19 treated?

People can recover at home from a mild case of COVID-19. It is important to take plenty of rest and ensure a sufficient intake of fluids. Medication such as paracetamol or ibuprofen may help if the person is suffering from headache or achy limbs.

Which types of medication alleviate the symptoms of COVID-19?

If an individual is at an increased risk of developing a severe infection, doctors may use drugs to treat a mild infection or an infection without symptoms in order to prevent the virus from spreading through the body. These include:

  • nirmatrelvir/ritonavir (Paxlovid)
  • remdesivir (Veklury)
  • molnupiravir (Lagevrio)

The precise anti-viral drug used depends for example on individual factors, such as whether:

  • the patient has other underlying conditions
  • the patient is taking any long-term medication
  • there are any possible contraindications

Important: To benefit from anti-viral treatment, the drug must be taken as soon as possible after symptoms are first noticed or after the point in time at which it is suspected the person became infected.

What other therapies are available?

People who require oxygen or mechanical ventilation due to developing pneumonia as a result of COVID-19 are given anti-inflammatory medication, usually dexamethasone. One important measure in treating a COVID-19 patient who is being ventilated is to lie them on their stomach.

Patients with an increased risk of developing blood clots (thromboses) are given anticoagulants (anti-clotting medication) such as heparin where possible. Further treatment depends on the possible complications that may occur. If the patient develops a secondary bacterial infection, for example, they are given antibiotics.

How does ventilation work?

To support the patient’s breathing, doctors first administer oxygen, for example, via a nasal cannula or a respiratory mask.

If the lungs fail so that independent breathing is no longer possible, mechanical ventilation is required. For this purpose, doctors insert a breathing tube into the lungs under anesthetic.

If this is not sufficient, the use of ECMO (extracorporeal membrane oxygenation) may be necessary. This treatment is commonly known as “artificial lungs”. It involves pumping the blood out of the body, adding oxygen to it and then pumping it back into the body.

Where can I find more information about COVID-19?

For detailed information about COVID-19 in Germany, COVID-19 in children and COVID-19 during pregnancy and breastfeeding, see – a website operated by the Federal Ministry for Health (Bundesgesundheitsministerium, BMG). 

The website of the Robert Koch Institute (RKI) provides answers to frequently asked questions about SARS-CoV-2 and COVID-19.

Information about COVID-19 is provided by – a website operated by the Federal Center for Health Education (Bundeszentrale für gesundheitliche Aufklärung, BZgA).

In cooperation with the Robert Koch Institute (RKI).

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