Long COVID – what is it exactly?

The World Health Organization (WHO) published the first official clinical definition of Long COVID on October 6, 2021. Furthermore, a definition for Long COVID in children was issued in February 2023 by the WHO.

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According to the WHO (World Health Organization), a “Post COVID-19 condition” occurs if a person with a probable or confirmed SARS-CoV-2 infection develops symptoms within three months of the infection, these symptoms last for at least two months and cannot be explained by other diagnosis.

According to the WHO, symptoms can reappear after an initial recovery from COVID-19 or simply persist after the original illness. Symptoms can come on in bursts or come back suddenly after what is believed to be healing.

According to the WHO, there may be a specific definition for children.

The WHO definition is in line with previous proposals, for example by NICE or mediX Switzerland, which were also adopted by the Altea Team. The WHO stresses that the definition can change as new information emerges. The organization intends to continue monitoring the situation to identify any changes that could affect the definition. Should factors change, the WHO publishes an updated definition.


There are many terms used to define Long COVID: Post-COVID SyndromePASC (post-acute sequelae of COVID-19) or Long haul COVID. However, the WHO did not want to discuss the name, but instead wanted to focus on the definition of the syndrome. Therefore, WHO kept the term “post COVID-19 condition”, as they had already suggested in September 2020, in the knowledge that those affected are in favor of using the term “Long COVID-19”. Altea will also continue to talk about Long COVID.

Depending on the definition, different deadlines determine whether there are long-term effects. Altea uses the term “Long COVID” if symptoms last longer than 4 weeks, based on the definition of the British NICE, to which the Swiss medical network mediX also refers. Long COVID in this definition is the umbrella term for a prolonged COVID-19 infection and for a syndrome triggered by this infection.

  • Acute infection: up to 4 weeks
  • Prolonged infection: 4-12 weeks
  • Post-COVID syndrome: more than 12 weeks
  • Long COVID: anything from 4 weeks


In contrast to a clearly identifiable disease, a syndrome is a combination of different symptoms, of which it is not yet clear how they are related and what their cause is. It is also possible that Long COVID is several different syndromes, and that some people suffer from a single syndrome, while others from several syndromes contemporarily.

The knowledge about Long COVID is constantly developing due to the research activity.

Altea follows these developments and regularly updates the information to reflect the current state of knowledge.


According to the WHO, the most common symptoms include fatigue (exhaustion), shortness of breath and cognitive impairment (brain fog). In addition, those affected by Long COVID report other symptoms. Based on a survey, Altea has currently grouped the various symptoms into 14 clusters. You can find a description of all symptom clusters as well as tips and support for coping with the symptoms in everyday life in the Altea Guidebook.

Who is affected?

Long COVID can affect anyone, not just members of risk groups or patients with a severe course of the disease. Also young, healthy people with a mild COVID-19 disease and even children can suddenly be affected by sometimes serious and long-lasting symptoms after surviving the infection. For hospitalized people, however, the risk of Long COVID seems to be significantly higher.

According to the FOPH (Federal Office of Public Health), the following findings were available in January 2023:

  • Around 20% of adults with a confirmed SARS-CoV-2 infection are suffering long-term effects three months after their infection. In non-hospitalized adults the median estimate for the Long COVID prevalence is 12%.
  • The Long COVID prevalence among all infected persons is estimated at 5%.
  • Around one in three people who have had a severe case, and around one in six who have had a mild or asymptomatic case, are affected by long-term effects.
  • Around 2-3% of children and young people who contract the coronavirus suffer long-term effects.
  • It has been reported that women suffer more frequently from long term effects of COVID-19 as men. There is no robust evidence on the role of sex in the severity of Long COVID disease. (FOPH, version 24.01.2023) 
Long COVID - what can I do?

Long COVID - what can I do?

In the Altea Guidebooks we have put together tested tips for various symptoms. These are continuously updated and expanded. It is worth checking in regularly!

Where can I get help?

In our Directory you will find clinics, doctors and therapists with Long COVID offers - sortable by symptom, canton and place of residence.

I want to exchange ideas

Altea lives from exchange. That is why we have set up a forum in which those affected, relatives, doctors and researchers can exchange ideas. Take part too!