Long-term symptoms after COVID-19 ("long COVID")
Most people who have COVID-19 recover, but some may develop long-term medical problems. Patients with a severe disease course who receive intensive care have an increased risk of developing long-term symptoms (sequelae) after COVID-19 (known as "long COVID").
What are the long-term symptoms of COVID-19?
For most people, COVID-19 is a mild illness that passes, but some experience symptoms that last beyond the acute phase. People who have symptoms that affect their daily life and have lasted for at least 2 months, are diagnosed with "Post-COVID-19 condition". The diagnosis is usually made 3 months after the patient has had the disease.
Such long-term symptoms have also been reported after many other infections, and it is therefore not unexpected that some people will experience long-term problems after COVID-19. We already know that patients who are treated for severe lung failure in intensive care, regardless of the cause, can struggle with long-term problems after being discharged from hospital.
About the diagnosis "Post COVID-19 condition"
The term "long COVID" was already in use in May 2020 in patient stories in social media. In autumn 2020, the World Health Organization (WHO) established the diagnosis "Post COVID-19 condition", with diagnosis code U09 in ICD-10 for use in hospitals.
The WHO prepared a definition of "Post COVID-19 condition" in October 2021. There are several different definitions and terms for the condition. In autumn 2021, the medical community in Norway agreed to refer to this as "senfølger etter COVID-19" in Norwegian.
COVID-19 can cause general symptoms and symptoms from most organs. The same applies to long-term symptoms after COVID-19. The most commonly reported symptoms 6-12 months after you have having COVID-19 are:
- impaired ability to think and concentrate (so-called "brain fog")
- impaired memory
- altered sense of taste and/or smell
- shortness of breath
- muscle aches
- anxiety and depression
Several of these symptoms are quite common, and during the pandemic some of the symptoms seemed to increase even among people who did not get COVID-19. Nevertheless, most studies show that there is a greater risk of experiencing such symptoms among those who were infected by COVID-19, compared to those who were not infected. The difference in symptoms between infected and non-infected becomes smaller as time goes by, but it is still uncertain how long the symptoms persist among those who experience long-term symptoms after COVID-19.
Risk factors for long-term symptoms
Those who have an increased risk of long-term symptoms of COVID-19, 6-12 months after the disease, are:
- people who have had a more severe COVID-19 disease course and who have been admitted to hospital and intensive care,
- people with multiple symptoms at the time of diagnosis and who have underlying conditions
- middle-aged people
Women are more prone to long-term symptoms than men, regardless of whether they have been admitted to hospital or not.
Knowledge of long-term symptoms
Many studies have now been carried out that have investigated long-term symptoms, including possible risk factors and causal mechanisms. Many of the studies lack a control group which makes it difficult to know whether the symptoms reported by the participants are due to COVID-19 or not. There is a large difference in how often the various symptoms are reported. The differences may be because the studies have used different definitions and methods to map the symptoms, and that they are of differing quality. The fewest studies have examined the severity of the symptoms. It is then difficult to assess whether the reported symptoms affect quality of life and daily function.
Most of the studies are still from the first phase of the pandemic. There have nevertheless been some recent studies that have examined the long-term symptoms of COVID-19. The studies have compared vaccinated with non-vaccinated people, and those who are vaccinated seem to have fewer long-term symptoms than those who are not vaccinated. The studies have also compared those who have been infected by omicron with those who have been infected with other virus variants. Omicron-infected people appear to have a lower risk of long-term symptoms compared to those who have been infected with earlier virus variants.
In addition to studies, several systematic reviews have also been published. The NIPH has prepared four versions of a rapid review of long-term symptoms after COVID-19. The first edition was published in March 2021, the fourth was published in December 2022:
Several ongoing studies are examining the effect of various treatment and rehabilitation measures, both in Norway and internationally. The measures that exist today are based on experience and indirect documentation from similar conditions.
If you have had a mild or moderate COVID-19 disease course, and after four weeks have symptoms that make it difficult to participate in everyday activities, the Directorate of Health recommends that you contact your family doctor. Your doctor will then assess whether there is a need for rehabilitation.
Patients with a severe disease course and lengthy stays in intensive care often have a need for rehabilitation.
- Guidelines from the Norwegian Directorate of Health on long-term sequelae and rehabilitation after COVID-19- In Norwegian