Published: 30 September 2021
New research supported by the NIHR has shown that 37% of people who experienced COVID-19 had at least one long COVID symptom in the 3-6 month period after infection.
The large study reveals the scale of long COVID, with symptoms affected by sex, age and severity of infection. The most common symptoms were breathing problems, abdominal symptoms, fatigue, pain and anxiety/depression.
Researchers at the NIHR Oxford Health Biomedical Research Centre investigated long COVID in over 270,000 people recovering from COVID-19 infection, using data from the US-based TriNetX electronic health record network. The study reports on how commonly nine core long COVID symptoms were diagnosed, and how this rate compared to people recovering from influenza.
The nine core long COVID symptoms reported 90-180 days after COVID-19 was diagnosed were:
- Anxiety/depression – 15%
- Abnormal breathing – 8%
- Abdominal symptoms – 8%
- Other pain – 7%
- Fatigue – 6%
- Chest/throat pain – 6%
- Headache – 5%
- Cognitive problems (‘brain fog’) – 4%
- Myalgia (muscle pain) – 1.5%
- Any of the above features – 37%
The findings show that severity of infection, age, and sex affected the likelihood of long COVID symptoms: long COVID symptoms were more frequent in those who had been hospitalised, and they were slightly more common in men than women.
These factors also influenced which of the symptoms people were most likely to experience. For example, older people and men were more likely to have breathing difficulties and cognitive problems, whereas young people and women had more headaches, abdominal symptoms and anxiety/depression.
Many patients had more than one long COVID symptom, and symptoms tended to co-occur more as time progressed.
The study, published in the journal PLOS Medicine, also looked at the same symptoms in people recovering from influenza. Long COVID symptoms did occur after influenza, but were 1.5 times more common after COVID-19.
Dr Max Taquet, NIHR Academic Clinical Fellow at the University of Oxford, who led the analyses, said: “The results confirm that a significant proportion of people, of all ages, can be affected by a range of symptoms and difficulties in the 6 months after COVID-19 infection. These data complement findings from self-report surveys, and show that clinicians are diagnosing patients with these symptoms. We need appropriately configured services to deal with the current and future clinical need.”
Professor Paul Harrison, who headed the study in the Department of Psychiatry at University of Oxford, said: “Research of different kinds is urgently needed to understand why not everyone recovers rapidly and fully from COVID-19. We need to identify the mechanisms underlying the diverse symptoms that can affect survivors. This information will be essential if the long-term health consequences of COVID-19 are to be prevented or treated effectively.”
This study does not explain what causes long COVID symptoms, nor how severe they are or how long they will last. The results do not take into account people who had COVID-19, but were not diagnosed, e.g. because they were asymptomatic and did not get tested, nor COVID-19 survivors with long COVID symptoms that had not been recorded in their health records.
- Learn more about the NIHR’s research into the long term impact of COVID.