Everyone can develop Long COVID

Lifelines is a large continuous cohort study that has run in Groningen, Friesland and Drenthe since 2006. More than 167,000 people from the general population take part in it. To discover more about COVID-19, we began to follow the symptoms of about 76,000 people from this cohort since the end of March 2020, when the pandemic started. A large proportion of them subsequently caught COVID-19. In this group, we can clearly distinguish how possible symptoms that persist after 3 to 5 months relate to the symptoms people experienced before COVID-19. Are the symptoms new or an exacerbation of pre-existing symptoms? We compare these symptoms with those of cohort participants who did not suffer from COVID-19.

During a pandemic, a pre-existing cohort can offer many benefits as an entire research infrastructure is already in place. Well before COVID-19, we had already collected biomedical data from these people, such as a lung function test and an ECG and we have samples of their biomaterial in the freezer. From questionnaires, we had already established their quality of life over many years.

We have measured ten symptoms that are possibly associated with Long COVID, such as chest pain, difficulty breathing, muscle ache, loss of taste and smell, tingling in the hands or feet, and fatigue. In addition, we also measured symptoms that fit the clinical picture of Long COVID, but which were not measured from the start of the study, such as cognitive functions and brain fog. In retrospect, that is both a shame and a missed opportunity.

For our study, we again invited people to visit our outpatient research clinic: those with Long COVID, those who recovered from COVID-19, and those who did not get COVID-19. In addition, we again collected samples of biomaterial from them and examined whether there were indications for organ damage or immunological abnormalities. We performed one-off extra measurements on some of the people who suffered COVID-19, such as a HUT (head upright tilt table) test and an exertion test. Now, we can compare all of these data with the data that we collected earlier. That allows us to investigate, for example, which possible mechanisms play a role in the development of Long COVID.

We first analysed the infections that occurred until the end of April 2021. This group with COVID-19 was infected with the original variant and the Alpha variant. Vaccinations were still barely available, so most of the population remained unvaccinated. Our measurements revealed that 21.4% of these people with COVID-19 satisfy the criteria for Long COVID. However, in the group of people without COVID-19, new or exacerbated symptoms were experienced by 8.7% as well. If you correct for this, then only 12.7% of the patients satisfy the criteria for Long COVID. That is one in eight patients. The severity of the symptoms also varied. We have published the results in The Lancet.

The second analysis concerns symptom profiles: can you find clusters of people with different risk factors and what are those risk factors? We know that women have a higher risk of developing Long COVID, as equally people with certain chronic illnesses or people who have experienced an acute severe illness. We also examine to what extent people with Long COVID can still function. For example, a loss of smell is very annoying but you can nevertheless continue to go to work unless you are a chef, of course. Only a small percentage of the examined people can no longer work. ‘That still concerns quite a large group, however, since such a large number of people have had COVID-19.

Persistent symptoms after infections are nothing new. When I was at secondary school, the kissing disease was infamous: glandular fever caused by the Epstein-Barr virus. Most young people did not become ill but there was always somebody who had to spend months in bed. Post-infectious syndromes carry a stigma. Patients often hear: ‘Pull yourself together. You just need to exercise more.’ Since the COVID-19 pandemic, however, something has changed. Doctors now also dare to publicly discuss their own experience with long-term symptoms. That sheds new light on the patient population. So get rid of all your preconceptions, as it could just as easily have been you. This is a very positive development.