A harmonised approach to Long COVID in the EU is desirable: the currently wide range of definitions and guidelines hamper effective response to the condition

Defining the condition Long COVID – also called post-COVID – is a challenge, especially because of the wide range of symptoms associated with it. Lack of a clear definition of Long COVID makes it hard to develop effective guidelines for the treatment of patients and surveillance of the condition. Given the current variability in definitions and the voluntary participation of patients in existing registries in the EU Member States, there are no good estimates of the total number of patients and the severity of their condition. These are the main findings from an exploratory study carried out by Nivel on behalf of the European Commission. Harmonisation is desirable in order to obtain consistent data on Long COVID and its treatment.

After a COVID-19 infection, about 36 million people in the WHO European Region show persistent symptoms of the condition, which is also known as ‘Long COVID’ or ‘post-COVID’. In 2023, the European Commission established the Network of Expertise on Long COVID (NELC), to achieve a uniform and effective response to Long COVID by means of EU-wide collaboration. The EUHealthSupport Consortium, led by Nivel, has carried out a mapping study to support the work of the NELC.

Definitions used for Long COVID often in accordance with those used by WHO or NICE

In 33 of the 34 selected EU countries, we found definitions of Long COVID in use. Most of these definitions were consistent with those used by the World Health Organization (WHO) or the National Institute for Health and Care Excellence (NICE). A distinction is made between definitions that referred to the duration of symptoms and those that did not. Key elements of the definitions found include time criteria, persistence of symptoms, exclusion of alternative diagnoses and inclusion of a broad range of symptoms. Definitions varied in several ways: impact on daily life, organ system involvement, severity of initial acute COVID-19 infection and naming conventions.

Long COVID guidelines for diagnosis and treatment available for various disciplines

In 21 of the 34 selected countries, guidelines were found to diagnose and manage Long COVID. Common elements included the advocacy of a multidisciplinary approach, a central role for primary care and a focus on rehabilitation. Some guidelines included recommendations for referral to specialised care and follow-up procedures. The guidelines differed in their target group: they were aimed at healthcare providers in general, at secondary (specialised) care providers, at policy makers or at interdisciplinary support by municipalities. The guidelines also showed some differences in addressing the specific symptoms and organ systems possibly affected by Long COVID.

Long COVID surveillance is being developed in a number of EU countries

In mapping current Long COVID surveillance systems, we found nine Long COVID registries; in Australia, Germany, Spain, Sweden, the Netherlands, Germany, the Czech Republic, New Zealand and the United States. In some countries – including Bulgaria, Italy, Germany and Ireland – there are clinical centres for Long COVID patients from which data are collected; this serves as an alternative source of information on the Long COVID population. In addition, several countries are conducting cohort studies on Long COVID patients. As there is no uniform way to define and register Long COVID, the possibilities to arrive at consistent figures are limited, as well as the opportunity to gain insights on how Long COVID develops over time. This underlines the importance of promptly arriving at a uniform definition.

About the study

The mapping study was conducted to provide insight into the current state of affairs regarding three aspects of Long COVID: Long COVID definitions; Long COVID guidelines and knowledge on diagnosis and treatment; Long COVID surveillance systems in EU Member States and beyond. Nivel conducted the study within the EUHealthSupport Consortium, in collaboration with the University of Groningen in the Netherlands. The research was part of the scientific support of the ‘Network of Expertise on Long COVID (NELC)’ of the European Commission.

The study was funded by the European Health and Digital Executive Agency (HaDEA) on behalf of the Directorate-General for Health and Food Safety (DG SANTE).