Long covid

Long Covid is a condition caused by SARS-CoV-2 infection in which symptoms persist for more than two months.

Last updated on 22 June 2026

In brief

  • In early 2020, the infectious disease Covid-19, caused by SARS-CoV-2, emerged and rapidly developed into a global pandemic.
  • The pandemic unfolded through successive epidemic waves, leaving some individuals with post-Covid-19 condition, or long Covid, a disorder in which symptoms persist for more than two months.
  • Around two million people in France are estimated to be experiencing long Covid symptoms.

Origin of long covid

History

The SARS-CoV-2 virus, responsible for Covid-19, spread worldwide as a pandemic beginning in early 2020 through several successive waves. In France, the pandemic was characterised by a succession of epidemic waves.¹

From its emergence until March 2023, SARS-CoV-2 caused more than 670 million cases and 6.8 million deaths worldwide, including 39 million cases and more than 150,000 deaths in France.²

As early as the end of the first epidemic wave in May 2020, persistent symptoms lasting for weeks or months after the initial illness were reported, leading to the emergence of the term “long Covid”. This term, proposed by patients themselves, reflects the heterogeneity of the condition and moves beyond the distinction between hospitalised and non-hospitalised patients.³˒⁴

Several definitions of this condition exist.⁴

According to the World Health Organization (WHO)*, which preferentially uses the term “post-Covid-19 condition”, the condition occurs in individuals with a history of probable or confirmed SARS-CoV-2 infection and is characterised by symptoms that persist for at least two months, cannot be explained by an alternative diagnosis, and generally appear within three months of the initial infection. These symptoms may develop following an initial recovery or may persist from the acute illness. They may also fluctuate or relapse over time and generally have an impact on daily functioning.⁵

The United States adopts a broader definition. The term “long Covid” is used to describe “all chronic health conditions occurring after SARS-CoV-2 infection.”⁴ Symptoms must persist for at least three months, regardless of whether they can be explained by another diagnosis or by diseases potentially triggered by SARS-CoV-2 infection, such as diabetes, interstitial lung disease or migraine.⁴

*It should be noted that the WHO officially recognised long Covid on 21 August 2020.⁵

Epidemiology

By the end of 2022, approximately two million people in France were affected by long Covid.⁶

Estimating the number of cases remains challenging because of the different definitions used for the condition.⁷ Another difficulty concerns the distinction between probable and confirmed infections, which complicates attribution of symptoms to SARS-CoV-2. This issue arose during the first epidemic wave when PCR testing was not yet widely available. It also remains relevant during periods of lower viral circulation, when other circulating viruses may produce similar persistent symptoms, and in the context of declining SARS-CoV-2 testing in community settings.

To date, France has published two studies⁶˒⁷ using the WHO definition.⁸ The most recent study, conducted between August and November 2022, reported a prevalence of 4% in the overall adult population⁶˒⁷ and 8% among adults previously infected with SARS-CoV-2.⁷

The prevalence of long Covid in the general population is approximately twice as high among women (5.4%) as among men (2.6%).⁷ This increased risk among women was confirmed in a National Institutes of Health (NIH) study published in 2025, although with somewhat lower estimates.⁹ Severe forms account for approximately 20% of Long Covid cases.¹⁰˒¹¹

The French study also showed that long Covid is more common among individuals hospitalised for Covid-19 (18.6%) than among those who were not hospitalised (7.8%).⁷ However, prolonged symptoms following Covid-19 may also occur in individuals who initially experienced only mild disease.³

Anyone can develop long Covid, although several factors appear to increase the risk.⁸˒¹⁰

The main risk factors associated with the development of long Covid, ranked according to the strength of evidence, are:⁸˒¹²⁻¹⁶

  • Pre-existing comorbidities (+++)
  • Female sex (+++)
  • Social disadvantage or socioeconomic deprivation (++)
  • Hospitalisation during acute infection (++)
  • Numerous and/or severe acute symptoms (++)
  • Lack of vaccination or incomplete vaccination (++)
  • Possible insufficient rest during recovery (+)
  • Absence of antiviral treatment during the acute phase (+)
  • Multiple reinfections (+)
  • Older age (+/-)

Long Covid in children

With prevalence estimates ranging from 1% to 27% depending on follow-up duration, the true prevalence of paediatric long Covid remains uncertain.¹⁷⁻²⁰ These differences reflect variations in case definitions, methodologies and study populations.²¹ Nevertheless, paediatric Long Covid is a genuine condition that affects a significant, though likely underestimated, number of children and adolescents. Persistent symptoms can have long-term consequences for young people, preventing them from attending school regularly or maintaining normal social activities.¹⁸

The severity and number of symptoms during the acute phase, female sex, age (adolescents and young adults), and comorbidities such as asthma, obesity and allergic conditions appear to be associated with Long Covid.¹⁸˒²⁰ The predominance of fatigue, gastrointestinal symptoms, musculoskeletal pain and cognitive impairment varies according to age.²⁰ Although its full social impact remains to be determined, emerging evidence suggests a concerning effect on educational attainment and social and emotional development.²¹⁻²⁴

Symptoms and pathophysiology

Symptoms

Symptoms vary considerably between individuals, as well as between adults and children.

Overall, the most frequently reported symptoms are:⁸

  • Severe fatigue
  • Shortness of breath or breathing difficulties
  • Memory, concentration or sleep disturbances
  • Persistent cough
  • Chest pain
  • Speech difficulties
  • Muscle pain
  • Loss of smell or taste
  • Depression or anxiety
  • Fever

People living with long Covid may experience substantial difficulties in everyday functioning. The condition can significantly affect their ability to carry out routine daily activities.⁸

Pathophysiology

Long Covid appears to be a complex and multifactorial syndrome. Several mechanisms have attracted particular attention:²⁵

  • Viral persistence: actively replicating virus or persistent viral proteins may continue to exert harmful effects either directly or by stimulating an ongoing inflammatory response. The persistence of these elements appears to be associated with long Covid during the first months following infection, although this association seems to diminish over time. Viral components have been detected in tissues several months after infection.²⁶˒²⁷
  • Immune dysregulation: following SARS-CoV-2 infection, the immune response may become excessive or persist independently of the initial infection. Studies supporting this hypothesis have shown that individuals with long Covid may exhibit higher levels of inflammation-related proteins and altered responses in certain white blood cell populations compared with individuals who recovered from Covid-19 without persistent symptoms.
  • Autoimmunity: molecular mimicry* or prolonged immune activation may lead to the production of autoantibodies initially directed against SARS-CoV-2 but capable of damaging host tissues, thereby sustaining inflammation even after viral clearance.²⁵˒²⁹
  • Endothelial dysfunction and microvascular damage: these may occur during the acute phase and/or be maintained by inflammatory mechanisms.
  • Mitochondrial dysfunction: resulting in impaired cellular energy metabolism.
  • Dysbiosis: alterations in the gut microbiota may have multisystem consequences and contribute in particular to fatigue and breathlessness.
  • Reactivation of latent viruses: such as Epstein–Barr virus (EBV) and cytomegalovirus (CMV), which may contribute to persistent fatigue.
  • Cell death: the virus itself, or the inflammatory response it triggers, may have caused long-lasting tissue damage. Persistent symptoms may therefore result from incomplete tissue repair.

These mechanisms continue to be investigated. None of these hypotheses excludes the others. Indeed, several mechanisms may coexist, and symptoms may result from direct or indirect damage affecting one or more organs. For example, a given organ may simultaneously be affected by endothelial dysfunction and the action of autoantibodies. Similarly, involvement of the nervous system alone could explain a wide range of symptoms. This is supported by functional imaging studies and MRI findings showing multiple cerebral abnormalities** that may contribute to cognitive symptoms such as memory and concentration difficulties.

Brain positron emission tomography (PET) imaging has demonstrated reduced resting glucose metabolism in individuals with Long Covid, further supporting central nervous system involvement.³⁰

Disorders affecting the autonomic nervous system may contribute to more “peripheral” symptoms, including breathlessness, gastrointestinal disturbances and cardiac symptoms.

Animal studies investigating disease mechanisms also suggest that SARS-CoV-2 may be capable of neuroinvasion.

* Molecular mimicry is one of the principal mechanisms through which infectious agents may induce autoimmunity. It occurs when similarities between foreign peptides and host peptides promote the activation of autoreactive T or B cells by a foreign antigen in susceptible individuals.²⁸ In the context of long Covid, molecular mimicry may occur between SARS-CoV-2 proteins and epitopes expressed by cells in the intestine, kidneys, lungs, heart and brain.²⁹

** Autopsy studies have demonstrated brain involvement in humans.

Diagnosis

In France, the French National Authority for Health (HAS) has defined three criteria for identifying individuals with long Covid:³

  • An initial symptomatic episode of Covid-19:
    • Either confirmed by at least one of the following: Positive SARS-CoV-2 PCR test, positive SARS-CoV-2 antigen test, positive SARS-CoV-2 serology, sudden-onset prolonged loss of smell (anosmia) and/or taste (ageusia), typical chest CT findings (bilateral ground-glass pneumonia, etc.)
    • Either considered probable based on the sudden onset of at least three of the following symptoms during an epidemic period: fever, headache, fatigue, myalgia, dyspnoea, cough, chest pain, diarrhoea, pain on swallowing (odynophagia). Positive SARS-CoV-2 serology may support this diagnosis.
  • Persistence of at least one initial symptom for more than four weeks after the onset of the acute phase
  • Persistent symptoms that cannot be explained by another diagnosis unrelated to Covid-19
Sample collection for diagnostic testing
PCR testing for coronavirus detection

Patient management

At present, no specific treatment has been demonstrated to result in complete recovery. Clinical trials showing sustained, although partial, improvements have focused on:

  • Rehabilitation pathways, including multidisciplinary care combining physical rehabilitation and psychological support.³¹˒³²
  • Dysbiosis and treatment with probiotics: one trial involving individuals with long Covid, most of whom had gastrointestinal symptoms, demonstrated partial effectiveness.³³
  • Symptomatic treatment: one example is a trial evaluating amantadine for its effects on dopaminergic pathways to improve fatigue. Results are encouraging, although larger clinical trials are required.³⁴

Holistic management

Management is guided by the patient’s predominant symptoms:³⁵

  • Fatigue
  • Respiratory symptoms
  • Neurological symptoms
  • Chest pain
  • Pain syndromes
  • Dysautonomic symptoms*
  • Gastrointestinal symptoms
  • Ear, nose and throat disorders
  • Ocular disorders
  • Skin lesions

No symptomatic treatment is contraindicated in long Covid, including non-steroidal anti-inflammatory drugs (NSAIDs) and aspirin.³

For every patient experiencing persistent symptoms, clinicians should consider both the symptoms themselves (particularly cognitive symptoms) and their behavioural and psychosocial consequences.³⁵

In cases where fatigue is associated with post-exertional symptom exacerbation, rehabilitation should be particularly cautious and gradual, with activities carefully paced and broken into manageable periods to avoid triggering symptom flare-ups.³⁶

As with any chronic condition, whether affecting adults, children or adolescents, care should be comprehensive, coordinated and personalised, involving different healthcare professionals according to individual needs.³⁵˒³⁷

In 2024, la Haute Autorité de santé (HAS) published a care pathway guide for adults and adolescents aged 15 years and over with prolonged symptoms following Covid-19. Designed for healthcare professionals, the guide clarifies the roles of different stakeholders and the organisation of care according to the nature of symptoms and the complexity of each patient’s situation.

Its objectives are to provide care tailored to individual needs, reduce diagnostic uncertainty, and facilitate harmonised management across the country.

Management of children and adolescents

As with adults, helping children and adolescents manage their daily activities involves adapting and pacing activities, alternating them with periods of rest to promote satisfactory recovery.³⁷

Adjustments to school attendance may be necessary. An Individualised Healthcare Plan (PAI) can be implemented at school. At the request of the family, it is developed jointly by the head of the educational institution, the physician responsible for the child or adolescent’s care, and the school doctor (or the physician attached to the care facility). This formal agreement defines the support and accommodations required within the educational setting according to the pupil’s specific needs.³⁷

 

*These highly variable symptoms may include dizziness, daytime or night-time sweating, episodes of tachycardia, exercise intolerance, nausea, vomiting, swallowing difficulties, diarrhoea or constipation, urinary incontinence and chills …³⁵

Antiviral treatments

Nirmatrelvir/ritonavir (Paxlovid) is indicated for adult patients who do not require oxygen therapy and who are at high risk of progressing to severe Covid-19.³⁸˒³⁹

The question has been raised as to whether this treatment could improve certain persistent symptoms following SARS-CoV-2 infection.⁴⁰ A study conducted in the United States found no superiority of Paxlovid over placebo in improving fatigue, brain fog*, body aches, cardiovascular symptoms, breathlessness or gastrointestinal symptoms.⁴⁰

 

* Brain fog encompasses impairments in attention, concentration and memory.

Research: ANRS Emerging Infectious Diseases activities

Long Covid Coordinated Action

As early as 2022, ANRS Emerging infectious diseases established a multidisciplinary group bringing together researchers, epidemiologists, sociologists, physicians, patient associations and historians within a long Covid Coordinated Action. The purpose of this steering group is to foster research into the consequences of SARS-CoV-2 infection across epidemiological, pathophysiological, therapeutic and social dimensions.

Long Covid Call for Proposals

In collaboration with the French Ministry of Higher Education, Research and Innovation, the Ministry of Solidarity and Health, and in partnership with the Fondation pour la Recherche Médicale (FRM), ANRS MIE launched a dedicated Long Covid Call for Proposals, implemented through two successive funding rounds. The call focused on priority areas identified by the Coordinated Action:

  • Epidemiology and medico-economic impact
  • Pathophysiology of persistent symptoms
  • Social dimensions of long Covid
  • Therapeutic management

Long Covid Scientific Conference

In October 2024, ANRS MIE, Santé publique France and the French National Authority for Health (HAS) organised a scientific conference on long Covid with the aim of mobilising researchers, patient organisations and public institutions and strengthening collaboration between them.

The conference provided an opportunity to review recent scientific advances, address outstanding questions and identify future research priorities.

Following this event, ANRS MIE identified three major priority areas for future research:

  • Continuing pathophysiological studies
  • Expanding clinical trial development
  • Strengthening research in children

Examples of research projects supported by ANRS MIE

ANRS MIE has supported a range of research initiatives aimed at improving understanding of Long Covid and ultimately enhancing care for people living with the condition.

Examples include:

  • A study conducted in 2020–2021 within the Constances population-based cohort, which identified the persistent symptoms most frequently reported by individuals infected with SARS-CoV-2 compared with the general population.
  • A study published in 2023, which identified several immune markers, some of which could potentially serve as diagnostic tools for Long Covid. The study also suggested viral persistence within the body, particularly in the intestinal mucosa.

ANRS MIE also supports several projects funded through the 2022 Long Covid Call for Proposals.

Visit the Covid-19 Outbreak Response Unit

Access to the website

Publications

Inserm’s open-access journal médecine/sciences is publishing a themed series on long Covid research in 2026. Literature data and personal experience accounts can be found in these issues, which give a voice to researchers, healthcare professionals and patients.

References

  1. Santé publique France. https://www.santepubliquefrance.fr/dossiers/coronavirus-covid-19 (accessed on July 4, 2025)
  2. COVID-19 dashboard by the Center for Systems Science and Engineering (CSSE) at Johns Hopkins University. COVID-19 Map – Johns Hopkins Coronavirus Resource Center. (accessed on July 4, 2025)
  3. HAS. Réponses rapides dans le cadre de la Covid-19 : Symptômes prolongés à la suite d’une Covid-19 de l’adulte – Diagnostic et prise en charge, 2023. Réponses rapides dans le cadre de la Covid-19 : Symptômes prolongés à la suite d’une Covid-19 de l’adulte – Diagnostic et prise en charge (accessed on July 4, 2025)
  4. Ely EW, et al. Long Covid defined. N Engl J Med 2024;391(18):1746-1753
  5. WHO Director-General’s opening remarks at the media briefing on COVID-19 – 21 August 2020. https://www.who.int/fr/director-general/speeches/detail/who-director-general-s-opening-remarks-at-the-media-briefing-on-covid-19—21-august-2020 (consulté le 04/07/2025)
  6. Santé publique France. COVID long : 2 millions de personnes présentaient une affection post- COVID-19 fin 2022. COVID long : 2 millions de personnes présentaient une affection post- COVID-19 fin 2022 (accessed on July 4, 2025)
  7. Coste J, et al. Prevalence of long COVID in the general adult population according to different definitions and sociodemographic and infection characteristics. A nationwide random sampling survey in France in autumn 2022. Clin Microbiol Infect 2024;30(7):924-929
  8. Coronavirus disease (COVID-19): Post COVID-19 condition. Coronavirus disease (COVID-19): Post COVID-19 condition (accessed on July 4, 2025)
  9. Shah DP, et al. Sex differences in long COVID. JAMA Network Open 2025;8(1):e2455430
  10. Greenhalgh T, et al. Long COVID: a clinical update. Lancet 2024;404:707–24
  11. Prevalence of ongoing symptoms following coronavirus (COVID-19) infection in the UK – Office for National Statistics. https://www.ons.gov.uk/peoplepopulationandcommunity/healthandsocialcare/conditionsanddiseases/bulletins/prevalenceofongoingsymptomsfollowingcoronaviruscovid19infectionintheuk/2february2023 (accessed on July 4, 2025)
  12. HAS. Symptômes prolongés à la suite de la Covid-19 : état des lieux des données épidémiologiques, 2023. Symptômes prolongés à la suite de la Covid-19 : état des lieux des données épidémiologiques (accessed on July 4, 2025)
  13. Coste J, et al. A multidimensional network of factors associated with long COVID in the French population. Commun Med (Lond) 2025;5(1):114
  14. Rushyizekera M, et al. Occupational and non-occupational factors of post-COVID-19 condition: a cross-sectional survey in the French general working population. BMJ Public Health 2025;3(1):e001613
  15. Makovski TT, et al. Relationship between multimorbidity, SARS‑COV‑2 infection and long COVID: a cross‑sectional population‑based French survey. BMC Med 2025;23:222
  16. Pastorello A, et al. Temporal changes in the risk of six-month post COVID symptoms: a national population-based cohort study. Am J Epidemiol 2025;194(1):162-171
  17. Camporesi A, et al. Characteristics and predictors of Long Covid in children: a 3-year prospective cohort study. eClin Med 2024;76:102815
  18. Schwartz S, Hummert V. Pediatric Long COVID. Science Insights 2024;45(3):1507–1514
  19. Miller CM, et al. Post-acute sequelae of COVID-19 in pediatric patients within the United States: A scoping review. AJM Open 2024;12:100078
  20. Rao S, et al. Postacute sequelae of SARS-CoV-2 in children. Pediatrics 2024;153(3): e2023062570
  21. Réponses rapides dans le cadre du COVID-19 Symptômes prolongés à la suite d’une Covid-19 de l’enfant et de l’adolescent, 2022. Réponses rapides dans le cadre du COVID-19 Symptômes prolongés à la suite d’une Covid-19 de l’enfant et de l’adolescent. (accessed on July 4, 2025)
  22. Samji H, et al. Review: Mental health impacts of the COVID-19 pandemic on children and youth – a systematic review. Child Adolesc Ment Health 2022;27(2):173-189
  23. Meherali S, et al. Mental health of children and adolescents amidst COVID-19 and past pandemics: A rapid systematic review. Int J Environ Res Public Health 2021;18(7):3432
  24. Chew-Graham CA, et al. Long COVID in children and young people: uncertainty and contradictions. Br J Gen Pract 2022;72(719):253-254
  25. Davis HE, et al. Long COVID: major findings, mechanisms and recommendations. Nat Rev Microbiol 2023;21(3):133-146
  26. Zuo W, et al. The persistence of SARS-CoV-2 in tissues and its association with long COVID symptoms: a cross-sectional cohort study in China. Lancet Infect Dis 2024;24:845–55
  27. Ghafari M, et al. Prevalence of persistent SARS-CoV-2 in a large community surveillance study. Nature 2024;626(8001):1094-1101
  28. Rojas M, et al. Molecular mimicry and autoimmunity. J Autoimmun 2018;95:100-123
  29. Ribi C. Syndrome post-Covid-19 et maladies auto immunes : un parallèle ? https://www.revmed.ch/view/840052/6687069/RMS_776_631.pdf (accessed on July 4, 2025)
  30. Guedj E, et al. L’hypométabolisme cérébral en TEP au 18F-FDG dans le COVID long. Bull Acad Natl Med 2023 ; 207 : 933-946
  31. Zeraatkar D, et al. Interventions for the management of long covid (post-covid condition): living systematic review. BMJ 2024;387: e081318
  32. Kuut TA, et al. Efficacy of cognitive-behavioral therapy targeting severe fatigue following coronavirus disease 2019: Results of a randomized controlled trial. Clin Infect Dis 2023;77: 687–95
  33. Lau RI, et al. A synbiotic preparation (SIM01) for post-acute COVID-19 syndrome in Hong Kong (RECOVERY): a randomised, double-blind, placebo-controlled trial. Lancet Infect Dis 2024;24(3):256-265
  34. Harandi AA, et al. A randomized open-label clinical trial on the effect of Amantadine on post Covid 19 fatigue. Sci Rep 2024;14:1343
  35. HAS. Symptômes dysautonomiques au cours des symptômes prolongés de la Covid-19, 2023. https://www.has-sante.fr/upload/docs/application/pdf/2021-11/fiche_symptomes_dysautonomiques.pdf (accessed on July 4, 2025)
  36. Santé.fr. La fatigue et l’épuisement aggravé par l’effort, symptôme fréquent du Covid long. https://www.sante.fr/covid-long/la-fatigue-et-lepuisement-aggrave-par-leffort-symptome-frequent-du-covid-long (accessed on July 4, 2025)
  37. Ameli. Covid long chez les enfants et les adolescents. Covid long chez les enfants et les adolescents | ameli.fr | Assuré (accessed on July 4, 2025)
  38. Ministère du travail, de la santé, des solidarités et des familles. Tout savoir sur le Covid-19. Tout savoir sur le Covid-19 – Ministère du Travail, de la Santé, des Solidarités et des Familles. (accessed on July 4, 2025)
  39. Fiche : Réponse rapide dans le cadre de la COVID-19 Traitement de la Covid-19. HAS et ANRS MIE, 21 juin 2023. https://www.has-sante.fr/upload/docs/application/pdf/2023-06/reco468_fiche_rr_traitement_covid_19_mel.pdf. (accessed on July 4, 2025)
  40. Geng LN, et al. Nirmatrelvir-Ritonavir and symptoms in adults with postacute sequelae of SARS-CoV-2 Infection: The STOP-PASC randomized clinical trial. JAMA Intern Med 2024;184: 1024–34