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Vol. 221. Issue 10.
Pages 614-616 (December 2021)
Vol. 221. Issue 10.
Pages 614-616 (December 2021)
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What are we talking about when we talk about post-COVID-19?
¿De qué hablamos cuando hablamos de pos-COVID-19?
E. Cairolia,b,c
a Unidad Pos-COVID-19, Centro Asistencial del Sindicato Médico del Uruguay (CASMU) y Unidad de Seguimiento Pos-COVID-19, Cooperativa Regional de Asistencia Médica Integral (CRAMI), Montevideo, Uruguay
b Unidad de Enfermedades Autoinmunes, Centro Asistencial del Sindicato Médico del Uruguay (CASMU) y Hospital Evangélico, Montevideo, Uruguay
c Laboratorio de Inmunorregulación e Inflamación, Institut Pasteur de Montevideo, Montevideo, Uruguay
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Tables (1)
Table 1. Definitions used in the scientific literature on clinical manifestations present following the acute phase of COVID-19.
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Dear Director,

SARS-CoV-2 (severe acute respiratory syndrome coronavirus 2), the etiological agent of COVID-19 (coronavirus disease 2019), caused a pandemic of such a magnitude that it led to the collapse of healthcare institutions and economic and social fracturing; the term “post-COVID-19” has become part of daily conversation in various areas of life.

In terms of health, “post-COVID-19” is used to refer to the persistence of signs and symptoms in individuals who have passed the acute phase of the infection. Once the disease has been overcome, it is estimated that from 10% to 20% of individuals will continue to have a series of symptoms such as fatigue, headache, anxiety, “brain fog,” insomnia, cough, dyspnea, chest pain, arthralgia, myalgia, and diarrhea (among others). All these symptoms fluctuate and are heterogeneous in their characteristics and intensity1.

This set of signs and symptoms that persist following COVID-19 has been referred to in a variety of ways over the past year: post-COVID-19 syndrome, post-COVID conditions, long COVID, persistent COVID, post-acute COVID-19, post-acute sequelae of COVID-19, long-haul COVID, and chronic post-COVID syndrome, to cite just the most noteworthy (Table 1).

Table 1.

Definitions used in the scientific literature on clinical manifestations present following the acute phase of COVID-19.

Authors  Definition in Spanish  Definition used in the original publication  Times considered in the definition  Other definitions considered  Reference 
National Institute for Health and Care Excellence (NICE)  Síndrome pos-COVID-19  Post-COVID-19 syndrome  More than 12 weeks  Ongoing symptomatic COVID: 4–12 weeks. Long COVID: 4 weeks and on  COVID-19 rapid guideline: managing the long-term effects of COVID-19. diciembre de 2020 
World Health Organization (WHO)  Condiciones pos-COVID-19  Post-COVID-19 conditions  After 4 weeks  Short-term (4–8 weeks), medium-term (2–6 months), long-term (more than 6 months)  Expanding our understanding of post COVID-19 condition. Report of a WHO webinar. febrero de 2021 
Centers for Diseases Control and Prevention (CDC)  Condiciones pos-COVID  Post-COVID conditions  More than 4 weeks  Post-acute sequelae of COVID, PASC abril de 2021 
Sociedad Española de Médicos Generales y de Familia (SEMG) and LongCovidACTS  Long-COVID/COVID persistente  Long COVID/COVID persistente  More than 4 weeks  Post-COVID-19 syndrome: referring to sequelae of COVID.  Clinical guidelines for the care of long COVID/persistent COVID patients. Version 1.0. mayo de 2021 
Nalbandian A, Sehgal K, Gupta A, Madhavan MV, McGroder C, Stevens JS, et al.  COVID-19 posaguda  Post-acute COVID-19  More than 4 weeks  Subacute — ongoing symptomatic COVID-19 and chronic or post-COVID-19 syndrome)  Nature Medicine. April 2021; 27: 601–615 
Al-Aly Z, Xle Y, Bowe B  Secuelas posagudas de la COVID-19  Post-acute sequelae of COVID-19  More than 30 days  NA  High-dimensional characterization of post-acute sequelae of COVID-19. Nature. 2021 Jun; 594:259-64. 
Datta SD, Talwar A, Lee JT  Secuelas tardías de la infección por SARS-CoV-2  Late sequelae of SARS-CoV-2 infection  More than 4 weeks  SARS-CoV-2 long haulers  A proposed framework and timeline of the spectrum disease due to SARS-CoV-2 infection. Illness beyond acute infection and public health implications. JAMA. 2020;324:2251–2. 
Nath A  Portador de largo plazo COVID  Long-Haul COVID  More than 100 days  Long-tail COVID  Long-haul COVID. Neurology. 2020;95:559–60 
Fernández de Las Peñas C, Palacios Ceña D, Gómez Mayordomo V, Cuadrado ML, Florencio L  Síntomas pos-COVID agudo  Acute post-COVID symptoms  More than 4 weeks  Long post-COVID symptoms; Persistent post-COVID symptoms  Defining post-COVID symptoms (post-acute COVID, long COVID, persistent pos-COVID): an integrative classification. Int J Environ Res Public Health. 2021;18:2621. 
Iqbal FM, Lam K, Sounderajah V, Clarke JM, Ashrafian H, Drazi A  Síndrome pos-COVID crónico  Chronic post-COVID syndrome  More than 12 weeks  Acute post-COVID syndrome, less than 12 weeks  Characteristics and predictors of acute and chronic post-COVID syndrome: a systematic review and meta-analysis. EClin Med. 2021;24;36:100899 

COVID-19: coronavirus disease 2019; SARS-CoV-2: severe acute respiratory syndrome coronavirus 2.

So what are we talking about when we talk about “post-COVID-19” manifestations? The first guidelines published used the designation “post-COVID-19 syndrome” to refer to the signs and symptoms that develop during or after the infection which continue for more than 12 weeks and which cannot be explained by an alternative diagnosis. They also use the term “long COVID” to refer to the clinical symptoms that follow the acute phase (four weeks) and continue beyond 12 weeks (encompassing post-COVID-19 syndrome)1.

Later, the World Health Organization and the Centers for Disease Control and Prevention used the term “conditions” to refer to post-COVID-19 manifestations, with the World Health Organization assigning the ICD-10 code U09.9 for post-COVID conditions. More recently, various scientific and patient organizations have used the terms “long COVID” and “persistent COVID” without the “post-” prefix, given that it refers to a disease which has been overcome, which is in contrast to the pathogenic hypothesis of the existence of reservoirs with viral persistence2.

None of the proposed terms is entirely accurate; all have strengths and weaknesses and an agreement has yet to be reached on how to define this situation. What remains to be determined is:

  • a)

    The name that best identifies it.

  • b)

    The time periods to consider for its start (3, 4, 12, 24 weeks).

  • c)

    The signs and symptoms that should be included, given that in the etiopathogenesis, presence of the following must be clarified: 1) sequelae due to fibrosis and thromboembolism, 2) persistent inflammation, 3) autoimmune reactions, and 4) persistence of intestinal viral reservoirs.

  • d)

    Confirmed, probable, or possible entities should be considered based on the type of study that verifies the presence of SARS-CoV-2 infection (RT-PCR, antigen detection test, antibody detection)3,4.

From a clinical-pathological point of view, it overlaps with the coexistence of manifestations due to a) sequelae induced by SARS-CoV-2 (fibrosis, thrombosis); b) manifestations related to persistent inflammatory activity (systemic inflammation, autoimmune reactions, or SARS-CoV-2 persistence); and c) sequelae of hospitalization, mainly in those who required intensive care unit (ICU) care3,4.

Considering this variability, it is possible to distinguish the following clinical phenotypes:

  • a.

    Predominantly respiratory pattern (those treated in the ICU, pulmonary fibrosis, organizing pneumonia).

  • b.

    Cardiorespiratory pattern with cardiovascular symptoms and a lesser degree of lung damage (non-hospitalized patients, chest pain, tachycardia, postural orthostatic tachycardia syndrome, imaging tests, and lung function without significant damage).

  • c.

    Psychoneurocognitive pattern (altered memory, “brain fog,” insomnia, anxiety, depression, headache).

  • d.

    Pattern with persistent inflammatory activity, which can be concomitant with the above patterns3,4.

It is possible that post-COVID-19 syndrome, long COVID, persistent COVID, and other terms used in the literature represent multiple syndromes that are the result of past or persistent pathological processes, of which is its essential to learn the etiopathogenesis.

At present, it is possible to use an umbrella term that encompasses post-COVID-19 manifestations and understand it, at least for the time being, as a concept or various concepts under construction, with certainties, unknowns, and overlapping, until it can be redefined in light of conclusive scientific evidence.

The answers will come from research, which must draw from clinical practice with the emergence of multidisciplinary post-COVID-19 groups, units, and clinics that allow for determining all clinical profiles in depth and examining the model to identify phenotypes that allow for better establishing prognosis and using treatments tailored to each clinical profile.


This work has not received any type of funding.

Conflicts of interest

The author declares that there are no conflicts of interest.

COVID-19 rapid guideline: managing the long-term effects of COVID-19. National Institute for Health and Care Excellence (NICE). 18 December 2020 [Accessed 18 June 2021]. Available from:
Guía clínica para la atención al paciente long COVID/COVID persistente. SEMG (Sociedad Española de Médicos Generales y de Familia). LongCovidACTS (Autonomous Communities Together Spain). Documento colaborativo entre colectivos de pacientes y sociedades científicas Versión 1.0. (01/05/2021) [Accessed 5 May 2021]. Available from:
S.J. Yong.
Long COVID or post-COVID-19 syndrome: putative pathophysiology, risk factors and treatments [published online ahead of print, 2021 May 22].
C. Fernández de las Peñas, D. Palacios-Ceña, V. Gómez-Mayordomo, M.L. Cuadrado, L.L. Florencio.
Defining post-COVID symptoms (post-acute COVID, long COVID, persistent post-COVID): an integrative classification.
Int J Environ Res Public Health, 18 (2021), pp. 2621

Please cite this article as: Cairoli E. ¿De qué hablamos cuando hablamos de pos-COVID-19? Rev Clin Esp. 2021;221:614–616.

Copyright © 2021. Elsevier España, S.L.U. and Sociedad Española de Medicina Interna (SEMI)
Revista Clínica Española (English Edition)

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