Evidence map›Paper›PMID 34024217›Full record

ReviewInfectious diseases (London, England)2021

Long COVID or post-COVID-19 syndrome: putative pathophysiology, risk factors, and treatments.

Shin Jie Yong

Registry-linked trialOpen access · greenAbstract readReview
PubMed Full text at PMC Publisher
In one paragraph

Review in Infectious diseases (London, England), 2021. The graph could read no effect estimate from its abstract, so it casts no vote on the map. It is linked to trial NCT05950230 (A Case-Control Study on the Association Between Periodontal Health and Gingival Crevicular Level of Matrix Metalloproteinase-8 in Post COVID-19 Patients), which is not on this map. Cited by 673 papers, 7 of them syntheses that pooled it.

0numbers the graph read from it
0cells of the map it votes in
673citing papers in PubMed, 7 pooled it
122.1field-weighted citation impact, top 1% of its field
1 · What the graph read from it

What it found

Each row is one number read from the abstract, on the scale the paper reported it, with its interval. Left of the dashed line favours the treatment, right favours the comparator. Under each row is the sentence it came from. New to these charts? A ten-minute tutorial.

The abstract states no effect estimate the extractor could read, or names no intervention and outcome on the map, so this paper lights no cell and moves no belief. It is still indexed, cited and linked below.

2 · The registry

The trial behind it

Trials whose registry record cites this paper, or whose number appears in the abstract. A trial that started after this paper was published is citing it as background, not reporting it.

NCT05950230 unknown statusnot on this mapstarted 2023, after this paper: background citation

A Case-Control Study on the Association Between Periodontal Health and Gingival Crevicular Level of Matrix Metalloproteinase-8 in Post COVID-19 Patients

TypeobservationalSponsorAin Shams UniversityRan2023 to 2023Enrolled90ConditionsPost COVID-19 ConditionArmsAssess Periodontal Health Status, Collecte GCF samples by paperstrip
3 · Its place in the literature

Who cites it

673 citing papers in PubMed, 7 syntheses or guidelines pooled it, 1,316 citations in OpenAlex.

  1. Pooled it
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  8. Trial
  9. Long COVID Optimal Health Programme to Enhance Mental and Physical Health: A Feasibility Randomised Controlled Trial.Health expectations : an international journal of public participation in health care and health policy · 2025
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  20. Understanding the Impact of Long COVID on the Lives of Thai University Students.International journal of environmental research and public health · 2026
    Article

613 more citing papers are in PubMed but not listed here.

4 · The record

Corrections and comments

PubMed lists nothing against this paper. Absence here is not a guarantee, only a check that was made.

5 · Who and what money

Authors and funding

1 author at 1 institution in 1 country.

Shin Jie YongDepartment of Biological Sciences, School of Medical and Life Sciences, Sunway University, Subang Jaya, Malaysia.ORCID 0000-0001-9752-8386
Sunway University · MY

Funding

No grant is acknowledged in the PubMed record.

6 · The paper itself

Abstract

Long COVID or post-COVID-19 syndrome first gained widespread recognition among social support groups and later in scientific and medical communities. This illness is poorly understood as it affects COVID-19 survivors at all levels of disease severity, even younger adults, children, and those not hospitalized. While the precise definition of long COVID may be lacking, the most common symptoms reported in many studies are fatigue and dyspnoea that last for months after acute COVID-19. Other persistent symptoms may include cognitive and mental impairments, chest and joint pains, palpitations, myalgia, smell and taste dysfunctions, cough, headache, and gastrointestinal and cardiac issues. Presently, there is limited literature discussing the possible pathophysiology, risk factors, and treatments in long COVID, which the current review aims to address. In brief, long COVID may be driven by long-term tissue damage (e.g. lung, brain, and heart) and pathological inflammation (e.g. from viral persistence, immune dysregulation, and autoimmunity). The associated risk factors may include female sex, more than five early symptoms, early dyspnoea, prior psychiatric disorders, and specific biomarkers (e.g. D-dimer, CRP, and lymphocyte count), although more research is required to substantiate such risk factors. While preliminary evidence suggests that personalized rehabilitation training may help certain long COVID cases, therapeutic drugs repurposed from other similar conditions, such as myalgic encephalomyelitis or chronic fatigue syndrome, postural orthostatic tachycardia syndrome, and mast cell activation syndrome, also hold potential. In sum, this review hopes to provide the current understanding of what is known about long COVID.

Indexed as

COVID-19Mental DisordersFemaleHumansPost-Acute COVID-19 SyndromeRisk FactorsSARS-CoV-2drug repurposinglong COVIDLong-haul COVID-19pathophysiologypost-COVID-19 syndromerisk factors

Identifiers

PMID34024217
PMCPMC8146298
OpenAlexW3165449608

What OpenQuestion holds

Textmetadata
Read underepoch 390

Registered trials

Read under generation 80e0d062 · epoch 390. Bibliography from PubMed, PubMed Central and OpenAlex; grants from NIH RePORTER; trial links from ClinicalTrials.gov; estimates, votes and beliefs from the OpenQuestion graph.