Long COVID

Long COVID, long tail covid, Post-Acute Sequelae of COVID-19 (PASC), post-acute COVID-19 and ongoing COVID are terms used to describe a group of long term health problems that are found in a significant minority of people who developed COVID-19 and remain ill a number of weeks or months later.

The name Long COVID was coined by patient Elisa Perego in May 2020, and in February 2021 the CDC introduced the alternative name Post-Acute Sequelae of COVID-19 (PASC).

In February 2020, the World Health Organization stated that the expected recovery time from COVID-19 was 2 weeks for mild cases, and between three and six weeks for severe cases; follow-up studies then identified a significant number of COVID-19 patients had remained ill much longer than this: those with long COVID.

A similar phenomenon to long COVID occurred after the 2003 outbreak of the similar SARS coronavirus, which lead to a post-SARS syndrome being proposed that included chronic widespread musculoskeletal pain, fatigue, depression and disordered sleep. Another study found a subgroup SARS survivors developed chronic fatigue syndrome immediately after SARS.

Long-haulers
A "long-hauler" is someone with long COVID, meaning someone who became ill with confirmed or suspected COVID-19, who has remained ill with long-term symptoms many weeks or months later after first becoming ill.

What is long COVID
Long COVID appears to be a multisystem disease, and may occur after any severity of COVID-19, including after relatively mild cases.

Signs and symptoms
Patient surveys have reported that the following symptoms commonly occur in long COVID. Other reported symptoms include:
 * Fatigue, which may be extreme (profound)
 * Muscle pain or body aches
 * Breathlessness
 * Concentration problems
 * Inability to exercise/exercise intolerance
 * Headache
 * Insomnia or problems sleeping
 * Heavy chest, a feeling of pressure on the chest, or chest pain
 * Anxiety
 * Muscle weakness
 * Memory problems
 * es
 * Sore throat and difficulty swallowing
 * Heart palpitations
 * Fever
 * Diarrhea
 * Dizziness
 * The sensation of pins and needles
 * Cough
 * Low-grade fever
 * Loss of sense of taste and loss of sense of smell
 * Joint pain
 * New onset allergies, which may lead to anaphylactic shock in some cases
 * New onset diabetes
 * New onset high blood pressure

World Health Organization Long COVID diagnostic criteria
Post COVID-19 condition ("Long COVID") definition
 * history of probable or confirmed SARS-CoV-2 infection
 * symptom(s) last 2 months from the start of COVID-19 (or 3 months for asymptomatic COVID-19)
 * symptom(s) can't be explained by an alternative diagnosis
 * no minimum number of symptoms
 * symptom(s) generally affect day to day functioning
 * new onset of symptoms - symptoms begin after recovery from COVID-19 or begin at the start of COVID-19 and persist
 * symptoms can fluctuate or improve then relapse over time

Common symptoms: Other symptoms: Notes:
 * fatigue
 * shortness of breath
 * cognitive dysfunction but there are others
 * abdominal pain, menstrual and period problems, altered smell/taste, anxiety, blurred vision, chest pain, cognitive dysfunction (e.g. brain fog), cough, depression, dizziness, fatigue, intermittent fever, gastrointestinal issues (diarrhoea, constipation, acid reflux), headache, memory issues, joint pain, muscle pain, muscle spasms, neuralgias (nerve pain), new onset allergies, pins and needles sensations, post-exertional malaise, shortness of breath, sleep disorders, tachycardia/palpitations, tinnitus and other hearing issues
 * Children - separate criteria may be needed
 * Clusters - clusters of 2 or more related symptoms may occur together

Four different syndromes
A recent review suggested that long COVID may actually be four different syndromes: Patients with long COVID may have several syndromes at once.
 * Post-Intensive Care Syndrome
 * Postviral Fatigue Syndrome (ME/CFS)
 * Long Term COVID Syndrome
 * Permanent organ damage

COVID-19 testing
While some people with long COVID did have a positive test result for COVID-19, others were denied tests due to the limited availability of tests at the time, or they tested negative but were found to have clear evidence of COVID-19 from blood count tests or chest X-rays. Some people with Long COVID have described never having a cough or fever at the start of their illness, but developed these symptoms later. Long COVID diagnosis does not depend on a previous positive test.

Clinical findings
There is no blood test or diagnostic biomarker to identify patients with long COVID. A study of UK patients by Dennis et al (2020) found that just over 10% of long COVID patients had abnormal findings on the standard tests and did not find an association between standard test results and degree of organ damage or long COVID severity. The same study used MRI scans combined with patient questionnaires to assess organ damage, finding that multi-organ impairment was common in people with long COVID, despite the fact that 80% had not been hospitalized for COVID-19, the average patient age was forty-four years old, and rates of pre-existing conditions were also low.

Research findings
Surveys of data collected and published by long haulers using social media were the first evidence of what symptoms and health problems were caused by long COVID. Later academic studies confirmed many of the initial long hauler survey findings, although many only involved patients discharged from hospital, patients who had been able to access early testing and tested positive, or patients who had sought medical care in a particular location. People with mild COVID-19 symptoms, leaving people denied testing and those who may have had false negative test results and people who tested positive but were asymptomatic underrepresented in long COVID research.

Pacing
Pacing is a method of activity management which aims to adapt everday activities in order to avoid relapses or increased symptoms.

Exercise therapy
ME/CFS patient groups have raised concerns about the use of graded exercise therapy (GET) in long COVID patients and a similar warning has been issued by NICE in the UK. Graded exercise therapy, which is sometimes incorrectly referred to as "activity management" involves patients initially reducing their activity levels to a level that prevents regular crashes, and then typically increasing activity by 10% each week regardless of any increased symptoms or worsening illness. In graded exercise patients are told to ignore deterioration or increased symptoms and "push through" them.

Theory and evidence
In graded exercise therapy patients are told that their symptoms are caused only by inactivity and other "bad habits" rather than an underlying illness. These assumptions have very weak evidence, and significant evidence exists of underlying illness in ME/CFS; there is a lack of research about exercise therapy for long COVID illness but some symptoms are inconsistent with this "deconditioning" assumption and some research has found physical abnormalities in some patients weeks or month after infection. Surveys of ME/CFS patients have consistently shown that large numbers of patients deteriorate as a result of graded exercise therapy, and a significant number become severely ill and never return to the level of functioning they had before the treatment.

ME/CFS
Postviral fatigue syndrome is one of the previous names used for Myalgic Encephalomyelitis (ME), sometimes known as Chronic Fatigue Syndrome (CFS), and it commonly begins immediately after events such as a virus, bacterial or other infection. ME has been a sequela of over one hundred outbreaks, in addition to sporadic infections. ME/CFS is not normally diagnosed until symptoms have persisted for six months or more, and tests must be run to exclude other possible causes of the symptoms. Some contagious diseases including Epstein-Barr virus, certain enteroviruses, and the SARS coronavirus, have caused outbreaks of ME/CFS. It is not yet known how likely it is for ME/CFS to begin immediately after COVID-19 illness, although around 10% people with certain viruses are known to develop ME/CFS, and according to the BMJ around 10% of people with COVID-19 have developed long COVID. A significant number of those with long COVID have been found to develop ME/CFS, but it is not known how common this is.

Patient surveys
Not peer reviewed
 * May 2020, What Does COVID-19 Recovery Actually Look Like? An Analysis of the Prolonged COVID-19 Symptoms Survey by Patient-Led Research Team - by Body Politic and Patient Led Research Collaborative
 * Data collected: Apr 21 - May 2 2020. Respondents: 640


 * Jul 2020, COVID-19 “Long Hauler” Symptoms Survey Report - with Survivor Corps
 * Data collected: Jul 25, 2020. Respondents: 1,567+
 * Dec 2020, Charactering Long COVID in an International Cohort: 7 Months of Symptoms and Their Impact - by Body Politic and Patient Led Research Collaborative
 * Respondents: 3,762+
 * Respondents: 3,762+

Notable studies

 * Jul 24, 2020, Outcomes of Cardiovascular Magnetic Resonance Imaging in Patients Recently Recovered From Coronavirus Disease 2019 (COVID-19) - (Full text)
 * Aug 11, 2020, Management of post-acute covid-19 in primary care - (Full text)
 * Aug 20, 2020, New-Onset Diabetes in Covid-19 - (Full text)
 * Oct 1, 2020, Long-term consequences of COVID-19: research needs - (Full text)
 * Oct 14, 2020, Finding the 'right' GP: a qualitative study of the experiences of people with long-COVID - (Full text)
 * Oct 16, 2020, Multi-organ impairment in low-risk individuals with long COVID - (Full text)
 * Oct 21, 2020, Attributes and predictors of Long-COVID: analysis of COVID cases and their symptoms collected by the Covid Symptoms Study App - (Full text)
 * Dec 2020 (pre-print) / Jul 15, 2021, Characterizing long COVID in an international cohort: 7 months of symptoms and their impact - (Abstract)
 * Dec 2020, Long COVID-19: Challenges in the diagnosis and proposed diagnostic criteria (Full text)
 * Dec 20, 2020, Patient outcomes after hospitalisation with COVID-19 and implications for follow-up; results from a prospective UK cohort - (Full text) - from the DISCOVER project
 * Jan 18, 2021, Will COVID-19 lead to myalgic encephalomyelitis/chronic fatigue syndrome? - (Full text)
 * Mar 27, 2021, COVID-19 Survivors’ Reports of the Timing, Duration, and Health Impacts of Post-Acute Sequelae of SARS-CoV-2 (PASC) Infection - (Full text)
 * May 11, 2021, Mayo Clinic Proceedings: Post COVID-19 Syndrome (Long Haul Syndrome): Description of a Multidisciplinary Clinic at the Mayo Clinic and Characteristics of the Initial Patient Cohort - (Abstract)
 * Jun 7, 2021, Insights from ME/CFS May Help Unravel the Pathogenesis of Post-Acute COVID-19 Syndrome - (Full text)
 * Jun 23, 2021, Long COVID or Post-acute Sequelae of COVID-19 (PASC): An Overview of Biological Factors That May Contribute to Persistent Symptoms - (Full text)
 * Oct 2021, A clinical case definition of post COVID-19 condition by a Delphi consensus (Full text)
 * Report including the World Health Organization Long COVID diagnostic criteria

Articles and editorials

 * Jun 15, 2021, White Paper: A Detailed Study of Patients with Long-Haul COVID (Full text)
 * Jun 24, 2021, Covid-19: Third of people infected have long term symptoms (Editorial)

Presentations, interviews and videos

 * Aug 2020, Will Covid-19 lead to ME/CFS in some people? - presentation - Dr Anthony Komaroff
 * Jul 2020, Message in a Bottle video - LongCovidSOS
 * Jun 2020, Health of Corona Patients at Home in Alarmingly Poor Health Even After Several Months - Dutch Lung Foundation - Press release (English translation) - Dutch

Letters and blogs

 * May 2020, Very, very mild: Covid-19 symptoms and illness classification - Felicity Callard
 * Jul 2020, Letter re Covid-19 Management and Exercise Caution - Forward-ME
 * Sep 2020, Understanding Long Covid, A Shortcut to Solving ME/CFS? - Simon McGrath
 * Sep 2020, Why the Patient-Made Term 'Long Covid' is needed - Open Letter
 * Oct 2020, Why we need to keep using the patient made term “Long Covid” - The BMJ
 * Jan 2021, Trying to Make Sense of Long COVID Syndrome - Dr. Francis Collins, CDC director

National and international health bodies

 * NICE cautions against using graded exercise therapy for patients recovering from COVID-19

News articles

 * Oct 2020, Women aged 50-60 at greatest risk of ‘long Covid’, experts suggest - The Guardian


 * Oct 2020, These Doctors Have Long-Term Covid. Now They’re Pushing for Better Care. - Wall Street Journal
 * Oct 2020, Have We Been Thinking About Long-Haul Coronavirus All Wrong? - Time
 * Oct 2020, Living with COVID: NIHR publishes dynamic-themed review into 'ongoing COVID' - National Institute of Health Research
 * Oct 2020, Long Covid: the evidence of lingering heart damage - The Observer
 * Sep 2020, Coronavirus patient unable to work six months on - BBC News
 * Aug 2020, The Most Common Long-Term Symptoms Of Covid-19 - HuffPost UK
 * Jul 2020, From ‘brain fog’ to heart damage, COVID-19’s lingering problems alarm scientists - Science Mag

Learn more

 * COVID-19 Long Term Health Effects
 * Infographic: "Long covid" in primary care - BMJ journal
 * List of long COVID studies (draft) - #MEAction