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So-called COVID-19 'Long Haulers' Experience Symptoms after Recovery from Acute Illness
March  2021

There is accumulating evidence from observational data that suggests a significant proportion of patients may experience a wide range of symptoms after recovery from acute illness. Some aspects may be unique to COVID-19, but many appear similar to recovery from other viral illnesses. 

The condition goes by a variety of names: Long COVID, “long haulers”, Post-Acute COVID-19, Post-Acute Sequelae of SARS-CoV-2 infection (PASC). PASC unfortunately, does not have a definition for length of time nor symptomatology. 

While there is frequent public media attention, there is scant peer reviewed literature on this subject. Much of the literature is survey based, which poses some generalizability issues.  Ideally, all patients from various locations diagnosed with COVID-19 would be followed long term for accurate data.

PASC may overlap with other complications of acute COVID-19, making it hard to define. Hospital acquired infections, deconditioning and complications from COVID-19 itself as well as post intensive care syndrome can lead to long term consequences.

Although PASC appears to be more prevalent in those who were more acutely ill, it is noted in patients who were never hospitalized as well.  Some of the most commonly listed symptoms include:

​Persistent fatigue
​Brain fog (mild subjective cognitive impairment)
Sleeping difficulties
​Smell disorders
​Chest pain

Possible mechanisms of PASC symptoms include:
  • Residual inflammation from a dysregulated immune response
  • Organ dysfunction that persists after acute infection
  • Lingering virus may be “hidden” in a privileged site, as, replication-competent virus is rarely recovered beyond 20 days of symptom onset.
  • Possible neuro-invasion leading to neuropsychiatric symptoms
  • Endothelial injury along with diffuse thrombosis with microangiopathy
Currently, there is limited information on the incidence, prevalence, duration, underlying causes and effective treatments for these lingering signs and symptoms. The full spectrum of PASC is currently unknown. Consensus towards definitions as well as more research and rigorous observational cohort studies are needed.  

Post-COVID-19 centers are opening at academic centers in the US. The National Institute of Health has published guidelines for the management of COVID-19 which are continually updated as more information is discovered. It includes a section on persistent symptoms. 

Additional Research