Review of the long-term effects of COVID-19

Coronavirus disease 2019 (COVID-19) has caused over 3.75 million deaths worldwide from infection with the severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In Canada, COVID-19 is responsible for over 1.4 million infections and over 25,000 deaths.

An acute COVID-19 illness usually lasts two to six weeks; however, some patients have reported that debilitating symptoms persist or recur for weeks or months after the acute illness has ended. Affected patients are commonly referred to as “COVID-19 long-distance drivers” or “Long COVID” sufferers.

In a recent study, Canadian researchers documented the prevalence of post-COVID-19 illness at 4-12 weeks (short term) and> 12 weeks (long term) by performing a systematic review of peer-reviewed literature. This work will be published on the medRxiv * preprint server.

The researchers adapted and updated an earlier search strategy from the UK’s National Institute for Health and Care Excellence (NICE). They searched for research published between October 22, 2020 and January 15, 2021 in the following databases: Embase, Medline, PsychInfo, and Cochrane Central.

Interestingly, the work is described as a living systematic review, and researchers assured that they would like to update their results regularly as new evidence emerges, including an update in the fall of 2021.

“This is the first publication of this live review, which is regularly updated as critical additions to the literature are published.”

From this review, the researchers found that while 83% of people reported persistence or presence of one or more symptoms in the short term, 56% reported long-term symptoms. The most common symptoms in both periods included fatigue, general pain or discomfort, difficulty sleeping, shortness of breath, and anxiety or depression.

In addition, the researchers also observed many other mild to severe and debilitating symptoms that occur in a large proportion of convalescent COVID-19 cases.

“Our data show that a significant proportion of people ≥4 weeks after being diagnosed with COVID-19 reported a variety of symptoms,” the researchers interpreted. However, due to the poor certainty of the evidence, they are calling for further research to determine the actual burden of post-COVID-19 conditions.

The researchers presented the PRISMA flowchart of articles through the systematic review process; From the 2807 unambiguous citations, they selected 36 observational studies that met their selection criteria.

Here they looked for the primary endpoints, any symptoms, sequelae, or outcomes related to difficulty performing usual activities (i.e., functional outcomes) reported by people 4 or more weeks after being diagnosed with COVID-19, with the key symptoms being the most significant or sequelae of interest were identified as follows: fatigue, shortness of breath, neurocognitive impairment, pain (in joints, chest, or muscles), organ damage, dizziness, racing heart, tightness or heaviness in the chest, odor and taste disorders, and sleep disorders.

In this review, the researchers used the term “post-COVID-19 illnesses” to describe persistent symptoms that are synonymous with long-term COVID, post-COVID illnesses, chronic COVID syndrome and post-acute consequences of SARS-CoV. 2 are Also the “long-term” is defined as a period of ≥4 to ≥12 weeks after the COVID-19 diagnosis, and the long-term affected patients are referred to as COVID-19 long-distance drivers.

This review found that due to people’s symptoms, about 30% and 10% of them, respectively, were unable to return to work in the short and long term after being diagnosed with COVID-19.

“However, due to the poor certainty of the evidence, real clarity on the burden of post-COVID-19 conditions requires further work to untangle the consequences directly caused by COVID-19 infection from those arising from related factors such as one extensive hospital care results in serious illness. “

They discussed the many limitations in this study; For example, the prevalence of long-term effects in children, in asymptomatic individuals, small sample sizes in many studies or risk biases, presence of other contributing factors, effects of treatment received or effects of hospitalization or ICU admission, and effects due to the pandemic itself (e.g. B. Barriers to receiving treatment, psychosocial effects).

“This evidence is intended to support national and international public health organizations that are in the process of planning and developing supportive measures for patients with post-COVID-19 disease.”

It is estimated that millions of people suffer from post-COVID-19 illness. The impact on health care consumption will be profound and will continue for some time. Therefore, in this study, the researchers emphasized understanding the prevalence of these disorders, the impact on COVID-19 survivors, and the resolution over time – to support and address this problem.

This review highlights the complications and therefore the need for a multidisciplinary approach in developing appropriate diagnostic models and tools, patient care pathways, and support structures to meet the needs of those suffering from post-COVID-19 illness.

*Important NOTE

medRxiv publishes preliminary scientific reports that are not peer-reviewed and therefore are not considered conclusive, guide clinical practice / health-related behavior, or should be treated as established information.

Journal reference:

  • Long-term sequelae prevalence in people diagnosed with COVID-19: a live systematic review, Francesca Reyes Domingo, Lisa A. Waddell, Angela M. Cheung, Curtis L. Cooper, Veronica J. Belcourt, Alexandra ME Zuckermann, Tricia Corrin, Rukshanda Ahmad, Laura Boland, Claudie Laprise, Leanne Idzerda, Anam Khan, Alejandra Jaramillo Garcia, medRxiv 06.03.2021.21258317; doi:,

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