#17,096
One of the great medical mysteries of the 20th century was an epidemic of neurological illness that occurred over the decade that followed the great influenza pandemic of 1918.
The NIH describes the disease as:
Encephalitis lethargica is a disease characterized by high fever, headache, double vision, delayed physical and mental response, and lethargy. In acute cases, patients may enter coma. Patients may also experience abnormal eye movements, upper body weakness, muscular pains, tremors, neck rigidity, and behavioral changes including psychosis. The cause of encephalitis lethargica is unknown.
Between 1917 to 1928, an epidemic of encephalitis lethargica spread throughout the world, but no recurrence of the epidemic has since been reported. Postencephalitic Parkinson's disease may develop after a bout of encephalitis-sometimes as long as a year after the illness.
It has been estimated that between 1 and 5 million people were afflicted with EL between 1917 and 1927 - and while roughly 1/3rd died during the acute phase of the illness - many of the survivors would go on to develop Parkinsonian features and other profound neurological sequelae, often years later.
While a direct link to the 1918 pandemic virus has never been established, many researchers believe this epidemic was caused by a virus (see Evidence for an enterovirus as the cause of encephalitis lethargica).
Throughout history, there have been reports of similar outbreaks, resulting in severe neurological disease, including febris comatosa which sparked a severe epidemic in London between 1673 and 1675, and in 1890 in Italy, in the wake of the 1889–1890 influenza pandemic, a severe wave of somnolent illnesses (nicknamed the "Nona") appeared.
Likewise with SARS-CoV-2 infection we are seeing large number of `recovered' cases who have reported a wide spectrum of chronic, and often debilitating symptoms - often dubbed `Long COVID'.
These symptoms (including fatigue, recurrent fevers, `brain fog', myalgias, etc. ), are highly reminiscent of ME/CFS - which has disabled and traumatized well over a million Americans over the past 3 decades (see NIH About CFS/ME).
A few (of many) blogs on this topic include:
MMWR: Post–COVID-19 Symptoms and Conditions Among Children and Adolescents
More Evidence On The Long-term Impact of SARS-CoV-2 Infection
Nature: Long COVID After Breakthrough SARS-CoV-2 Infection
BMJ: Elevated Risk Of Blood Clots Up To 6 Months After COVID Infection
Diabetologia: Incidence of Newly Diagnosed Diabetes After Covid-19
The evidence continues to mount that COVID infection can produced long-lasting, even permanent, sequelae even in those who were not sick enough during the acute phase of their illness to require hospitalization.
While the definition of `post-COVID' syndromes varies, and some lingering damage may not become fully apparent for years in some individuals (see Coronavirus Disease 2019 (COVID-19) and the Heart—Is Heart Failure the Next Chapter? by Clyde W. Yancy, MD, MSc1,2; Gregg C. Fonarow, MD3,4), researchers are attempting to quantify the size of the problem.
Which brings us to the following systematic review, published today by the ECDC, that finds slightly more than half of COVID patients report at least 1 lingering symptom (primarily fatigue, shortness of breath, depression, headache and dizziness) after recovering from COVID.
The ECDC warns:
There are still many unknowns, in terms of current and future risks to populations for post COVID-19 condition in the context of increased levels of vaccination and hybrid immunity. Looking ahead, additional large-scale population-based studies with appropriate control groups are required to assess which long-term symptoms are specifically attributable to SARS-CoV-2 infection and their association with a wide range of demographic and clinical risk factors.
You'll find the executive summary below. Follow the link to read the report in its entirety.
Prevalence of post COVID-19 condition symptoms: a systematic review and meta-analysis of cohort study data, stratified by recruitment setting
Systematic review
31 Oct 2022
The primary aim of this systematic review and meta-analysis was to estimate the prevalence of symptoms of post COVID-19 condition, stratified by recruitment setting (community, hospital and Intensive Care Unit (ICU)) as a proxy for disease severity.
Executive summary
- Post COVID-19 condition may pose a threat to healthcare systems already stretched after the acute phase of the COVID-19 pandemic, and its management remains a challenge to healthcare providers. This systematic review of the literature aims to identify reported symptoms of post COVID-19 condition within patient cohorts.
- The primary aim of this systematic review and meta-analysis was to estimate the prevalence of symptoms of post COVID-19 condition, stratified by recruitment setting (community, hospital and Intensive Care Unit (ICU)) as a proxy for disease severity. Only prospective and retrospective cohort studies conducted in Europe, European Union (EU)/European Economic Area (EEA) countries, the United Kingdom, USA, Canada, Australia and New Zealand were considered.
- The Grading of Recommendations Assessment, Development and Evaluation (GRADE) methodology was used to evaluate the certainty of evidence for each outcome of interest. Of 7 125 peer-reviewed studies initially identified, 61 cohort studies from 15 countries were included in the analysis. These studies included 74 213 post COVID-19 condition cases that had been assessed at least 12 weeks after SARS-CoV-2 infection.
- An extremely wide range of physical and psychological symptoms are reported by individuals at least 12 weeks after a SARS-CoV-2 infection.
- Prevalence estimates for five symptoms (fatigue, shortness of breath, depression, headache and dizziness) associated with post COVID-19 condition were supported by evidence scored as high or moderate certainty across both the community and hospital recruitment settings. Each of these five symptoms were noted to be more prevalent among patients recruited in the hospital setting when compared to the community setting, indicating that risk of post COVID-19 condition may be higher among individuals who experience more severe COVID-19 disease.
- Overall, the prevalence of any post COVID-19 condition symptom was estimated at 51% among cohorts recruited in the community setting. However, there was high variability in symptom prevalence estimates between individual studies. This is the result of considerable heterogeneity in cohort study designs developed to investigate post COVID-19 condition, which often lack the control groups necessary to compare symptoms reported among SARS-CoV-2 infected individuals and non-infected individuals.
- Consequently, symptom prevalence estimates must be interpreted with caution as studies lacking non-infected comparator groups may overestimate symptoms specifically attributable to prior SARS-CoV-2 infection. For example, a recently published prospective, population-based, observational cohort study of 76 422 participants in the Netherlands, which corrected for pre-existing symptoms before the onset of COVID-19, as well as symptomatic conditions in a control group, estimates that approximately one in eight people (12.7%) with COVID-19 in the general population will develop post COVID-19 condition, which is far lower than the prevalence estimated in this review.
- While this review may assist policymakers and public health authorities in estimating the burden of post COVID-19 condition and support the planning of rehabilitation services during the post-acute phase of the COVID-19 pandemic, there are important limitations to this work. Due to the time-lag between study design, implementation and publication, results in this systematic review reflect the status quo following the first waves of the pandemic (i.e. pre-Omicron period), where historical variants were in circulation and population-level immunity was markedly different.
- There are still many unknowns in terms of current and future population risk for post COVID-19 condition in the context of increased levels of vaccination and hybrid immunity. Looking ahead, additional large-scale population-based studies with appropriate control groups are required to assess the long-term symptoms specifically attributable to SARS-CoV-2 infection, and their association with a wide range of demographic and clinical risk factors.
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