The ongoing coronavirus disease 2019 (COVID-19) pandemic has caused considerable damage to global health and the economy. To date, more than 203 million individuals across the world have been infected by the severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), the causative agent of the COVID-19 disease.
The clinical symptoms of the severe COVID-19 have been well described. In addition, scientists have defined the post-acute COVID-19 as the development of sequelae or persistence of symptoms several weeks after the onset of COVID-19 symptoms. In some cases, the symptoms persist for around 3-4 weeks, and in other cases of chronic COVID-19, symptoms may persist beyond 12 weeks from the onset of symptoms.
Previous studies reported that a significant number of individuals severely infected with SARS-CoV-2 experienced long-term clinical symptoms for several months. These studies revealed two symptoms that were more persistent, i.e., fatigue and headaches, even after 28 days of the onset of disease. Several studies also reported a negative impact on the renal function, metabolic response, and cardiovascular systems in individuals with persistent SARS-CoV-2 infection.
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What factors should be included to characterize post-COVID-19 syndromes?
Researchers have suggested that to characterize post-COVID-19 syndromes better, a large study cohort is required that would represent not only COVID-19 symptoms but also include illness events and clinical events. They also feel it is important to study other impacts associated with the pandemic, such as mental health, livelihoods, food security, and mobility. This would prepare clinicians to diagnose patients with post-COVID-19 syndrome and understand which group is most vulnerable to COVID-19. It will also help develop a proper treatment for the patients who suffer from the post-acute-COVID-19 syndrome.
A new study
Researchers have designed a longitudinal study using data from the Innovative Support for Patients with SARS-COV-2 Infections Registry (INSPIRE). This is a secure online platform that contains health information from various sources associated with patients from eight regions across the USA.
In this research, which is available on the medRxiv* preprint server, scientists obtained samples from individuals who were being treated for SARS-CoV-2 infection. These samples included detailed medical interactions, such as clinic visits, hospitalizations, laboratory test reports, medications prescribed, and treatment outcomes as documented in the electronic medical record (EMR).
The main objective of this research is to understand the medium- and long-term sequelae of symptomatic SARS-CoV-2 infection. The researchers also aimed to evaluate the connection between long-term sequelae of COVID-19 and existing syndromes with overlapping features, e.g., myalgic encephalomyelitis/chronic fatigue syndrome (ME/CFS).
The study cohort included 4,800 participants, among which 3,600 were SARS-CoV-2 positive, and 1,200 were SARS-CoV-2 negative (control group). All participants of this study were adults and spoke fluent English or Spanish and self-reported symptoms that indicated acute SARS-CoV-2 infection. They were recruited within forty-two days of having nucleic acid amplification test or antigen test for the detection of SARS-CoV-2. The participants would be analyzed at three months intervals for eighteen months. These data can help researchers determine longitudinal outcomes from SARS-CoV-2 infection and compare the probable risk of outcomes in individuals with and without infection. At present, enrollment of the candidates and follow-up processes are undergoing.
Importance of this study
Epidemiological studies that focus on providing strong evidence on the risk factors, incidence, and history of sequelae of SARS-CoV-2 infection are not widely available.
Previous studies on SARS-CoV-2 infection had many shortcomings in their methodology that led to biased results. Some researchers had only considered patients who were severely infected with SARS-CoV-2 and required hospitalization/intensive care.
These patients were typically at a greater risk of having long-term sequelae than those who received treatment in an ambulatory setting. The current study recruited participants from various settings such as clinics, emergency, and in-patient settings that helped reduce the likelihood of selection bias.
This study reported the impact of extended social isolation on individuals' social, emotional, and functional well-being irrespective of them being infected with COVID-19 or not. Researchers have also highlighted the importance of considering individuals who are not infected with SARS-CoV-2 to understand the incidence of sequelae of COVID-19 illness.
Limitations of this study
One of the limitations of this study is the inclusion of INSPIRE, which requires participants to have some technological literacy. Further, they are needed to have periodic access to the internet, which introduces a data bias regarding who is able to participate.
The longitudinal study design has a risk of attrition as well, because of which every research site tries to monitors research participants' progress and follow up in case a participant fails to provide their quarterly survey reports. Another limitation of this study is poor data quality and misclassification, as it is dependent on the accuracy of electronic medical records.
medRxiv publishes preliminary scientific reports that are not peer-reviewed and, therefore, should not be regarded as conclusive, guide clinical practice/health-related behavior, or treated as established information.