Long COVID Syndrome: A Systematic Review of Persistent Symptoms Post-Pandemic

Abstract

The manifestation of persistent symptoms following COVID-19 infection, also known as Long COVID, is recognized by the World Health Organization. However, uncertainties remain regarding the symptoms, definitions of this condition, and its manifestation in the population. Therefore, this systematic review aims to provide an overview of the centrally published reviews describing persistent symptoms and critically analyze existing studies to identify gaps and propose new research perspectives. Initially, relevant studies were researched, followed by selection based on the titles and abstracts of articles obtained from the PubMed electronic database up to May 2023. Subsequently, the selected studies underwent a thorough analysis and interpretation of results, and pre-defined inclusion and exclusion criteria were considered. The inclusion criteria considered only English articles that conducted systematic reviews and meta-analyses of primary studies on persistent symptoms following SARS-CoV-2 infection. To maintain the generalizability of the results, studies that restricted the age of participants or considered samples with specific clinical conditions (comorbidities) were excluded. A total of 10 articles published between 2021 and 2022 were identified, encompassing a sample ranging from 4,664 to 257,348 adult patients, predominantly from the northern hemisphere. The studies focus on identifying the prevalence of symptoms following acute infection in individuals who tested positive for COVID-19, regardless of hospitalization status. Only one article offered a comparative perspective between positive and negative groups. The post-acute phase range varied from short periods (14 days) to long-term (over one year). The prevalence of symptoms varied over time. The most prevalent symptoms of Long COVID, regardless of the post-acute phase time range, were fatigue and dyspnea. A knowledge gap was identified in this research field, necessitating further investigation and the search for solid evidence to understand the persistent symptoms associated with COVID-19.