Long COVID or Post-Acute Sequelae of SARS-CoV-2 Infection (PASC) and the Urgent Need to Identify Diagnostic Biomarkers and Risk Factors.

Long COVID, or post-acute sequelae of SARS-CoV-2 infection (PASC), also known as post-COVID-19 condition or post-COVID syndrome, can affect anyone infected with SARS-CoV-2, regardless of age or the severity of the initial symptoms of COVID-19. Long COVID/PASC is the continuation or development of new symptoms after three months from the initial SARS-CoV-2 infection, which lasts for at least two months and has no other identifiable cause. Long COVID/PASC occurs in 10-20% of patients infected with SARS-CoV-2. The most common symptoms include fatigue, cognitive impairment (brain fog), and shortness of breath. However, more than 200 symptoms have been reported. No phenotypic or diagnostic biomarkers have been identified for developing long COVID/PASC, which is a multisystem disorder that can present with isolated or combined respiratory, hematological, immunological, cardiovascular, and neuropsychiatric symptoms. There is no cure. Therefore, individualized patient management requires a multidisciplinary clinical approach. Because millions of people have had and continue to have COVID-19, even in the era of vaccination and antiviral therapies, long COVID/PASC is now and will increasingly become a health and economic burden that the world must prepare for. Almost five years from the beginning of the COVID-19 pandemic, this article aims to review what is currently known about long COVID/PASC, the anticipated increasing global health burden, and why there is still an urgent need to identify diagnostic biomarkers and risk factors to improve prevention and treatment.