Long COVID across SARS-CoV-2 variants: Clinical features, pathogenesis, and future directions

Abstract

Long coronavirus disease (COVID) is characterized by persistent symptoms following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection and has emerged as a significant health concern. As SARS-CoV-2 evolved from the wild-type strain to the Alpha, Beta, Delta, and Omicron variants, there may be a variant-specific influence on long COVID akin to the acute disease. This review aims to summarize our current knowledge of variant-specific influences in long COVID incidence, symptom profile as well as mechanisms of pathogenesis. We highlight that long COVID incidence may be lower with the Omicron variants. The symptom profile of long COVID may also show some dependence on the different variants, with a reduction in cardiopulmonary symptoms with more recent SARS-CoV-2 variants. This heterogeneity of long COVID may also be related to the variant-specific differences in affecting the immune system, viral persistence, and autoimmunity. However, emerging data also suggest that vaccinations may play a big role in shaping the presentation of long COVID. We also highlight ongoing work on long COVID incidence and symptom profiles in populations infected only by the Omicron variants. This will be beneficial toward more useful disease definitions and the development of effective diagnostic and therapeutic strategies.