In December 2019, SARS-CoV-2 was identified as the viral cause of acute COVID-19 infections. However, extensive testing by the NIH has been unable to pinpoint the underlying cause of long COVID symptoms in most cases. One reason that long COVID is difficult to identify is that many conditions are similar to those of other disorders or conditions.
The etiology of long COVID has not been identified. Although the basic disease pathogenesis remains to be established, several hypotheses have been proposed.6
1. Chronic inflammation triggered by a persistent virus or viral remnants in tissues, e.g., viral RNA or protein.
2. Autoimmunity
3. Dysregulated gut microbiome
4. Dysbiosis and latent reactivation of viruses, e.g., Epstein-Barr virus.
Women tend to develop long COVID symptoms more frequently than men. According to the CDC, African Americans have a significantly higher risk of contracting an acute SARS-CoV-2 infection with an associated increase in the manifestation of long COVID. Approximately 5% to 30% of patients with mild or asymptomatic infections who develop symptoms within three months of acute infection are diagnosed with long COVID. Older patients and patients with severe medical conditions are the most likely to experience lingering COVID-19 symptoms.
