Recent studies have shown that individuals with long COVID who report persistent symptoms affecting the heart, lungs, brain, and musculoskeletal systems are approximately twice as likely to have SARS-CoV-2 proteins circulating in their blood compared to those without prolonged symptoms. These proteins, including the spike protein of the virus, remain detectable months after the initial infection using ultrasensitive tests like Simoa.

The lingering presence of these viral proteins may be linked to the immune system's overactivation, which can lead to ongoing inflammation and various long COVID symptoms. Commonly reported symptoms include fatigue, brain fog, muscle and joint pain, back pain, headaches, sleep disturbances, loss of smell or taste, and gastrointestinal issues. This ongoing immune response and the detection of viral proteins in the blood suggest that long COVID may be driven by a persistent low-level infection or an autoimmune reaction triggered by the virus.

These findings offer important insights into the biological mechanisms behind long COVID and may pave the way for developing more targeted treatments to address this condition in the future.