This article will discuss the causes of long COVID.
Since the start of the COVID-19 pandemic, there has been a rise in cases of long COVID. Long COVID is a set of symptoms that persistent longer than acute infection. It is difficult to define when symptoms become long COVID. In general, symptoms that persist longer than 4-12 weeks without any other obvious cause could be long COVID.
What causes long COVID?
No definite cause has yet been identified, but many theories exist. There have been many links between symptoms of long COVID and those of myalgic encephalomyelitis (ME) or chronic fatigue syndrome (CFS).
- Post-viral alterations in the immune system
- Reactivation of viruses that have been associated with ME/CFS such as Ebstein-Barr virus (EBV) and human herpesvirus 6 (HHV-6)
- Ongoing viral activity within body tissues
- Damage to the lining of blood vessels
- Leading to blood clots
- Affects the flow of blood to areas of the brain, heart and lungs
- Inflammation of nerve fibres (making signals take longer to travel)
- Low cortisol levels- cortisol is a stress hormone that changes in concentration in the body depending on the time of day. It helps your body process sugar, maintain a normal blood pressure and helps reduce inflammation.
- Impaired metabolism of fat stores
There is also evidence that women who ovulate may have worse symptoms in the week prior to and during menstruation.
What next?
More research is required to understand long COVID. When we have a greater understanding of the underlying processes that lead to long COVID, we can begin to work out how best to identify people affected, determine ways to prevent it, and finally find good evidence-based treatments.
