Causes of long COVID

Apart from being down to reactivating dormant viruses, long COVID in some people might be an inflammatory condition whereby the immune system remains activated long after the infection has passed and targets the wrong tissues. Nathalie MacDermott is in the fairly rare position of experiencing what it’s like to have long COVID as well as being an infectious diseases doctor. She thinks an inflammatory reaction against the wrong tissues might be part of the story for her…

Natalie - Nothing is definite, but I certainly have some kind of spinal cord damage or dysfunction related to COVID. I think some of it could have been the direct effect of the virus at the time when I was unwell and maybe some lingering events thereafter. But my illness certainly in the first year to 18 months was somewhat progressive, and that wouldn't really be explained necessarily by the direct effects of the virus. You know, during the very acute illness that I had with COVID, I think some people think there's virus lingering in the body. I'm not sure that that would be the case for, for me. I think maybe the virus has triggered my immune system to mis-recognize some of my own cells in my body. And so my body's created antibodies to those cells and is then attacking elements of my host cells. And particularly in my case, nerve cells and causing some kind of ongoing damage or dysfunction of those cells.

I suppose the other possibility, and there's some data to support what I just said, there's some early data to support the possibility that, so when you're first infected and your immune system is interacting with the virus, it produces these pro-inflammatory chemicals that we call cytokines, and these can trigger inflammation within the body. So I think the other possibility is that one of those chemicals were triggered at the time that I had acute COVID and they caused some damage, but for some reason they may also be lingering in my body. Whether that's because I've got these antibodies that are mis-recognizing my own cells and that are triggering them, or whether that's just because there's some kind of persistent inflammatory trigger in my body that's, that's constantly resulting in some of these chemicals being secreted and those chemicals themselves can cause damage to cells and inflammation. I guess those are the three things that I'm kind of considering when it comes to myself. As you said, I think there is a huge variety in the symptoms and presentations of post-COVID problems that we sort of term long covid, but that's very much a big umbrella term for what's probably several different pathologies going on in different people's bodies.