Is chronic stress the invisible factor behind Long COVID?

When it comes to a COVID-19 prognosis, it has become abundantly clear that ‘underlying health conditions’ are the most important factors associated with our outcome. Pre-existing heart conditions, type 2 diabetes and obesity are just some of the factors which make us more likely to suffer complications. This makes sense - at a very basic level these conditions create long-standing inflammation in the body, leaving many unable to fight off the additional inflammation brought on by the virus, and therefore more vulnerable to severe disease (1). In other words, how well you weather the fight depends on the status of your battlefield.

So how do we explain those suffering with “long-COVID” who claim, not only to have no underlying conditions, but to be incredibly fit and healthy? Hospital doctors who frequented the gym 4 times a week, nutritionists who drank green juices every day or yoga teachers who practice mind-body connection? I believe that there is one massive elephant in the room that no-one seems to be talking about: chronic stress. I suspect it is the key factor which sits between an ‘otherwise healthy’ person and Long-COVID.

First, let’s start with what Long-COVID is...

Although it feels new, it is actually a form of ‘post-viral fatigue syndrome’ (PVFS) which we have seen before in those suffering with Epstein-Barr, Influenza, Glandular Fever and after other major pandemics including 1918 Spanish Influenza and 2003 SARs (2,3). According to the World Health Organisation, post viral fatigue syndrome is…

“…a complex medical condition, characterised by long-term fatigue and other symptoms. These symptoms are to such a degree that they limit a person’s ability to carry out ordinary daily activities”

There is a clear resemblance to Chronic Fatigue Syndrome (CFS)/Myalgic Encephalomyelitis (ME) in that, conventional blood lab results are normal, but symptoms are very real, very debilitating and wide-ranging. Severe fatigue and exhaustion is often coupled with muscle and joint pain, headaches, brain fog, gastrointestinal issues, sleep and mood disorders (3).

So, what’s actually going on in the body?

A major school of thought is that post viral syndrome is the result of an overactive immune system which fails to switch off once it’s fought off the infection, leading to an increase in chemicals called cytokines. These chemicals create inflammation and therefore produce symptoms of illness (5). Of particular note is the highly aggressive cytokines IL6 and 7 which can cross the blood brain barrier and lead to a build-up of inflammatory toxins in the brain. This is why so many people suffer with neurological symptoms such as fatigue, confusion and low mood.

What is the role of stress?

Experiencing a stressful situation leads to the brain activating stress hormones which communicate with the parts of the body that need to be ready for ‘fight or flight’. Blood gets pumped to the brain for alertness and to muscles for combat, pupils dilate for better vision and glucose pours into the bloodstream for energy. These hormones also send messages to switch off the bodily functions we don’t require, including immune function. Why would we need to tackle an infection while we are fighting for our lives?

When stress is prolonged or chronic, it can weaken our innate immunity, creating challenge for our body when it experiences an infection (4). It is the job of our innate immune system to act as first line of defence by recognising and immediately acting on an invading pathogen (6). Our adaptive immune system which has evolved as we have, takes several days to mount a defence and is highly aggressive (6). So when the innate immune system is suppressed and less able to fight the pathogen, not only is the infection able to do more damage, the adaptive immune system is left feeling as though it has to overreact with aggressive chemicals (such as IL6 and 7) which kill the virus, but leave significant inflammation in their path (5).

So, whilst a healthy person may experience the effects of their immune system working via unpleasant symptoms, they will be able to recover from those symptoms swiftly, because their innate immune system has acted effectively and their inflammation response is appropriate. When we are chronically stressed, we may have had to spend longer fighting the infection, meaning that more damage has been done, the effects from the adaptive immune system are more severe, and we are also depleted, leaving us much less able to recover from the the inflammation. It’s no wonder that we are left with debilitating, long lasting symptoms.

Where do we go from here?

I believe it’s critical that we understand just how insidious stress is. Low level stressors are everywhere, from the amount of information we consume day to day, to the continual comparisons we make on social media, to the expectation to be always-on at work. The effects of stress build in the body over time, usually without us knowing. Perhaps most worryingly, our culture glorifies stress. It’s seen as a mark of success to be busy, always on-the-go, with never enough time to sleep.