How Acute & Long COVID Impacts Dive Safety?

By Dennis Guichard

Coronaviruses are nothing new... they are families of viruses that have been infecting humans and animals separately for millennia. Four coronaviruses are endemic to humans, typically infecting the upper respiratory tract and causing what we know as the 'common cold' - not to be confused with the seasonal 'flu', which is something entirely different again, caused by various strains of an influenza virus rather than a Coronaviridae virus.

In just the past two decades, however, three of what are referred to as 'zoonotic' coronaviruses have unusually transferred from animal infection to humans (SARS-COV-1, MERS-COV, and the current SARS COV-2). It is these that have been particularly causing chaos to human health.

There is a common misconception, perhaps quite understandably driven by covid-fatigue and our shared desire to wish the virus away, that the new Omicron virus is 'just the common cold'. Still, unfortunately, the systemic damage caused within our bodies by this zoonotic coronavirus is quite different pathologically. It has many concerns for us in the recreational, commercial, and saturation diving industries.

Like many of us, I'm sure I've lived the last two and a half years or so in absolute fear of SARS-COV-2. I've lost more friends than I bear to think about to the virus and have lived in near-isolation, focussing on eating a protective, nutritious diet and adhering to all the recommended sanitisation protocols, just trying to keep myself safe from getting it. But a few weeks ago, it ultimately got me anyway. I don't quite know whether to be relieved or devastated. Still, there is undoubtedly a level of emotional trauma involved as much as the physiological.

Currently trying to nurse myself now back to total health, I find myself trawling through all the medical portals of published science, trying to deeply understand quite how the various mutations of the virus affect us as divers and quite when might be a safe point for me to get back into the water diving and back into the chamber working as a hyperbaric technologist doing oxygen therapy with patients. What I've found is that there is minimal consensus among the various dive associations worldwide as to when might be a safe point for a return to diving, but to be fair, the virus has also been mutating and changing its physiological impact on our various bodily organs so rapidly that it's been near impossible for science to keep up.

Much of the current scientific literature is understandably based on deep research into thebehaviourisms and pathophysiology of the Alpha, Beta, Gamma, and Delta lineage of the viruses form,

but what has now emerged in the recent six months or so is an entirely new strain of the coronavirus that is structured and behaves quite unlike any of the others. It is so different that there are elements of the scientific community already talking about identifying Omicron as SARS-COV-3 or Covid-21 because it is unique.

Scientists aren't even sure where Omicron came from, as it is not a derivative mutation of Delta or its Covid-19 predecessors. There is conjecture that it perhaps evolved out of some animal yet again possibly connected to the original virus, but it is indeed unique. The positive with it, if we can call it a positive, is that Omicron has crowded out the alternative Delta strain of the virus and now dominates worldwide.

But even Omicron is evolving so rapidly that it must be nearly impossible to keep up with. We initially seemed to have two separate strains of it, named BA.1 and BA.2, although a (relatively rare occurring) BA.3 developed with some shared mutation similarities to both BA.1 and BA.2, whereas BA.2 seemed to very quickly mutate into the version BA.4 and then BA.5 which are most prevalent now here in South Africa but which have also been identified extensively worldwide.

These latest versions are thought to almost be the 'perfect' coronavirus as they have developed their connective spike proteins to be an almost perfect match to the ACE2(Angiotensin Converting Enzyme 2) receptors that we have on our own eukaryotic cells (cells containing a nucleus which the virus needs to replicate itself and spread). It is thus, again perhaps positively, thought that coronaviruses cannot possibly become any more infectious as they are now at the peak 'perfection' of how they attach to our cells.

Whereas the earlier versions of Covid-19 caused havoc to our lungs, Omicron is less likely to. Delta and the likes needed a particular cellular protease enzyme, known as TMPRSS2, for it to penetrate our cells to reproduce and spread... and that enzyme is found abundantly in our lower respiratory system in the deep recesses of our lungs and alveoli. Once the virus got into our cells and our own immune response system recognised it as being there, our bodies flooded the alveoli with antibodies and cytokines, trying to suppress the infection. Our inflammatory response, however, often had catastrophic outcomes for many, and divers that insult our lungs may leave us with bullae and tissue scarring that can be detrimental to our safety whilst diving.

But Covid-19 doesn't just give us a pulmonary insult. It also gets into our bloodstream and causes damage to the endothelial lining of our entire cardiovascular system, a critical interface for how inert gasses are absorbed and

But then Omicron is also different to the Delta lineage viruses in that it doesn't need TMPRSS2 to access our cells... it has evolved itself to much more efficiently gain access to our upper respiratory paranasal cells through a process called endocytosis positively resulting in a 'weaker' insult than the Delta TMPRSS2 binding mechanism. Omicron also doesn't cause individual cells to fuse together (a process known as syncytia) as Delta did to our lung tissues. Omicron has evolved, however, to have some of the same spike proteins as the 'common cold' virus, which is why it has also partially become so 'successfully' infectious. It perhaps is also where the convenient dismissing confusion comes from about the severity of Omicron.

So, all in all, Omicron can get into our bodies in a seemingly less destructive and often asymptomatic manner and can sneak into cells without our immune defence system often realising it is there, but that's not for a moment to think that it

doesn't still destroy once it's snuck in the back door. Assessment of commercial divers through British research has shown that as many as 40-50% can actually be Covid positive but still be completely asymptomatic, yet often show negative pulmonary changes on CT scans.

By all accounts, Omicron causes fewer hospitalisations and deaths than the Delta predecessors. Hence, it 'seems' to be 'milder'. Still, the concern for us is not necessarily whether the virus is symptomatic, whether it gives us a direct pulmonary insult. Still, quite what damage it might be causing internally that might risk our safety in diving.

Research reveals two pathways of concern... one, that the virus has been shown to impact our colon microbiome negatively, and secondly, how the virus spike protein triggers what is known as amyloid clotting systematically within our cardiovascular systems. This amyloid micro-clotting (amazingly first identified

by a South African researcher Resia Pretorius at the University of Stellenbosch) is also thought to be central to what causes the long-covid effects that so many people are finding they're struggling with.

Besides accessing our eukaryotic cells and causing direct destruction, Covid is also known to act like a bacteriophage, infecting bacteria in our gastrointestinal tract and through to our colon microbiome. When the bacteria sense the presence of any virus, they release toxins to try to destroy it, modifying its surface properties which ironically permits the virus to gain access to the bacteria whereby its RNA can either combine with or break down the host bacteria.

In ongoing research by Dr Sabine Hazan in the USA, the covid virus thrives in faecal bacterial samples of patients up to a year after the infection was thought to have passed symptomatically. It has been shown that there is commonly a decrease

in beneficial bacteria and an increase in pathogenic bacteria because of covid harbouring in our colons. In almost all patients who suffer insult from the virus, there is shown to be an initial lack of destruction, specifically of Bifidobacterium.

Our gut health is central to the effective functioning and well-being of almost every other function and organ in our body. Bifidobacterium is key to much of that. The bacterial changes influence a decrease in lipid (fat) metabolism, a decrease in glycan biosynthesis (important for maintaining tissue structure, porosity, and integrity), and a decrease in metabolism pathways. Interference with the microbiome also shows a resultant enhanced carbohydrate metabolism. This microbiome dysbiosis may also concern saturation teams where optimised nutrition and energy balance are critical for divers' well-being.

Coronaviruses can impact any organ containing the binding enzyme ACE2, found throughout our respiratory system, gastrointestinal tract, liver and gallbladder, pancreas, kidney and bladder, male testis, female fallopian tube and placenta, etc.

The potential presence of amyloid clotting and hyperactivated platelets are of tremendous concern to us as divers because these persistent micro clots are resistant to the body's own fibrinolytic processes (which usually break down and remove clots). These clots may be problematic because they could also interfere with the solubility of inert gasses going into and out of our tissues in decompression, and again also provide ideal seeds for the formation and aggregation of bubbles that might otherwise not have formed on our typical dive profile. General pathology blood tests do not pick the micro clots because the inflammatory markers are trapped within the micro clots.

Diving physicians worldwide are doing their best trying to grasp quite what risk these endlessly mutating viruses might pose to us in diving. The Delta lineage viruses risked causing chronic pulmonary damage, whilst all of the viruses, including Omicron, still risk potential harm to our cardiovascular, central nervous system, and metabolic processes. The most recent guidance for even mild or asymptomatic infection seems to vary between a week to 3-months respite for a 'safe' return to diving. The truth, though, is that we're each very bio-individual, and what guidance is 'right' for one might not be so for another.

The DAN' Return to Diving' guidance follows the grading system offered via the Diving and Hyperbaric Medicine publications. It seems the most reasonable and widely used worldwide. Ultimately the best advice has always been to obtain a full diving medical from a respected Diving Physician, which is certainly what I will do for myself once I feel entirely asymptomatic again.