Your post says your wife gets out of breath sometimes after a relatively mild COVID infection. That sucks and I'm sorry to hear it, but I'm not sure that rises to the level of dangerous, exactly. Lots of people end up out of breath just from obesity, which is I guess can be considered dangerous in some ways, but most people probably wouldn't actually describe it that way relative to many other medical ailments.
She is a healthy 40 yo who used to exercise far more than me and do yoga multiple times a week. She's fit healthy and active until she was infected with covid. The breathlessness (sometimes accompanied with massively increased heart rate) also registers as very low blood oxygen levels on her meter. This isn't sometimes, this is after any activity. This is also just one of the symptoms she's had - massive fatigue, numbness, migraines (never had them before) - it goes on.
For someone like her to be breathless - is certainly a sign that something serious can happen to those that catch covid. This, while not happening to everyone is getting more attention now: Coronavirus: Thousands say debilitating symptoms last 'for weeks' - BBC News
https://www.bbc.com/news/health-53269391
The common theme on the Slack group she is on, is that these are younger and healthy people, and that their covid was not particularly severe.
She also struggles to concentrate for any length of time, even reading a kids book to the children can be too much for her. There is no way she could work right now, and can't even do much more than supervise the kids for short periods of time - I am very lucky to have a flexible employer.
This appears similar to post viral syndrome or ME - and is happening at far higher levels than seen with our more common viruses like the Cold or Flu - though was also seen in people who caught SARs - it was not questioned that a percentage of those who had SARs were ill n months later, I'm sure in time it won't be for covid too. Just in tne mean time it means people believe the only risk is of death and that it will only affect the old and infirm.
The problem is, and I know you will hate to hear this, is that these sorts of anecdotes may or may not mean anything. Symptoms like that have a long history of turning out to be false alarms. That's the reason medical trials have placebos: health is weird and people can cure themselves or make themselves sick from all kinds of ways that logic dictates shouldn't happen, like 'thinking' themselves into it, or just via random chance.
Does COVID-19 cause breathlessness in a tiny percentage of people who caught it? Possibly, it's a respiratory virus after all. Does it cause loss of concentration? Hmm, maybe, who knows. The body works in mysterious ways. But if it can cause that then more or less any symptom at all is fair game.
Seen another way, do people with wifi sensitivity truly feel headaches when wifi is turned on? They certainly believe they do, their suffering seems to be real, yet we know their self-diagnosis cannot possibly be correct ... at least not without significantly rewriting the laws of physics and biology as we know them.
It may be that your wife should lose the Slack group and see a doctor. The risk is that the collection of symptoms she's reporting (which have no known link with respiratory diseases) actually have another cause and COVID is a distraction. It could be an undiagnosed case of something else that needs attention. We know that COVID is being spuriously linked in the media to all kinds of random conditions and symptoms, and especially when in a community of other sufferers, it's possible for incorrect inferences to be made.
