May not be relevant to your type of LC here's my story.
DH had intermittent long COVID. The first bought was nine weeks of being bed bound, breathless, foggy, weak and exhausted. Every time he caught a cold it was like is immune system seized up and sent him crashing again for 2-5 weeks at a time. In the 18months after his first COVID infection (after 2 vaccinations btw) he was bed bound for 20 weeks. He was hospitalised twice as the GP was so concerned.
I was struggling of course, we had two very young children, was working and holding my breath everytime anyone got a sniffle in case it set it all off again, I was getting recurrent boughts of tonsillitis (I think from stress). So I was desperate for a solution and research research researched.
At that point in time there wasn't much research yet but there was some and I put together a list of everything that showed promise. Vitamin d, one of the B vitamins, zinc, pro and pre-biotics, fermented food.
Then went about gathering all this stuff to stuff it into DH.
I was in Sainsbury's one day looking for more stuff (kimchi and kefir) and happened to look at the probiotic yoghurt section and lo and behold, the aptimel 'immune support' had nearly all of the stuff on my list. DH started taking one a day and.....just...stopped getting ill.
Now I'm a rational person, I always considered those yogurts quackery. It's of course possible this is a big coincidence and he just got better on his own. Maybe he was just low in one of these compounds and we were unaware and now his levels have stabilised, I don't know, but I do tell this story just in case it helps someone. (Other brands available I'm sure).