salon[.]com/2022/02/21/long-haulers-may-have-finally-found-relief-in-inexpensive-over-the-counter/
livescience[.]com/antihistamines-to-treat-long-covid-pasc
latimes[.]com/socal/daily-pilot/entertainment/story/2022-02-09/uci-case-report-suggests-antihistamines-may-provide-relief-for-long-covid-sufferers
There's LOADS of COVID research going on, but not much in the way of concrete results published in the major media outlets. Many studies so far are small and too recent to build consensus in the medical community. I could be wrong, but I assume those suffering from long-term COVID [called long-haulers (?)] know about it -- med scientists think there's likely millions of people effected.
A couple of small studies suggest that antihistamines can help long-hauler's symptoms, though they don't know how long you have to keep taking them, and if they just help symptoms or can eventually effect some sort of cure.
Personally I was a bit leery of taking an OTC pharma product long term [potentially for years], so I went looking for natural alternatives. I found & tried Stinging Nettle Leaf [NOT root], taking 2 capsules twice daily, and it's Really helped, which is why I'm posting this sort of PSA. After all, antihistamines are readily available, cheap, and considered safe, so IMHO, if you're a long-hauler, it's well worth a try.
healthline[.]com/health/allergies/best-natural-antihistamines