Our approach to Long Covid is to treat it as we would our Chronic Fatigue Syndromes. 
We have had significant success with replacing the gut microbiome in our Chronic Fatigue population, many of them had Chronic Fatigue for decades, and we have published on this. 
Because of the Covid-19 Pandemic, we have had to switch from Faecal Microbiome Transplantation (FMT) to Gut Flora Replacement Therapy (GFRT), which is very much cheaper than donor-derived, laboratory-processed Implants, and we have published on this. 
We have had significant success with this in treating Long Covid, and indeed have had more success than we had with Faecal Microbiome Transplantation in treating Chronic Fatigue Syndrome.
There is evidence that the microbiome is abnormal in Covid-19  
We also use High Dose Intravenous Vitamin C and Ozone Autohaemotherapy for Long Covid, with significant success. These are all safe treatments, and they are all available at The Dove Clinic for Integrated Medicine www.doveclinic.com Any questions about Long Covid and the treatments we offer can be directed via firstname.lastname@example.org.
- Karl J Morten, Eleonora Staines-Urias, Julian N Kenyon – Potential clinical usefulness of gut microbiome testing in a variety of clinical conditionshttps://doi.org/10.1016/j.humic.2018.08.003
- J.N. Kenyon, Shelly Coe, Hooshang Izadi – A retrospective outcome study of 42 patients with Chronic Fatigue Syndrome, 30 of whom had Irritable Bowel Syndrome. Half were treated with approaches, and half were treated with Faecal Microbiome Transplantation – https://doi.org/10.1016/j.humic.2019.100061
- Julian N Kenyon – Comparing the Results from Faecal Microbiome Transplantation (FMT) and Gut Flora Replacement Therapy (GFRT) using 16s Mrna Microbiome Mapping – yon ISSN 2692-5877 DOI: 10.46998/IJCMCR.2021.11.000253
- Heenam Stanley Kim- Do an Altered Gut Microbiota and an Associated Leaky Gut Affect COVID-19 Severity? DOI: 10.1128/mBio.03022-20
- Yeoh YK, Zuo T, Lui GC, et al Gut microbiota composition reflects disease severity and dysfunctional immune responses in patients with COVID-19 Gut 2021;70:698-706.