I have. Saw an article in the NY Times last July about a Long Covid study at Yale University Medical Scool. They gave NAC and a prescription medication to those enrolled in the study. Fatigue and brain fog were relieved. I decided to try the amino acid, bought some from Amazon in July. It has helped me so much. I now have energy to walk instead of using a wheelchair. Brain fog is also much less. I am 75, have had LC for over three years. Highly recommend for anyone to try. When I told my internist she was very pleased, said she has another patient who is 70, and will suggest she try. She also said it is safe. Even if it doesn't help, it won't hurt.