A study with sample size of 4?
“The presentation of four individual case descriptions does not allow for general conclusions to be made about the therapeutic effect of transcutaneous nicotine administration in post-COVD-19 syndrome; this would require double-blinded, randomized studies. Due to the minimal therapeutic intervention, studies such as these have the potential to be carried out rather easily. Due to the lack of blinding, the author believes that the psychosomatic component, which other authors suspect to be a central component of long-haul COVID (Stengel et al. 2021), cannot be safely ruled out as part of the therapeutic effect. However, no symptom-related relapses were observed in a follow-up telephone consultation with the patients three to six months post-intervention.”