Some patients develop Post-acute COVID-19 syndrome, in which they experience persistent symptoms after recovering from the acute phase of COVID-19 infection. This syndrome may be more significant in patients with systemic autoimmune rheumatic diseases (SARDs) who have been suffering from several symptoms associated to SARDs, such as myalgia, fatigue, and general pains. The transcranial direct current stimulation (tDCS) technique has been frequent, for example, to relieve fatigue and general pains in general population. However, to date, there are no studies evaluating this technique in ARD patients with post-acute COVID-19; therefore, the main objective of the opened study is to evaluate the safety and efficacy of the application of acute tDCS in ARD patients with post-acute COVID-19.