Q: Has anyone treated Covid-19 with hydrotherapy?

Yes!  While there has not yet been a randomized controlled study looking at the efficacy of hydrotherapy in the outpatient and inpatient setting, I know of several centers that are employing hydrotherapy and studying its effects.  There is good reason to believe that such an intervention could work but again nothing is 100% effective.  When employed for the influenza pandemic in 1918 at Adventist Sanitariums in the Northeast, it was more effective when started early and did not work in 100% of the cases.  Here are some references with regard to hydrotherapy.[1, 2, 3]

Response by Roger Seheult, MD, Associate Clinical Professor at the University of California, Riverside School of Medicine and  Assistant Clinical Professor at the School of Medicine and Allied Health at Loma Linda University