The high efficiency of using thermoheliox (inhalation with a high-temperature mixture of helium and oxygen) in the treatment of patients affected by COVID-19 was shown. The dynamics of accumulation of IgG, IgM, and C-reactive protein (CRP) in patients with coronavirus infection in the “working” and control groups was studied experimentally. It was shown that thermoheliox intensifies the synthesis of IgG, IgM, and CRP antibodies, while eliminating the induction period on the kinetic curves of the synthesis of specific antibodies in the IgG form and transfers the synthesis of CRP to a fast phase. The results of experiments confirm the previously obtained data based on the analysis of the kinetic model of the development of coronaviral infection in the human body.