The features of professional pedagogical activity increase the likelihood of teachers' health decline. However, having the resources to cope with difficulties can mitigate the tension caused by occupational stress. In recent years, many authors have noted that chronic fatigue syndrome is a multi-causal pathology and many factors affect its development, one of which is high stress load. The stress load includes both the strengthening of the requirements for the professional activity of the teacher, and the complication of the external situation, an increase in the level of its uncertainty due to the pandemic of COVID-19 and self-isolation. This article considers the issues of professional health of teachers and the risk of developing chronic fatigue syndrome in the process of introducing new educational technologies during a pandemic. The study was conducted in two stages: shortly before the introduction of distance learning in general education schools in connection with the transition to self-isolation due to the COVID-19 pandemic and after the introduction of distance learning. The presence of chronic fatigue syndrome was determined using The Fatigue Assessment Scale (FAS) (H. J. Michielsen, adapted by L. F. Bikbulatova) and the questionnaire "Criteria for chronic fatigue syndrome" (S. G. Komarov). Methods of mathematical statistics: The Pearson's chi-squared test and the Mann-Whitney U test. Statistical data processing was carried out using the SPSS-20.0 program. It has been established that the introduction of a distance learning format in general education schools is a stressful factor for teachers. After the introduction of the distance learning format, a significant part of the teachers was found to have pathological fatigue, as well as a high risk of developing chronic fatigue syndrome.