Abstract A high percentage of those who develop SARS-CoV-2 infection have post-Covid syndrome. Health surveillance in the workplace must identify workers who develop this syndrome to prepare the appropriate support measures. All workers who developed Covid in a sample of 1378 workers exposed to biohazards were asked to report post-Covid symptoms and to complete questionnaires to measure occupational stress, sleep quality, fatigue, work ability, and mental health. 164 workers had Covid and 115 of these (70%) had symptoms one month after the acute phase. The frequency of the post-Covid syndrome was higher in workers with more severe or longer-lasting acute forms and in females than in males. In 80% of cases, the pattern of symptoms included the association of anosmia and dysgeusia or of weakness, fatigability, and tiredness. In 20% of cases these symptoms were associated with dyspnea, tachycardia, headache, sleep disturbances, anxiety, and muscle aches. In 80% of cases, the pattern of symptoms included the association of anosmia and dysgeusia or of weakness, fatigability, and tiredness. In 20% of cases these symptoms were associated with dyspnea, tachycardia, headache, sleep disturbances, anxiety, and muscle aches. 11% of those who contracted the infection reported worsening of the morbid conditions from which they had previously suffered; these symptoms were still present six months after the acute phase. Workers with post-Covid were found to have poorer quality sleep, increased fatigue, anxiety, depression, and decreased work ability compared with workers whose symptoms had rapidly disappeared. A large percentage of workers, after an infection that might also be mild or modest, developed persistent symptoms that compromise their working capacity and quality of life. Considering the number of Covid cases in the world, it can be estimated that between 42 and 69 million people suffer from post-Covid syndrome. Key messages • A large percentage of workers suffer from post-Covid syndrome and require support in the workplace. • We can estimate that 42-69 million people worldwide suffer from post-Covid syndrome.