Open issues around COVID-19 and work: Lessons learned from the literature and the European ORCHESTRA multicentric study on health workers.

Introduction SARS-CoV-2 had enormous impact on occupational health, particularly in healthcare. In Italy, nearly 500,000 health workers (HW) were infected. A few questions remain to be addressed by occupational medicine, e.g. relationship between humoral and cellular immunity, impact of breakthrough infections, comorbidities, variants of concerns; long COVID; compensation; targeted risk assessment and health surveillance. Materials and Methods Considerations from literature and data from the European ORCHESTRA multicentric project, involving about 63,500 HW from 14 European countries with > 50 papers published. Results Vaccines contained the pandemic, even though breakthrough infections (cumulative incidence < 1.5% in fully vaccinated HW, 20.6% in boosted) and reinfections occurred, mainly due to variants of concern and to some determinants, including comorbidity and immunological status. Moreover, at least 65 million individuals worldwide are estimated to have long COVID, occurring in at least 10% of SARS-CoV-2 infections, with > 200 symptoms/signs. The study of immune response is still crucial. Humoral response is relevant in > 99.3% of vaccinated HW, with decreasing temporal trends, related to age, previous infections, vaccine type. Little is known about cellular immunity and its interaction with humoral response, which we are currently studying on about 300 HW. Conclusions In occupational settings, risk assessment and health surveillance protocols should consider the risk factors for breakthrough and reinfections and risk profiles for vulnerable workers with comorbidities and predisposing factors for long COVID. The new vaccine campaigns should be concurrent with the flu vaccine; health surveillance program should consider return-to-work policies; compensation criteria for occupationally infected workers should be harmonized.