Background: Protection of refugees, migrants, and asylum seekers living in open hosting camps (HCs) and reception and identification centers (RICs) has been a priority since the beginning of the COVID-19 pandemic. We present the epidemiological data of COVID-19 infection in HCs/RICs in Greece from February 2020 to May 2021, before the initiation of the onsite vaccinations.Methods: Case confirmation was performed by rapid antigenic test and/or RT-PCR. Data were retrieved from the National COVID-19 registry. The notification rate by type of accommodation facility, by sex and ethnicity and the mean age of cases, were calculated for HCs, RICs and general population. Data on clinical manifestations, and disease severity (admissions to intensive care unit (ICU) / case fatality rate) were analysed.Results: Of the 397,497 recorded domestic COVID-19 infection cases, 2,609 (0.7%) regarded HCs/RICs; of them 1,566 (60%) were identified in 27 HCs and 1,043 (40%) in six RICs. The notification rate was 542 and 380 cases per 10,000 population in HCs/RICs and the general population, respectively (p-value<0.001).Up to February 2021 the occurrence of cases in HCs/RICs did not follow the occurrence of cases in the general population. After March 2021 the course of the outbreak in HCs/RICs and the general population was similar.The median age of cases in HCs/RICs and the general population was 27 (range:0-81) and 44 (range:0-106), respectively (p<0.001). Twenty-four different ethnicities were reported among migrant cases; 51% were from Afghanistan, 13% from Syria, 6% from Kongo and 5% from Somalia.Overall, 48% and 80% of cases, respectively in HCs/RICs and the general population were symptomatic (p<0.001). Five (0.2%) cases in HCs/RICs were admitted to the ICU compared to 10,426 cases (3.0%) in the general population (p-value <0.001). Case fatality rate was 3% in the general population and 0.08% in HCs/RICs (p-value <0.001).Conclusion: Recorded COVID-19 infections were less severe in migrants living at HCs/RICs than the general population, however, the number of identified cases was high and measures for the prevention of transmission should be strengthened.