BACKGROUNDGreece faced particular COVID-19-pandemic-related challenges, due to specific socio-cultural-economic/public-health factors and drastic restrictive policies.OBJECTIVESTo understand trajectories of overall mental and physical health, well-being, emotional states and individual psychopathology in response to pandemic-related restrictive measures within general adult Greek population across the first two pandemic waves.METHODSUsing multiple time-point cross-sectional data from the "Collaborative Outcomes study on Health and Functioning during Infection Times" (COH-FIT), we examined changes in outcomes from retrospective pre-pandemic ratings (T0) to three distinct intra-pandemic time points (lockdown 1: T1, between lockdowns: T2, lockdown 2: T3). Primary outcomes included WHO-5 well-being scores and a composite overall psychopathology "P-score", followed by a wide range of secondary outcomes.RESULTS10,377 participant responses were evaluated, including 2737 representative-matched participants. Statistically significant differences in well-being and overall psychopathology before and after quarantine (T0 vs. T1-T3), as well as across the assessed time frames (T1, T2, and T3) emerged in both samples. Global mental and physical health, individual psychopathology scores (anxiety, depression, PTSD, OCD, panic, mania, mood swings, sleep and concentration problems), emotional states (anger, helplessness, fear of infection, boredom, frustration, loneliness and overall stress scores), BMI and pain scores also showed statistically significant time differences in both samples, with the exemption of self-injury and suicidal attempt scores, showing lower intra-pandemic scores.CONCLUSIONSThis is the largest multi-wave report on well-being, mental and physical health across different pandemic restriction periods in Greece, suggesting a substantial negative effect of lockdowns on most outcomes at least during the acute pandemic waves.