The Impact of the COVID-19 Pandemic in Greece, 2020–January 2023: An Analysis Based on National Digital COVID-19 and Vaccination Registries

Background/Objectives: From early 2020, Coronavirus Disease 2019 (COVID-19) pandemic spread rapidly worldwide, bringing unprecedented challenges. It severely disrupted health, social, and financial systems while exacerbating poverty and socioeconomic problems globally. This study aimed to investigate the characteristics and general health status—including age, comorbidities, and COVID-19 vaccination status—of SARS-CoV-2-infected patients as documented in Greek national registries, with a particular emphasis on COVID-19-related mortality. Methods: Anonymized individual-level data were obtained from the national digital registries of COVID-19 patients and vaccinations. Data extraction was initiated on 7 January 2023, and the linked anonymized dataset was provided to the research team on 18 January 2023. The data sets were linked by the e-Government Center for Social Security Services using the Greek social security number (AMKA). Data on comorbidities were estimated by, and extracted from, medicine prescriptions in outpatient settings using the standardized therapeutic prescribing protocol as defined by the Ministry of Health of the Hellenic Republic. Multivariable logistic regression was used to examine factors associated with COVID-19 death. Results: Of 33,740 people who died of COVID-19 infection, 70.0% (23,606) were not vaccinated. Sixty-seven point two percent (18,474) of individuals dying from COVID-19 were 70 years or older and not vaccinated. Hypertension was the most common comorbidity among patients who died from COVID-19 (67.1%). Among the 27,489 recorded COVID-19 deaths in individuals aged 70 years or older, unvaccinated individuals with two comorbidities accounted for 17.6% of deaths, while unvaccinated individuals with three comorbidities accounted for 16.7%. The multivariable analysis showed a much lower risk for people who had received two doses of the COVID-19 vaccine compared to those who are unvaccinated [odds ratio (OR) = 0.35; 95% CI: 0.33–0.36]. The existence of one or more comorbidities increased the risk of death (OR = 1.10; 95% CI: 1.09–1.11). Conclusions: Most COVID-19 fatalities in Greece occurred among unvaccinated individuals over 70 years of age. Mortality among vaccinated individuals was relatively low and was predominantly observed in those with multiple underlying health conditions. Thus, increasing Greece’s vaccination rate and addressing non-communicable diseases could significantly lower future COVID-19 deaths.