Who Still Pays the Price of SARS-CoV-2 in the Vaccination Era? Evidence from Primary Healthcare in Greece

Background: Understanding how demographic and clinical factors influence SARS-CoV-2 infection patterns, vaccination uptake and disease outcomes in community settings is essential for effective primary care-based public health planning. Objectives: This study aimed to investigate the distribution of SARS-CoV-2 infections among adults attending Primary Healthcare (PHC) facilities in Giannitsa, Greece, from 2020 to 2024, and to examine associations between demographic and clinical characteristics, vaccination category and disease outcomes. Methods: A retrospective analysis was conducted using data from the National Registry of Patients with COVID-19. The study included 1144 adults diagnosed with SARS-CoV-2 at PHC facilities from 19 November 2020 to 3 October 2024; all cases included in the present analysis had been confirmed by rapid antigen testing. Variables included age, gender, residence, registry-recorded underlying medical conditions, vaccination category, seasonality and clinical outcome. Results: Significant shifts in case distribution were observed across time, with younger adults predominating in 2020–2022 and older adults (61–90 years) in 2023–2024 (p < 0.001). Winter months showed higher case incidence overall (p < 0.001). Vaccination coverage increased annually, reaching 84.8% in 2024 (p < 0.001). Hospitalization/death occurred in 1.7% of patients and was strongly associated with age ≥61 years (6.0% vs. 0.3%), the presence of at least one registry-recorded underlying medical condition (9.2% vs. 0.9%) and vaccination category; specifically, hospitalization/death occurred in 10.4% of individuals diagnosed during the pre-vaccine period, 2.3% of unvaccinated individuals during the vaccination era and 0.9% of vaccinated individuals (all p < 0.001). Conclusions: Older age, underlying medical conditions and a lack of vaccination were key predictors of worse outcomes. The findings underscore the importance of strengthening vaccination outreach and targeted PHC interventions, particularly for high-risk and rural populations.