BACKGROUND: We have previously described a linear increase in thrombotic events since 2020 in an integrated Health consortium in the metropolitan area of Barcelona.

AIM: To describe the characteristics of thrombotic events in relation to COVID-19 vaccination status, SARS-CoV-2 infection, and age.

METHODS: We analyzed anonymized data on infections, hospital admissions, and thrombotic events after March 2020 in the population assigned to the Consorci Sanitari de Terrassa (n=192,651 in 2025). The number of cases of ischemic stroke, ischemic heart disease, retinal vessel thrombosis, and pulmonary thromboembolism were quantified. These were analyzed across different age groups (<60 vs. ≥60 years), COVID-19 vaccination status (vaccinated [V] vs. unvaccinated [UV]), SARS-CoV-2 infection and hospital admission. The dates of infection and thrombotic events were recorded. An odds ratio (OR) was calculated to compare the risk of thrombosis between 2021 and 2024.

RESULTS:

The overall increase in thrombotic events from 2021 to 2024 was 1.20 in vaccinated individuals (V) and 1.81 in non-vaccinated individuals (NoV). The odds ratio (OR) for ischemic stroke was 1.35–3.8 (V vs. NoV) in those aged >60 years, and 1.35–2.0 (V vs. NoV) in those aged <60 years. The OR for ischemic cardiopathy was 1.17–1.75 (V vs. NoV) in individuals aged >60, and 1.6–1.8 (V vs. NoV) in those aged <60. The OR for retinal vessel thrombosis decreased in most groups (OR 0.33–0.75), but vaccinated individuals under 60 years of age showed an OR of 2.5. Pulmonary thromboembolism showed an OR of 0.47–0.87 (V vs. NoV) in individuals aged <60, and 0.90 (V) vs. 3.5 (NoV) in those aged >60.

CONCLUSION: Ischemic stroke and ischemic heart disease exhibited an increased incidence of thrombosis. Potential explanations for this rise, including post-pandemic lifestyle changes, undetected SARS-CoV-2 infections, a growing population without vaccination records, and a more impaired socioeconomic environment, should be explored in future studies.