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Evaluation Video

Oral Presentation

Session: COVID-19: Now and Later

DARWIN EU® - Risk of Thromboembolic Events Associated With COVID-19 During the Omicron Period, and SARS-CoV-2 Vaccination

Wednesday, August 28, 2024
2:15 PM – 2:30 PM CEST
Location: Conv Hall I D
Background: Evidence from earlier waves of the pandemic showed that COVID-19 patients are at increased risk of venous and arterial thromboembolic (VTE, ATE) events. Understanding these risks during the Omicron period, especially in relation to prior COVID-19 infection and/or SARS-CoV-2 vaccination, is crucial.

Objectives: To contextualize the incidence of thromboembolic events among patients with COVID-19 during the Omicron period and individuals who received SARS-CoV-2 vaccination.

Methods: We conducted a population-level cohort study using electronic health records from the UK (CPRD GOLD), the Netherlands (IPCI), and Germany (IQVIA DA). We included the pre-pandemic cohort from 2017-2019, people with COVID-19 when Omicron was dominant (“COVID-19” cohort), and people vaccinated against SARS-CoV-2. Incidence rates of VTE and ATE were estimated among the general population and within 30-, 60-, 90-, and 180-days post-infection or vaccination. Crude incidence rate ratios (IRR) and age-sex standardized incidence rate ratios (SIR) were calculated relative to the general population. Analyses were stratified by prior COVID-19 infection, SARS-CoV-2 vaccination.

Results: A total of 1,275,141 individuals with COVID-19 infection during the Omicron period were included(CPRD: 248,847, IPCI: 330,200, IQVIA DA: 696,094). The vaccinated cohort included 4,342,167 individual who received at least one dose of a COVID-19 vaccine (CPRD: 2,374,109, IPCI: 656,664, IQVIA DA Germany: 1,311,394).
Crude IRRs varied between age, sex, infection history, and vaccination status within database. Compared to the background population, the COVID-19 cohort showed higher SIRs for both ATE and VTE, which persisted up to 180 days after infected with Omicron variant. In CPRD, patients who were unvaccinated, or received two or three doses of vaccines had increased SIR for VTE. An increased SIR of ATE was observed among people who received three doses of vaccines in the CPRD data, and unvaccinated in the IPCI data.
There were increased SIRs of ATE within 60-, 90-, and 180 days after receiving a first (e.g. SIR within 60 days: 1.12 [95%CI: 1.01-1.26] in CPRD) or second dose (1.14 [1.02-1.28] in CPRD; 1.31 [1.06-1.61] in IPCI) of ChAdOx1 vaccine. We observed increased SIR of VTE among within 90 or 180 days after first dose ChAdOx1 but not in shorter period (SIR within 30 days: 1.20 [0.95-1.54]; 180 days:1.30 [1.12-1.52 in CPRD). No increased SIR of VTE were seen in other brand-dose stratification.

Conclusions: There were increased SIRs of ATE and VTE events after infection with Omicron variant. People who received a first or second dose ChAdOx1 vaccine showed higher SIR of ATE when using a longer follow-up window. However, indirect standardization did not account for residual confounding other than age and sex.