Smallpox vaccination does not elevate systemic levels of prothrombotic proteins associated with ischemic cardiac events

Background. During the recent smallpox vaccination campaigns, ischemic cardiac complications were observed after vaccination. To examine a possible association between the smallpox vaccine and postvaccination ischemic events, we investigated alterations in levels of prothrombotic proteins (plasminogen activator inhibitor type 1 [PAI-1] and soluble CD40 ligand [sCD40L]) in recently vaccinated individuals. Methods. Vaccinia-naive (cohort N; aged 18-32 years) and vaccinia-experienced (cohort E; aged 33-49 years) healthy adults were vaccinated with a 1:5 dilution of the Aventis Pasteur smallpox vaccine. Plasma levels of PAI-1 and sCD40L were measured in 30 subjects (cohort N, n = 15; cohort E, n = 15) at baseline and twice after vaccination (between days 7 and 9 and between days 26 and 30). Results. Baseline mean PAI-1 levels significantly differed between cohorts N and E (P = .04). Within each exposure cohort, mean PAI-1 levels did not significantly change after vaccination. Baseline sCD40L levels did not differ between cohorts N and E. In cohort N, sCD40L levels significantly decreased after vaccination but returned to baseline levels within 1 month. Vaccination did not significantly alter levels of sCD40L in cohort E. Conclusions. Levels of PAI-1 and sCD40L did not significantly increase after smallpox vaccination. Vaccine-induced alterations in levels of these prothrombotic proteins do not appear to play a role in ischemic events observed after smallpox vaccination.