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.