Vaccine safety studies of Brucella abortus S19 and S19ΔvjbR in pregnant swine

•Vaccination with Brucella abortus S19 or S19ΔvjbR in pregnant swine did not induce abortion, stillbirths or a reduction in litter size.•Gross and histopathological evaluation did not demonstrate any local or systemic side effect associated with either vaccine.•At the time of the delivery, there was no evidence of the presence of either vaccine strains in the fetuses, placentas or sows.•Both vaccine candidates are safe for use in pregnant swine.