In a 12-month cohort follow-up study of 2435 children vaccinated in 2007 by Statens Serum Institute BCG strain (BCG SSI, 17.8% had an adverse event (AE): erythema 12.4%, induration 12.2%, abscesses 2.5%, ulceration 0.9%, lymphadenitis 0.1%. The factors associated with a lower risk of AE were: age at vaccination <1 year compared to age >1 year (OR=0.35 [0.2-0.6] for age <28 days, 0.29 [0.2-0.42] for age 29 days to 2 months, and 0.53 [0.37-0.74] for age 3-11 months), a visible papule (OR=0.48 [0.36-0.63]), and a low vaccine dose (OR=0.42 [0.31-0.58]). AE to BCG SSI vaccination were frequent but rarely severe.