title: Risk of lymphoma and leukaemia after bacille Calmette-Guérin and smallpox vaccination: a Danish case-cohort study.
abstract: Vaccines may have non-specific effects as suggested mainly in mortality studies from low-income countries. The objective was to examine the effects of BCG and smallpox vaccinations on subsequent risk of lymphoma and leukaemia in a Danish population experiencing rapid out-phasing of these vaccines. In a background cohort (N=47,622) from the Copenhagen School Health Records Register, cases of leukaemia (N=20) and lymphoma (N=51) were identified through the Danish Cancer Registry. The vaccination status of the cases was compared with the vaccination status of a 5% random sample (N=2073) of the background cohort and analysed in a case-cohort design. BCG vaccination reduced the risk of lymphomas (HR=0.49 (95% CI: 0.26-0.93)), whereas smallpox vaccination did not (HR=1.32 (0.56-3.08)). With the small number of leukaemia cases, the analysis of leukaemia had limited power (BCG vaccination HR=0.81 (0.31-2.16); smallpox vaccination HR=1.32 (0.49-3.53)). The present study with very reliable vaccine history information indicates a beneficial effect of BCG vaccination on the risk of lymphomas.
authors.affiliation: Institute of Preventive Medicine, Copenhagen University Hospital, Centre for Health and Society, Øster Søgade 18, 1st Floor, DK-1357 Copenhagen K, Denmark. mvm@ssi.dk
authors.forename: Marie
authors.initials: M
authors.lastname: Villumsen
authors.forename: Signe
authors.initials: S
authors.lastname: Sørup
authors.forename: Tine
authors.initials: T
authors.lastname: Jess
authors.forename: Henrik
authors.initials: H
authors.lastname: Ravn
authors.forename: Thomas
authors.initials: T
authors.lastname: Relander
authors.forename: Jennifer L
authors.initials: JL
authors.lastname: Baker
authors.forename: Christine Stabell
authors.initials: CS
authors.lastname: Benn
authors.forename: Thorkild I A
authors.initials: TI
authors.lastname: Sørensen
authors.forename: Peter
authors.initials: P
authors.lastname: Aaby
authors.forename: Adam
authors.initials: A
authors.lastname: Roth
mesh_terms: D017668:Age of Onset; D001500:BCG Vaccine / Q000008:administration & dosage*; D015331:Cohort Studies; D003718:Denmark / Q000453:epidemiology; D005260:Female; D006801:Humans; D007938:Leukemia / Q000453:epidemiology* / Q000209:etiology; D008223:Lymphoma / Q000453:epidemiology* / Q000209:etiology; D008297:Male; D016016:Proportional Hazards Models; D012307:Risk Factors; D012900:Smallpox Vaccine / Q000008:administration & dosage*; D014611:Vaccination / Q000009:adverse effects*
chemical_list: D001500:BCG Vaccine; D012900:Smallpox Vaccine