Evaluating the safety and immunogenicity of yellow fever vaccines: a systematic review

Abstract

Purpose: To review the safety and immunogenicity of yellow fever vaccines. Literature search: The Cochrane Library (including the Cochrane CENTRAL Register of Controlled Trials, the Cochrane Database of Systematic Reviews, and the NHS Database of Abstracts of Reviews of Effects); MEDLINE; EMBASE; BIOSIS Previews; Global Health; CAB Abstracts; and the Lilacs Database of Latin American and Caribbean literature were searched for individual studies and systematic reviews through January 1, 2015. Results: Six yellow fever vaccines are currently produced, and they are effective against all seven yellow fever virus strains. There is a 99.2% homology of the genome sequences of the six current vaccines. Four systematic reviews identified very small numbers of serious adverse events. A systematic review (updated) of all published cases identified 133 serious adverse events that met the Brighton Collaboration criteria: 32 anaphylactic, 42 neurologic (one death), 57 viscerotropic (25 deaths), and two of both neurologic and viscerotropic SAEs. The Sanofi Pasteur Global Pharmacovigilance database reported 276 million doses of Stamaril™ distributed worldwide and identified 12 reports of yellow fever vaccine-associated viscerotropic disease (YEL-AVD), 24 of yellow fever vaccine-associated neurologic disease (YEL-AND), and 33 reports of anaphylaxis (many already published). The Biomanguinhos manufacturer's database reported 110 million doses distributed worldwide between 1999 and 2009, and the rate of YEL-AND was estimated at 0.084/100,000 doses distributed and YEL-AVD at 0.02/100,000 doses distributed. Conclusion: Reports of serious adverse events are mostly from travelers from developed countries, and there is likely serious underreporting for developing countries. On the basis of the published reports, the yellow fever vaccines are very safe and probably provide life-long immunity.