Authors: Alfred Spira Pierre Bégué André Aurengo
Publish Date: 2015/02/18
Volume: 62, Issue: 1, Pages: 1-2
Abstract
We would like to comment on the interesting paper by Le Houe’zec concerning a relationship between hepatitis B HB vaccination and a subsequent risk of multiple sclerosis MS recently published in your Journal1 The author states that this link is proven and that it could be causalConsidering the immunization mass campaign which occurred in France between 1994 and 1997 as a “natural experiment” is an excellent idea But to consider “quasi experiment” as an experimental design and to eliminate possible confounders the analysis must rely on very precise data both on population at risk as a whole and on individuals who have been or not been vaccinatedThe paper relies on an ecological analysis derived from two sets of medicoadministrative data bases namely those of the French health insurance system CNAM and of spontaneous postvaccine reports to the French pharmacovigilance agency which both concern the French population as a whole and no data collected on individuals
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