Serious neurological conditions following pertussis immunization: an analysis of endotoxin levels, the vaccine adverse events reporting system (VAERS) database and literature review.

Abstract

The purpose of this study was to determine the potential risks for the development and outcome of serious neurological illnesses following whole-cell DTP vaccination and also to determine if the switch to using acellular DTaP vaccine in the US has had any effect on the incidence rate of serious neurological illnesses following vaccination. This study used the Limulus amebocyte lysate (LAL) endotoxin assay to determine the levels of endotoxin in various commercially available whole-cell and acellular DTaP vaccines, analysed the Vaccine Adverse Events Reporting System (VAERS) database to determine the clinical effects of the use of whole-cell DTP and acellular DTaP vaccines in the US and reviewed recently published pertinent studies that analysed the incidence rates of serious neurological illness following whole-cell DTP and acellular DTaP vaccines. The results indicated that whole-cell DTP vaccine contained high levels of endotoxin and was statistically significantly more reactogenic than acellular DTaP vaccine. The presence of bias in the VAERS database was not borne-out. The recommendation by the American Academy of Paediatrics to use acellular DTaP vaccine for the entire childhood vaccination schedule beginning in 1996 and the absence of the availability of whole-cell DTP in the US beginning in 2001 seems well justified based upon the results of this study.