PubMed · 11907312
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Kevin O'Brien, Jean Wright. 2002. How to write a protocol.. https://doi.org/10.1093/ortho%2F29.1.58
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The widespread use of whole-cell pertussis vaccines in the second half of the 20th century have reduced the incidence of the disease significantly. However, in some countries, concerns about the reactogenicity and potential neurological damage associated with whole-cell vaccines led to a decrease in vaccine acceptance and an increase in morbidity and mortality of pertussis in several countries. This prompted the development of less reactogenic acellular pertussis vaccines combined with diphtheria and tetanus toxoids, initially in Japan and later in other countries. In Europe, the improved diphtheria, tetanus and acellular pertussis (DTPa) vaccine was first introduced in March 1994. The pertussis component of this DTPa vaccine, developed by Glaxo SmithKline, consists of pertussis toxoid, filamentous haemagglutinin and pertactin. The vaccine is well tolerated, with a lower incidence of adverse reactions than after administration of whole-cell vaccines. The long-lasting efficacy and effectiveness of DTPa vaccines have been extensively documented and these are now the cornerstone of a large range of combined vaccines including DTPa-hepatitis B (HBV), DTPa-inactivated polio (IPV) and DTPa-HBV-IPV. A lyophilised Haemophilus influenzae type b (Hib) vaccine can be reconstituted with all of these liquid combinations. The introduction of well-tolerated and efficacious DTPa vaccines and their more polyvalent combinations has improved the acceptance and simplified the implementation of childhood immunisation. This paper is a review of the technical and scientific difficulties encountered and the lessons learned over the 10-year period that it took to develop and introduce six multivalent vaccines using the Glaxo SmithKline DTPa as a building block.
Complex patterns of multiple substance use pose clinical and methodological challenges for substance abuse clinical trials research. To increase measurement precision and internal validity, the modal approach has been to target both treatment interventions and outcome assessment to a single class of abused substance. This strategy warrants reconsideration because it entails limitations in recruitment feasibility and generalization of study findings. This report reviews pros and cons of single versus multiple targeted drugs, suggests guidelines for choosing between these strategies and outlines methods for broadening the scope of substance abuse clinical trails to take abuse of multiple substances into account. We recommend that investigators consider moving away from a single drug focus in three ways. First, include systematic assessment of a wide range of psychoactive substance use throughout the trial and evaluate the impact of study treatments on use of all classes of drugs. Second, except where contraindicated, include patients who use and abuse multiple classes of substances even in trials evaluating treatment of a single targeted drug. Third, consider inclusion of polysubstance abusers or those who primarily abuse multiple classes of substances in the same clinical trial. Although many treatment efficacy questions can best be answered by single focus studies, we recommend that such designs be adopted only after less restrictive designs are first considered.
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