Vac­cine De­vel­op­ment Phases

BioSpectrum (India) - - COVER STORY -

Pre-Clin­i­cal Tri­als

In vac­cine de­vel­op­ment, the first step to iden­ti­fy­ing a vac­cine can­di­date is the pre-clin­i­cal de­vel­op­ment stage. Dur­ing this stage, the re­searchers care­fully select the anti­gen and ap­pro­pri­ate tech­nolo­gies, and then both in vitro and in vivo tests are per­formed. The in­for­ma­tion col­lected from these stud­ies is vi­tal to be­gin safe clin­i­cal tri­als.

Phase I clin­i­cal tri­als

Phase I tri­als in­volve a small num­ber of healthy vol­un­teers (around 20-50). The re­searchers test the can­di­date vac­cine for the first time in hu­mans in or­der to eval­u­ate its safety, de­ter­mine a safe dosage range, and iden­tify vac­cine-re­lated side ef­fects. This is achieved by com­par­ing the vac­cine with a con­trol or an in­ac­tive sub­stance called placebo (e.g. sa­line so­lu­tion). Phase I tri­als can also pro­vide ini­tial data on the dose and the time needed be­tween vac­ci­na­tions that will lead to an op­ti­mal im­mune re­sponse. This first phase of the clin­i­cal tri­als lasts 12 to 18 months.

Phase II clin­i­cal tri­als

If the can­di­date vac­cine presents op­ti­mal re­sults in phase I, it will then un­dergo Phase II tri­als dur­ing which the can­di­date vac­cine is ad­min­is­tered to a larger group of peo­ple (around 100-300) to fur­ther eval­u­ate its safety and im­muno­genic­ity. This phase ex­plores more deeply the right dose and ad­min­is­tra­tion sched­ule and can last 2 or more years.

Phase III clin­i­cal tri­als

The most promis­ing vac­cine can­di­dates move into Phase III en­rolling 3,000 to 50,000 sub­jects. The goal of this phase is to con­duct a large-scale safety and ef­fi­cacy study in the rel­e­vant pa­tient pop­u­la­tion at which the vac­cine is aimed. More­over dur­ing this phase con­comi­tant ad­min­is­tra­tion with other vac­cines is tested. Phase III clin­i­cal tri­als can last 3 to 5 years. Phase IV or Phar­ma­covig­i­lance

Once a vac­cine has been mar­keted, phar­ma­covig­i­lance ac­tiv­i­ties take place in or­der to carry on a strict safety su­per­vi­sion of the vac­cines and de­tect, as­sess, un­der­stand, pre­vent and com­mu­ni­cate any ad­verse events fol­low­ing im­mu­ni­sa­tion, or of any other vac­cine- or im­mu­ni­sa­tion-re­lated is­sues. Long-term fol­low-up tri­als are of­ten con­ducted to pro­vide ev­i­dence that the pro­tec­tion of­fered by the vac­cine is long-last­ing.

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