Module 9 2021

23/03/2021

Specific Considerations for Vaccines Clinical Efficacy

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New vaccine : Efficacy

But…efficacy studies are not always possible ● Need to conduct randomised controlled studies

● Studies using placebo or negative controls may be unethical if there is a vaccine that protects against same disease that is recommended in that target population ● Issue when developing second generation vaccines and/or new vaccine combinations (DTaP-HBV-IPV-Hib-MenC; MMRV…) Sample size depends on ● the incidence of the evaluated endpoint ● the expected efficacy ● and the power of the trial As a consequence, vaccine trials are… – Often large and expensive trials – Incidence may vary over time/from one region to another/ … – Study may be not feasible if incidence is low (e.g. meningococcus C, B) HPV: 20,000 Pneumococcal conjugate: 38,000 Rotavirus trials:

> 60,000 (to rule out risk of intussuception)

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