Challenge Study • Small cohorts (40-60) • Controlled environment • High attack rate • Known inoculation date • Short duration (< 6 months)
Development Benefits • Smaller sample size requirements to obtain statistically meaningful data • Facilitates the development of prophylactic and therapeutic small / large molecule drugs and vaccines, as well as providing early safety data in healthy volunteers • Predictions of effectiveness in later field studies (de-risking) • Collection of data in controlled environments • Reduced need for extensive Ph2a trials, shortening timelines and associated costs as well as avoiding the necessity for high prevalence seasons for infectious diseases
• Go / No-Go decisions • May predict field trial • Design / performance Phase II Field Study • Large cohorts (250-300) • Uncontrolled environment • Low attack rate (prevalence) • Unknown inoculation date • Long duration (>1yr) • High cost • Restricted window for enrolment • Extensive data analysis required for decisions • Noise / data ratio
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