Study designs for evaluating different efficacy and effectiveness aspects of vaccines

Area of Science:

• Epidemiology
• Biostatistics
• Public Health

Background:

• Vaccine efficacy and effectiveness (VE) are typically quantified as 1 minus the relative risk (RR) observed in vaccinated versus unvaccinated individuals.
• Evaluating vaccination requires careful consideration of the specific research question and the appropriate comparison population and parameter.

Purpose of the Study:

• To present a framework for designing studies evaluating vaccination.
• To link specific scientific questions to appropriate study designs, comparison groups, and effect parameters.

Main Methods:

• The study proposes a framework that connects the scientific question of interest to key study design elements.
• These elements include the choice of comparison groups, the unit of observation, data availability, and the parameter of effect.

Main Results:

• The framework addresses various research interests, including the direct biologic effects of vaccines on susceptibility, infectiousness, and disease progression.
• It also considers indirect effects, total effects, and the broader public health impact of vaccination programs.
• The framework acknowledges the potential influence of behavioral changes on VE estimates.

Conclusions:

• The choice of study design, comparison group, and parameter is critical for accurately assessing vaccine effects.
• This framework provides a structured approach to ensure that study designs align with the intended research questions and objectives.