Module 9 2021

23/03/2021

New vaccine : Immune Correlates and Efficacy

Immunological correlates of protection ● Definition - a laboratory parameter that has been shown to be associated with protection from clinical disease – Can be used to evaluate the efficacy of a vaccine when a correlate of protection has been established – e.g. anti-HBS ≥ 10 mIU/ml = accepted correlate of protection for hepatitis B However, correlates are unknown for most of the diseases for which prophylactic vaccines are needed ● For example - malaria, tuberculosis, CMV, RSV, HIV, HCV, etc…).

For these new vaccines, efficacy data are theoretically requested for licensure

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Efficacy vs Effectiveness

When pre-licensure efficacy trials are not feasible or not ethical

Regulatory authorities accept to grant the license based on immunogenicity data

But generally require post-licensure effectiveness studies = “real-life efficacy” (less restrictive entry criteria) ● Comparison of a vaccinated population vs a non-vaccinated population – Vaccinated communities vs unvaccinated communities (e.g. community randomized trial) – Cases in vaccinated subjects vs cases in matched controls (case control study) ● Historical control : observe decrease in the incidence of the disease after introduction of a given vaccine in the UMV programme

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