Table 1.

Comparison of endpoints of vaccine trials. The mode of action of the vaccine will determine the type of trial and endpoint that is used to evaluate their efficacy.

Target of vaccine*	Trial	Endpoint	Vaccine efficacy	Type of follow up	References
Pre-erythrocytic	Sporozoite challenge (Phase IIa)	Infection	$1 - \frac{N_{V}}{N_{U V}}$	Daily ACD	[30, 31]
		Delayed patency (if vaccinees become infected)	--	Daily ACD	[32–34]
		Number of primary merozoites**	$1 - \frac{{\overset{⌢}{P}}_{V}}{{\overset{⌢}{P}}_{U V}}$	Daily ACD	[5]
	Field trial in endemic setting (Phase IIb/III)	Time to first infection or first episode	1-HR	ACD (for time to infection) ACD or PCD (for first episodes)	[35, 36]
		Incidence of disease episodes	$1 - \frac{I_{V}}{I_{U V}}$	ACD or PCD	For multiple episodes [36]
Blood stage	Field trial in endemic setting	Incidence of disease episodes (first episode or multiple episodes) (Phase IIb/III)	$1 - \frac{I_{V}}{I_{U V}}$	ACD or PCD	[15, 16, 37]
		Density of infection (Phase IIb)	$1 - \frac{{\overset{⌢}{D}}_{V}}{{\overset{⌢}{D}}_{U V}}$	ACD	[9]

N = number of volunteers infected, P = mean number of primary merozoites, HR = Hazards ratio, I=incidence, D = mean density, V = vaccinated, UV = unvaccinated, ACD = active case detection, PCD = passive case detection

* Transmission blocking (mosquito stage) vaccines are not considered in this analysis.

** This endpoint requires PCR and is not currently used as a primary endpoint