Table 2.

Anti-Circumsporozoite Antibody Titers Pre- and Post-Vaccination in Each Year in Children Who Received RTS,S/AS01_E

Time of Sample Collection	N	Geometric Mean Titer, EU/mL (95% CI)	Geometric Mean Ratio Post- Vaccination–Pre-Vaccination (95% CI)	P Value	N With 2-Fold Increase in Titer (%)	N With 10-Fold Increase in Titer (%)
Both countries
Pre-2017	201	0.95	[Ref]
Post-2017	198	368.9 (317.7–428.4)	446.5 (362.1–550.5)	<.001	194/197 (98)	194/197 (98)
Pre-2018	279	42.4 (37.1–48.5)	[Ref]
Post-2018	279	257.5 (234.5–282.8)	5.81 (4.93–6.86)	<.001	247/279 (89)	76/279 (27)
Pre-2019	291	44.4 (39.2–50.1)	[Ref]
Post-2019	291	177.4 (161.4–195.0)	3.87 (3.40–4.41)	<.001	246/291 (85)	31/291 (11)
Burkina Faso
Pre-2017	87	0.95	[Ref]
Post-2017	83	349.7 (264.1–463.0)	464.9 (314.6–686.8)	<.001	81/83 (98)	81/83 (98)
Pre-2018	132	46.5 (38.6–56.0)	[Ref]
Post-2018	132	256.3 (224.5–292.5)	5.40 (4.18–6.96)	<.001	111/132 (84)	31/132(23)
Pre-2019	135	43.6 (36.9–51.6)	[Ref]
Post-2019	135	200.1 (175.6–228.0)	4.64 (3.88–5.55)	<.001	119/135 (88)	21/135 (16)
Mali
Pre-2017	114	0.95	[Ref]
Post-2017	115	383.5 (326.0–451.1)	433.6 (344.5–545.6)	<.001	113/114 (99)	113/114 (99)
Pre-2018	147	39.0 (32.1–47.4)	[Ref]
Post-2018	147	258.6 (226.3–295.6)	6.20 (4.98–7.71)	<.001	136/147 (93)	45/147 (31)
Pre-2019	156	45.0 (37.7–53.8)	[Ref]
Post-2019	156	159.9 (139.7–183.0)	3.31 (2.75–3.98)	<.001	127/156 (81)	10/156 (6)

Results from all children vaccinated with RTS,S/AS01_E (ie, RTS,S/AS01_E alone and combined groups pooled). At the pre-vaccination contact in 2017, 1 sample from Mali did not provide a conclusive result in the enzyme-linked immunosorbent assay assay. At the post-vaccination contact in 2017, 4 samples from Burkina Faso did not provide a conclusive result. There were no inconclusive results in subsequent years.

Abbreviations: CI, confidence interval; EU, enzyme-linked immunosorbent assay unit.