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Table 2 Cox regression survival analysisa of time to clinical malaria episodeb between days 90 and 240

From: Immunoglobulin G subclass and antibody avidity responses in Malian children immunized with Plasmodium falciparum apical membrane antigen 1 vaccine candidate FMP2.1/AS02A

Predictor variable AMA1 vaccine group Control group
No primary outcome episodes before day 90 (n = 66) No parasitaemia before day 90 (n = 49) No primary outcome episodes before day 90 (n = 22)
Hazard ratioc P Hazard ratio P Hazard ratio P
log10 (IgG1 day 0) 1.15 [0.85, 1.55] 0.36 1.38 [0.88, 2.16] 0.16 1.17 [0.64, 2.14] 0.60
log10 (IgG2 day 0) 1.07 [0.65, 1.77] 0.80 0.92 [0.30, 2.79] 0.88 0.99 [0.29, 3.34] 0.98
log10 (IgG3 day 0) 1.27 [0.59, 2.74] 0.54 1.45 [0.55, 3.84] 0.45 0.77 [0.24, 2.48] 0.66
log10 (IgG4 day 0) 1.36 [0.82, 2.27] 0.24 1.59 [0.47, 5.46] 0.46 5.70 [0.58, 56.3] 0.14
log10 (cytophilic ratiod day 0) 1.42 [0.80, 2.54] 0.23 1.93 [0.92, 4.02] 0.081 1.30 [0.50, 3.39] 0.60
log10 (IgG1 day 90) 1.07 [0.42, 2.77] 0.88 0.785 [0.21, 2.89] 0.72 1.20 [0.66, 2.18] 0.55
log10 (IgG2 day 90) 0.85 [0.46, 1.59] 0.62 0.73 [0.28, 1.90] 0.52 1.35 [0.43, 4.27] 0.61
log10 (IgG3 day 90) 1.81 [0.93, 3.51] 0.079 1.62 [0.73, 3.56] 0.23 0.94 [0.36, 2.43] 0.90
log10 (IgG4 day 90) 1.05 [0.67, 1.65] 0.84 0.91 [0.48, 1.73] 0.77 3.58 [0.16, 79.9] 0.42
log10 (cytophilic ratio day 90) 0.83 [0.40, 1.75] 0.63 1.06 [0.29,3.81] 0.93 1.21 [0.48, 3.09] 0.68
  1. aUsing Firth’s penalized likelihood
  2. bClinical malaria episode using the primary outcome definition, i.e., an episode of malaria with axillary temperature of ≥ 37.5 °C and asexual P. falciparum density of ≥ 2500 parasites/mm3 of blood
  3. cHazard ratio and 95% confidence intervals for risk of clinical malaria episode after day 90
  4. dCytophilic ratio is the sum of IgG1 and IgG2 titers divided by the sum of the IgG3 and IgG4 titers