Baseline characteristics of physicians immunised and non-immunised against bias for the disease encountered in the biasing phase
| Immunised | Non-immunised | Overall | |
| Age (years) | |||
| Mean (95% CI) | 27.39 (26.52 to 28.26) | 27.91 (27.18 to 28.64) | 27.67 (27.11 to 28.22) |
| Sex | |||
| Male | 23 (52%) | 21 (45%) | 44 (48%) |
| Female | 21 (48%) | 26 (55%) | 47 (52%) |
| Experience with the diseases of the study (range 0–5) | |||
| Mean (95% CI) | 2.77 (2.65 to 2.90) | 2.66 (2.48 to 2.85) | 2.72 (2.61 to 2.83) |