Fig. 2

Antibody response to primary immunization based on sex and age. A Results of the neutralization proxy blocking assay after primary immunization at week 3 with individuals stratified by sex (male, female) or age (18–49 years old, ≥ 50 years old). Each point represents an individual 3 weeks after the first dose of vaccine (week 3). Bars represent the group median. Statistical tests for significant differences between groups were unpaired, two-tailed Wilcoxon-Mann-Whitney test with a significant threshold of P < 0.05