Fig 2. Correlations between immune response to B. anthracis antigens and individual’s age and the number of vaccine doses.

Panel A shows the correlation between age and antibody response to EF, in participants of a study which included individuals who had suffered from cutaneous anthrax previously, been vaccinated with either AVA, LAAV or AVP, or have no history of exposure to anthrax antigens. Antibody responses were measured by ELISA estimating antigen specific antibody in μg / ml. Panels B-D show the correlation between the numbers of doses of vaccine received and antibody response. Antibody responses were measured by ELISA estimating antigen specific antibody against PA (panel B), LF (panel C) and toxin neutralisation activity (Panel D). Partial correlation analyses indicated a significant negative correlation between the parameters (marked on the graphs).