An evaluation of the indirect cohort method to estimate the effectiveness of the pneumococcal polysaccharide vaccine

Broome et al. The premise of the method was that the vaccine would be expected to be effective in preventing disease caused by serotypes that are contained in the vaccine, but to have no effect on the risk of disease due to other pneumococcal serotype (excluding serologically related serotypes). Under Broome's method, individuals diagnosed with invasive pneumococcal disease (IPD), that is where Streptococcus pneumoniae was isolated from a normally