Borrow et al vaccinated 107 children with PCV7 after invasive pneumococcal disease (IPD) following a routine infant immunization schedule. Pneumococcal serotype specific antibody measurements were performed and showed failure to respond to the infecting serotype in 8 children, even though these children received 2 or more doses of PCV. Two children failed to respond to a serotype different than the infecting serotype.(5)