By year 10, 77.4% (n = 137) of participants had received vaccination
with a CRM (modified diphtheria toxoid)-conjugated
meningococcal vaccine and 7.9% (n = 14) had received a TTconjugated
meningococcal vaccine since the initial dTpa booster
dose. Most meningococcal vaccines were given 1 month after the
initial dTpa study vaccination (at the time of blood sampling).
The most common reasons for non-participation in this extension
study were: lost to follow-up (n = 92), unwilling to participate
(not due to an AE, n = 88) or ineligible (n = 30). No participant
required a booster dose of dTpa at year 8.5.