Haemophilus influenzae Type b Vaccine Failure in Portugal: A Nationwide Multicenter Pediatric Survey.

In Portugal, more than 95% of children are vaccinated against Hib, but severe Hib-ID cases still occur. No predisposing factors were clearly identified to justify the increased number of VF in recent years. Along with continued Hi-ID surveillance, Hib colonization and serologic studies should be implemented.