Abstract
This double-blind, randomized study evaluated the immunogenicity and safety of three production lots of the fully liquid combination DTwP-Hep-Hib vaccine, Quinvaxem (®) (Crucell, The Netherlands) in 360 healthy infants aged 42-64 d old given at 6, 10 and 14 weeks of age (Core Study). The Core Study was followed by an open-label Booster Phase evaluating immunogenicity and safety of a booster dose of Quinvaxem (®) given with either concomitant or deferred measles vaccine in 227 infants who completed the Core Study. One month after the third dose of Quinvaxem (®) immune responses reflecting seroprotection or seroconversion were observed in more than 90% of infants for all three vaccine lots. Quinvaxem (®) elicited a strong booster response as demonstrated by a large increase in antibodies against all antigens, which appeared to be unaffected by concomitant administration of the measles vaccine. Safety results were in line with previous reports for Quinvaxem (®) with no unexpected adverse events (AEs) being reported. In the Core Study and Booster Phase, Quinvaxem (®) was well tolerated. No study vaccine-related serious AEs were reported. Thus, Quinvaxem (®) was immunogenic and well-tolerated when administered to infants according to a 6-10-14 week vaccination schedule. The three production lots had consistent reactogenicity and immunogenicity profiles. The booster dose of Quinvaxem (®) was also immunogenic and safe, regardless of whether a monovalent measles vaccine was administered concomitantly or one month later.