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     MONOVALENT TO QUADRIVALENT VACCINES: BROADENING PROTECTION AGAINST
                          MENINGOCOCCAL DISEASE
                           1            2           3             4           5       6
                M.-K. Taha , J. Schmitt , J. Findlow , P. De Wals , R. Baxter , P. Dull
1                                                                                 2
 Invasive Bacterial Infections Provisional Unit, Institut Pasteur, Paris, France, Novartis Vaccines and
                                              3
    Diagnostics GmbH, Marburg, Germany, Vaccine Evaluation Unit, Health Protection Agency,
                  4                                                 5
 Manchester, UK, Laval University, Quebec City, QC, Canada, KP Vaccine Study Center, Oakland,
                      6
                CA, Novartis Vaccines and Diagnostics, Inc., Cambridge, MA, USA
In many countries, large catch-up campaigns using meningococcal serogroup C conjugate (MenC)
vaccines have led to a dramatic decrease in serogroup C disease. It is also believed that a herd
immunity effect has contributed to the effectiveness of these vaccines. However, while vaccine
effectiveness is high, waning of the protective titer in the youngest population has been of concern.
Alternative vaccination schedules and vaccination strategies that offer sustained protection have been
considered, eg, a booster dose in adolescents (recently recommended in Austria, Canada, and
Switzerland). The rationale for this booster is to ensure that adolescents are adequately protected as
they enter a period of increased risk, primarily due to changing behaviors and increased exposure to
risk factors, such as close-quarters living, and secondly, to maintain the potential herd effect, by
reducing carriage.

Meningococcal ACWY (MenACWY) conjugate vaccines have been developed that offer the possibility
of broadening protection. An investigational MenACWY vaccine with CRM 197 carrier protein
(MenACWY-CRM) has been shown to be highly immunogenic in adolescents and adults. In short-
term immunogenicity and safety head-to-head trials, more individuals achieved a protective immune
response with MenACWY-CRM than licensed comparators, such as MenACWY-D and
polysaccharide vaccines. Although these MenACWY vaccines contribute to protection against four of
the five disease-causing serogroups, development of a serogroup B vaccine using the same
technology has not been possible. An investigational recombinant serogroup B vaccine, containing
multiple antigens, is now in Phase III development following reverse vaccinology findings. Results
from clinical studies have demonstrated that the vaccine is immunogenic with acceptable tolerability in
infants and adults.

				
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