Serologic responses to ACYW135 polysaccharide meningococcal vaccine in Saudi children under 5 years of age.
An immunization campaign with meningococcal ACYW135 polysaccharide vaccine was conducted in 2003 by the Saudi Arabian Ministry of Health and included a study to evaluate the immune responses in children under 5 years of age in the Al Qassim region of Saudi Arabia. Children who were >/=24 months old were given one dose of tetravalent polysaccharide vaccine, while younger children were given two doses with an interval of 2 to 3 months. Blood samples were collected prevaccination and 1 month after the second dose for children younger than 24 months old and 1 month after the single dose for older children. Serogroup-specific antibody responses were determined by serum bactericidal antibody (SBA) assays and a tetraplex immunoglobulin G (IgG) bead assay. Significant increases in the proportions of individuals who were >/=24 months old with SBA titers of >/=8 were observed pre- to postvaccination for all serogroups. Age-dependent increases in the percentage of individuals with SBA titers of >/=8 1 month postvaccination were observed for each serogroup. Age-dependent increases in postvaccination IgG levels were observed for serogroup A (menA), serogroup W135 (menW), and serogroup Y (menY) but not for serogroup C (menC). Two doses of tetravalent polysaccharide vaccine in individuals who were </=18 months old were poorly immunogenic for menC, menW, and menY. However, for menA, 42% of the children who were 18 months old were putatively protected with SBA titers of >/=8. A high percentage of subjects who were >/=2 years of age were putatively protected for menA; a similar level was observed for menY for children who were 4 years of age but not for younger children. However, for menC and menW poor levels of putative protection were still evident at 4 years of age.
Al-Mazrou
Y
Y
Meningococcal Reference Unit, HPA North West Laboratory, Manchester Royal Infirmary, Manchester, United Kingdom.
Khalil
M
M
Borrow
R
R
Balmer
P
P
Bramwell
J
J
Lal
G
G
Andrews
N
N
Al-Jeffri
M
M
D000907:Antibodies, Bacterial / Q000097:blood*; D001770:Blood Bactericidal Activity; D002675:Child, Preschool; D006801:Humans; D007074:Immunoglobulin G / Q000097:blood; D007223:Infant; D008589:Meningococcal Infections / Q000517:prevention & control; D022401:Meningococcal Vaccines / Q000008:administration & dosage / Q000276:immunology*; D009345:Neisseria meningitidis / Q000145:classification* / Q000276:immunology*; D011135:Polysaccharides, Bacterial / Q000008:administration & dosage / Q000276:immunology*; D012529:Saudi Arabia; D012703:Serotyping; D014611:Vaccination; D018074:Vaccines, Conjugate / Q000008:administration & dosage / Q000276:immunology
D000907:Antibodies, Bacterial; D007074:Immunoglobulin G; D022401:Meningococcal Vaccines; D011135:Polysaccharides, Bacterial; D018074:Vaccines, Conjugate