Preventing pneumococcal disease among infants and young children. Recommendations of the Advisory Committee on Immunization Practices (ACIP).
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In February 2000, a 7-valent pneumococcal polysaccharide-protein conjugate vaccine (Prevnar, marketed by Wyeth Lederle Vaccines) was licensed for use among infants and young children. CDC's Advisory Committee on Immunization Practices (ACIP) recommends that the vaccine be used for all children aged 2-23 months and for children aged 24-59 months who are at increased risk for pneumococcal disease (e.g., children with sickle cell disease, human immunodeficiency virus infection, and other immunocompromising or chronic medical conditions). ACIP also recommends that the vaccine be considered for all other children aged 24-59 months, with priority given to a) children aged 24-35 months, b) children who are of Alaska Native, American Indian, and African-American descent, and c) children who attend group day care centers. This report includes ACIP's recommended vaccination schedule for infants at ages 2, 4, 6, and 12-15 months. This report also includes a pneumococcal vaccination schedule for infants and young children who are beginning their vaccination series at an older age and for those who missed doses. In addition, this report updates earlier recommendations for use of 23-valent pneumococcal polysaccharide vaccine among children aged > or =2 years. Among children aged 24-59 months for whom polysaccharide vaccine is already recommended, ACIP recommends vaccination with the new conjugate vaccine followed, > or =2 months later, by 23-valent polysaccharide vaccine. Conjugate vaccine has not been studied sufficiently among older children or adults to make recommendations for its use among persons aged > or =5 years. Persons aged > or =5 years who are at increased risk for serious pneumococcal disease should continue to receive 23-valent polysaccharide vaccine in accordance with previous ACIP recommendations. (+info)
Ability of 3 different meningococcal C conjugate vaccines to induce immunologic memory after a single dose in UK toddlers.
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To test for immunologic memory after a single dose of meningococcal C conjugate (MCC) vaccine in toddlers, 226 children 12-18 months old were randomized to receive 1 of 3 MCC vaccines, with a C polysaccharide booster 6 months later. The protein conjugate was diphtheria mutant toxoid in 2 vaccines (MCC-CRM(197)) and was tetanus toxoid in the third (MCC-TT). One month after the MCC vaccines, 91%-100% of children had serum bactericidal antibody (SBA) titers > or =8, and 89%-100% had a > or =4-fold increase. Geometric mean titer (GMT) increased from <4 to 215 (95% confidence interval [CI], 166-279). MCC-TT induced higher SBA GMTs (P<.001) and higher proportions with SBA > or =8 (P=.02) than did the MCC-CRM(197) vaccines. By 6 months, GMTs had decreased to 55.1 (95% CI, 40-76), but IgG antibody avidity increased (P<.001). Induction of immunologic memory was confirmed by a GMT of 1977 (range, 1535-2547) after the polysaccharide booster and a further increase in avidity. This evidence justified the use of a single dose in a catch-up immunization program for children 1-18 years old. (+info)
Immunologic memory 5 years after meningococcal A/C conjugate vaccination in infancy.
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Infant vaccination with meningococcal conjugates may provide long-term protection against disease. Antibody levels and immunologic memory were assessed in 5-year-old Gambian children who received meningococcal A/C conjugate vaccination (MenA/C) in infancy. At 2 years, they were randomized to receive a booster of MenA/C (conjugate group), meningococcal A/C polysaccharide (MPS group), or inactivated polio vaccine (IPV group). All groups were revaccinated with 10 microg MPS at 5 years of age, as were 39 previously unvaccinated age-matched control subjects. Before revaccination, titers were higher in the conjugate and MPS groups than in control subjects (P<.001); titers for the IPV group were similar to those for control subjects. Ten days after revaccination, the conjugate and IPV groups had similar serogroup C serum bactericidal antibody titers (3421 vs. 2790, respectively). These levels were significantly higher than those in the MPS (426) and control (485) groups (P<.001). Thus, immunologic memory was sustained for > or =5 years; however, MPS challenge at 2 years interfered with a subsequent memory response. (+info)
Potency of a genetically detoxified mucosal adjuvant derived from the heat-labile enterotoxin of Escherichia coli (LTK63) is not adversely affected by the presence of preexisting immunity to the adjuvant.
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The objective of the current studies was to evaluate whether the potency of a genetically detoxified mucosal adjuvant, derived from heat-labile enterotoxin of Escherichia coli (LTK63), was adversely affected by preexisting immunity. Studies of mice and pigs have involved consecutive intranasal immunization with LTK63 and 2 different vaccines (influenza virus hemagglutinin and a protein-polysaccharide conjugate of Neisseria meningitidis group C). The antibody responses to the vaccines plus LTK63 in naive animals were compared with the responses achieved in animals that previously had been immunized with the alternate vaccine plus LTK63. The data showed that the responses of both animal models to intranasal immunization were not adversely affected by the presence of preexisting immunity to the LTK63 adjuvant. (+info)
Choosing a route of administration for quadrivalent meningococcal polysaccharide vaccine: intramuscular versus subcutaneous.
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A clinical trial was conducted to compare intramuscular (im) with subcutaneous (sc) routes for administration of quadrivalent meningococcal polysaccharide vaccine in 141 adults. Safety assessment showed the im route had reduced erythema (P<.01) and reduced headache on days 1 and 2 (P<.05). Serological testing for serum bactericidal antibody titers against capsular groups A and C did not detect significant differences. (+info)
Efficacy of a pneumococcal conjugate vaccine against acute otitis media.
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BACKGROUND: Ear infections are a common cause of illness during the first two years of life. New conjugate vaccines may be able to prevent a substantial portion of cases of acute otitis media caused by Streptococcus pneumoniae. METHODS: We enrolled 1662 infants in a randomized, double-blind efficacy trial of a heptavalent pneumococcal polysaccharide conjugate vaccine in which the carrier protein is the nontoxic diphtheria-toxin analogue CRM197. The children received either the study vaccine or a hepatitis B vaccine as a control at 2, 4, 6, and 12 months of age. The clinical diagnosis of acute otitis media was based on predefined criteria, and the bacteriologic diagnosis was based on a culture of middle-ear fluid obtained by myringotomy. RESULTS: Of the children who were enrolled, 95.1 percent completed the trial. With the pneumococcal vaccine, there were more local reactions than with the hepatitis B vaccine but fewer than with the combined whole-cell diphtheria-tetanus-pertussis and Haemophilus influenzae type b vaccine that was administered simultaneously. There were 2596 episodes of acute otitis media during the follow-up period between 6.5 and 24 months of age. The vaccine reduced the number of episodes of acute otitis media from any cause by 6 percent (95 percent confidence interval, -4 to 16 percent [the negative number indicates a possible increase in the number of episodes]), culture-confirmed pneumococcal episodes by 34 percent (95 percent confidence interval, 21 to 45 percent), and the number of episodes due to the serotypes contained in the vaccine by 57 percent (95 percent confidence interval, 44 to 67 percent). The number of episodes attributed to serotypes that are cross-reactive with those in the vaccine was reduced by 51 percent, whereas the number of episodes due to all other serotypes increased by 33 percent. CONCLUSIONS: The heptavalent pneumococcal polysaccharide-CRM197 conjugate vaccine is safe and efficacious in the prevention of acute otitis media caused by the serotypes included in the vaccine. (+info)
Recombinant Neisseria meningitidis transferrin binding protein A protects against experimental meningococcal infection.
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To better characterize the vaccine potential of Neisseria meningitidis transferrin binding proteins (Tbps), we have overexpressed TbpA and TbpB from Neisseria meningitidis isolate K454 in Escherichia coli. The ability to bind human transferrin was retained by both recombinant proteins, enabling purification by affinity chromotography. The recombinant Tbps were evaluated individually and in combination in a mouse intraperitoneal-infection model to determine their ability to protect against meningococcal infection and to induce cross-reactive and bactericidal antibodies. For the first time, TbpA was found to afford protection against meningococcal challenge when administered as the sole immunogen. In contrast to the protection conferred by TbpB, this protection extended to a serogroup C isolate and strain B16B6, a serogroup B isolate with a lower-molecular-weight TbpB than that from strain K454. However, serum from a TbpB-immunized rabbit was found to be significantly more bactericidal than that from a TbpA-immunized animal. Our evidence demonstrates that TbpA used as a vaccine antigen may provide protection against a wider range of meningococcal strains than does TbpB alone. This protection appears not to be due to complement-mediated lysis and indicates that serum bactericidal activity may not always be the most appropriate predictor of efficacy for protein-based meningococcal vaccines. (+info)
Serological basis for use of meningococcal serogroup C conjugate vaccines in the United Kingdom: reevaluation of correlates of protection.
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The antibody data supporting the use of meningococcal serogroup C conjugate (MCC) vaccines in the United Kingdom were generated by serum bactericidal assay (SBA) using rabbit complement (rSBA). This may give higher titers than those obtained with human complement (hSBA), for which the "gold standard" correlate of protection for meningococcal C disease is a titer of > or =4. Comparison of rSBA and hSBA titers in sera from unvaccinated adults with an rSBA titer of > or =8 showed that for 93% (27 of 29) the titer was > or =4 by hSBA, confirming natural protection. Furthermore, sera from MCC vaccinees showed that an rSBA titer of <8 or > or =128 discriminated susceptibility and protection well (85% with rSBA titers of <8 had hSBA titers of <4, and 99% with rSBA titers of > or =128 had hSBA titers of > or =4). However, discrimination was poor in the rSBA titer range 8 to 64, with only 60% having hSBA titers of > or =4. In such cases we propose that protection can be assumed if there is a fourfold rise in titer between pre- and postvaccination sera or if there is a characteristic booster response to a polysaccharide challenge dose with, if available, evidence of antibody avidity maturation or an hSBA titer of result > or =4. Applying these criteria to toddlers, 10 to 40% of whom had titers in the range 8 to 64 after a single dose of MCC vaccine, showed that 94% had a fourfold rise in titer, including 98% of those in the titer range 8 to 64. In addition, of those with titers of <128 post-MCC vaccination, 90% had titers of > or =128 after a 10-microg polysaccharide booster dose, compared with only 7% of unprimed age-matched toddlers given a full 50-microg dose. Furthermore, the increase in geometric mean avidity index pre- and postbooster was independent of post-primary MCC titer. These results indicated that the majority of toddlers with an rSBA titer between 8 and 64, and some of those with an hSBA result of <4, have mounted a protective immune response with the induction of immunological memory. (+info)