PREVNAR- streptococcus pneumoniae type 4 capsular polysaccharide diphtheria crm197 protein conjugate antigen, streptococcus pneumoniae type 6b capsular polysaccharide diphtheria crm197 protein conjugate antigen, streptococcus pneumoniae type 9v capsular polysaccharide diphtheria crm197 protein conjugate antigen, streptococcus pneumoniae type 14 capsular polysaccharide diphtheria crm197 protein conjugate antigen, streptococcus pneumoniae type 18c capsular polysaccharide diphtheria crm197 protein conjugate antigen, streptococcus pneumoniae type 19f capsular polysaccharide diphtheria crm197 protein conjugate antigen and streptococcus pneumoniae type 23f capsular polysaccharide diphtheria crm197 protein conjugate antigen injection, suspension
Wyeth Pharmaceutical Division of Wyeth Holdings Corporation, a subsidiary of Pfizer Inc.
Pneumococcal 7-valent Conjugate Vaccine (Diphtheria CRM197 Protein), Prevnar® , is a sterile solution of saccharides of the capsular antigens of Streptococcus pneumoniae serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F individually conjugated to diphtheria CRM197 protein. Each serotype is grown in soy peptone broth. The individual polysaccharides are purified through centrifugation, precipitation, ultrafiltration, and column chromatography. The polysaccharides are chemically activated to make saccharides which are directly conjugated to the protein carrier CRM197 to form the glycoconjugate. This is effected by reductive amination. CRM197 is a nontoxic variant of diphtheria toxin isolated from cultures of Corynebacterium diphtheriae strain C7 (β197) grown in a casamino acids and yeast extract-based medium. CRM197 is purified through ultrafiltration, ammonium sulfate precipitation, and ion-exchange chromatography. The individual glycoconjugates are purified by ultrafiltration and column chromatography and are analyzed for saccharide to protein ratios, molecular size, free saccharide, and free protein.
The individual glycoconjugates are compounded to formulate the vaccine, Prevnar®. Potency of the formulated vaccine is determined by quantification of each of the saccharide antigens, and by the saccharide to protein ratios in the individual glycoconjugates.
Prevnar® is manufactured as a liquid preparation. Each 0.5 mL dose is formulated to contain: 2 μg of each saccharide for serotypes 4, 9V, 14, 18C, 19F, and 23F, and 4 μg of serotype 6B per dose (16 μg total saccharide); approximately 20 μg of CRM197 carrier protein; and 0.125 mg of aluminum per 0.5 mL dose as aluminum phosphate adjuvant.
S. pneumoniae is an important cause of morbidity and mortality in persons of all ages worldwide. The organism causes invasive infections, such as bacteremia and meningitis, as well as pneumonia and upper respiratory tract infections including otitis media and sinusitis. In children older than 1 month, S. pneumoniae is the most common cause of invasive disease.1 Data from community-based studies performed between 1986 and 1995, indicate that the overall annual incidence of invasive pneumococcal disease in the United States (US) is an estimated 10 to 30 cases per 100,000 persons, with the highest risk in children aged less than or equal to 2 years of age (140 to 160 cases per 100,000 persons).2,3 Children in group child care have an increased risk for invasive pneumococcal disease.4,5 Immunocompromised individuals with neutropenia, asplenia, sickle cell disease, disorders of complement and humoral immunity, human immunodeficiency virus (HIV) infections or chronic underlying disease are also at increased risk for invasive pneumococcal disease.5 S. pneumoniae is the most common cause of bacterial meningitis in the US.1 The annual incidence of pneumococcal meningitis in children between 1 to 23 months of age is approximately 7 cases per 100,000 persons.1 Pneumococcal meningitis in childhood has been associated with 8% mortality and may result in neurological sequelae (25%) and hearing loss (32%) in survivors.6
Acute otitis media (AOM) is a common childhood disease, with more than 60% of children experiencing an episode by one year of age, and more than 90% of children experiencing an episode by age 5. Prior to the US introduction of Prevnar® in the year 2000, approximately 24.5 million ambulatory care visits and 490,000 procedures for myringotomy with tube placement were attributed to otitis media annually.7,8 The peak incidence of AOM is 6 to 18 months of age.9 Otitis media is less common, but occurs, in older children. In a 1990 surveillance by the Centers for Disease Control and Prevention (CDC), otitis media was the most common principal illness diagnosis in children 2-10 years of age.10 Complications of AOM include persistent middle ear effusion, chronic otitis media, transient hearing loss, or speech delays and, if left untreated, may lead to more serious diseases such as mastoiditis and meningitis. S. pneumoniae is an important cause of AOM. It is the bacterial pathogen most commonly isolated from middle ear fluid, identified in 20% to 40% of middle ear fluid cultures in AOM.11,12 Pneumococcal otitis media is associated with higher rates of fever, and is less likely to resolve spontaneously than AOM due to either nontypeable H. influenzae or M. catarrhalis.13,14 Prior to the introduction of Prevnar® , the seven serotypes contained in the vaccine accounted for approximately 60% of AOM due to S. pneumoniae (12%-24% of all AOM).15
The exact contribution of S. pneumoniae to childhood pneumonia is unknown, as it is often not possible to identify the causative organisms. In studies of children less than 5 years of age with community-acquired pneumonia, where diagnosis was attempted using serological methods, antigen testing, or culture data, 30% of cases were classified as bacterial pneumonia, and 70% of these (21% of total community-acquired pneumonia) were found to be due to S. pneumoniae.16
In the past decade the proportion of S. pneumoniae isolates resistant to antibiotics has been on the rise in the US and worldwide. In a multi-center US surveillance study, the prevalence of penicillin and cephalosporin-nonsusceptible (intermediate or high level resistance) invasive disease isolates from children was 21% (range <5% to 38% among centers), and 9.3% (range 0%-18%), respectively. Over the 3-year surveillance period (1993-1996), there was a 50% increase in penicillin-nonsusceptible S. pneumoniae (PNSP) strains and a three-fold rise in cephalosporin-nonsusceptible strains.5 Although generally less common than PNSP, pneumococci resistant to macrolides and trimethoprim-sulfamethoxazole have also been observed. Day care attendance, a history of ear infection, and a recent history of antibiotic exposure, have also been associated with invasive infections with PNSP in children 2 months to 59 months of age.4,5 There has been no difference in mortality associated with PNSP strains.5,6 However, the American Academy of Pediatrics (AAP) revised the antibiotic treatment guidelines in 1997 in response to the increased prevalence of antibiotic-resistant pneumococci.17
Approximately 90 serotypes of S. pneumoniae have been identified based on antigenic differences in their capsular polysaccharides. The distribution of serotypes responsible for disease differ with age and geographic location.18
Serotypes 4, 6B, 9V, 14, 18C, 19F, and 23F have been responsible for approximately 80% of invasive pneumococcal disease in children <6 years of age in the US.15 These 7 serotypes also accounted for 74% of PNSP and 100% of pneumococci with high level penicillin resistance isolated from children <6 years with invasive disease during a 1993-1994 surveillance by the CDC.19
Efficacy was assessed in a randomized, double-blinded clinical trial in a multiethnic population at Northern California Kaiser Permanente (NCKP) from October 1995 through August 20, 1998, in which 37,816 infants were randomized to receive either Prevnar® or a control vaccine (an investigational meningococcal group C conjugate vaccine [MnCC]) at 2, 4, 6, and 12-15 months of age. Prevnar® was administered to 18,906 children and the control vaccine to 18,910 children. Routinely recommended vaccines were also administered which changed during the trial to reflect changing AAP and Advisory Committee on Immunization Practices (ACIP) recommendations. A planned interim analysis was performed upon accrual of 17 cases of invasive disease due to vaccine-type S. pneumoniae (August 1998). Ancillary endpoints for evaluation of efficacy against pneumococcal disease were also assessed in this trial.
Invasive disease was defined as isolation and identification of S. pneumoniae from normally sterile body sites in children presenting with an acute illness consistent with pneumococcal disease. Weekly surveillance of listings of cultures from the NCKP Regional Microbiology database was conducted to assure ascertainment of all cases. The primary endpoint was efficacy against invasive pneumococcal disease due to vaccine serotypes. The per protocol analysis of the primary endpoint included cases which occurred ≥14 days after the third dose. The intent-to-treat (ITT) analysis included all cases of invasive pneumococcal disease due to vaccine serotypes in children who received at least one dose of vaccine. Secondary analyses of efficacy against all invasive pneumococcal disease, regardless of serotype, were also performed according to these same per protocol and ITT definitions. Results of these analyses are presented in Table 1.
|Prevnar® Number of Cases||Control* Number of Cases||Efficacy||95% CI|
|Per protocol||0||17||100%||75.4, 100|
|All pneumococcal serotypes|
|Per protocol||2||20||90.0%||58.3, 98.9|
|* Investigational meningococcal group C conjugate vaccine (MnCC). † Includes one case in an immunocompromised subject.|
All 22 cases of invasive disease due to vaccine serotype strains in the ITT population were bacteremic. In addition, the following diagnoses were also reported: meningitis (2), pneumonia (2), and cellulitis (1).
Data accumulated through an extended follow-up period to April 20, 1999, resulted in a similar efficacy estimate (Per protocol: 1 case in Pneumococcal 7-valent Conjugate Vaccine (Diphtheria CRM197 Protein), Prevnar® group, 39 cases in control group; ITT: 3 cases in Prevnar® group, 49 cases in the control group).21
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