CLINICAL PHARMACOLOGY
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
Results Of Clinical Evaluations
Efficacy Against Invasive Disease
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.
TABLE 1 : Efficacy of Prevnar Against Invasive Disease
Due to S. pneumoniae in Cases Accrued From October 15, 1995 Through
August 20, 199820,21
|
Prevnar® Number of Cases |
Control* Number of Cases |
Efficacy |
95% CI |
Vaccine serotypes |
Per protocol |
0 |
17 |
100% |
75.4, 100 |
Intent-to-treat |
0 |
22 |
100% |
81.7, 100 |
All pneumococcal serotypes |
Per protocol |
2 |
20 |
90.00% |
58.3, 98.9 |
Intent-to-treat |
3 |
27f |
88.90% |
63.8, 97.9 |
* 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
Efficacy Against Otitis Media
The efficacy of Prevnar® against
otitis media was assessed in two clinical trials: a trial in Finnish infants at
the National Public Health Institute and the invasive disease efficacy trial in
US infants at Northern California Kaiser Permanente (NCKP).
The trial in Finland was a
randomized, double-blind trial in which 1,662 infants were equally randomized
to receive either Prevnar® or a control vaccine (Hepatitis B vaccine
[Hep B]) at 2, 4, 6, and 12-15 months of age. All infants received a Diphtheria
Tetanus Pertussis Vaccine -Haemophilus influenzae type b vaccine
(DTP-Hib) combination vaccine concurrently at 2, 4, and 6 months of age, and
Inactivated Poliovirus Vaccine (IPV) concurrently at 12 months of age. Parents
of study participants were asked to bring their children to the study clinics
if the child had respiratory infections or symptoms suggesting acute otitis
media (AOM). If AOM was diagnosed, tympanocentesis was performed, and the
middle ear fluid was cultured. If S. pneumoniae was isolated, serotyping
was performed.
AOM was defined as a visually
abnormal tympanic membrane suggesting effusion in the middle ear cavity,
concomitantly with at least one of the following symptoms of acute infection:
fever, ear ache, irritability, diarrhea, vomiting, acute otorrhea not caused by
external otitis, or other symptoms of respiratory infection. A new visit
or “episode” was defined as a visit with a study physician at which time a
diagnosis of AOM was made and at least 30 days had elapsed since any previous
visit for otitis media. The primary endpoint was efficacy against AOM episodes
caused by vaccine serotypes in the per protocol population.
In the NCKP invasive disease efficacy trial, the
effectiveness of Prevnar® in reducing the incidence of otitis media
was assessed from the beginning of the trial in October 1995 through April
1998. During this time, 34,146 infants were randomized to receive either Prevnar® (N=17,070), or the control, an investigational meningococcal group C
conjugate vaccine (N=17,076), at 2, 4, 6, and 12-15 months of age.
Physician visits for otitis media were identified by
physician coding of outpatient encounter forms. Because visits may have
included both acute and follow-up care, a new visit or “episode” was defined as
a visit that was at least 21 days following a previous visit for otitis media
(at least 42 days, if the visit appointment was made > 3 days in advance).
Data on placement of ear tubes were collected from automated databases. No
routine tympanocentesis was performed, and no standard definition of otitis
media was used by study physicians. The primary otitis media endpoint was
efficacy against all otitis media episodes in the per protocol population.
Table 2 presents the per protocol and intent-to-treat
results of key otitis media analyses for both studies. The per protocol
analyses include otitis media episodes that occurred ≥ 14 days after the
third dose. The intent-to-treat analyses include all otitis media episodes in
children who received at least one dose of vaccine.
TABLE 2 Efficacy of Prevnar® Against Otitis
Media in the Finnish and NCKP Trials20,21,22,23
|
Per Protocol |
Intent-to-Treat |
Vaccine Efficacy Estimate* |
95% Confidence Interval |
Vaccine Efficacy Estimate* |
95% Confidence Interval |
Finnish Trial |
N=1632 |
N=1662 |
AOM due to Vaccine Serotypes |
57% |
44, 67 |
54% |
41, 64 |
All culture-confirmed pneumococcal AOM regardless of serotype |
34% |
21, 45 |
32% |
19, 42 |
NCKP Trial |
N=23,746 |
N=34,146 |
All Otitis Media Episodes regardless of etiology† |
7% |
4, 10 |
6% |
4, 9 |
* All vaccine efficacy
estimates in the table are statistically significant.
† The vaccine efficacy against all AOM episodes in the Finnish
trial, while not reaching statistical significance, was 6% (95% CI: -4, 16) in
the per protocol population and 4% (95% CI: -7, 14) in the intent-to-treat
population. |
The vaccine efficacy against
AOM episodes due to vaccine-related serotypes (6A, 9N, 18B, 19A, 23A), also
assessed in the Finnish trial, was 51% (95% CI: 27, 67) in the per protocol
population and 44% (95% CI: 20, 62) in the intent-to-treat population. The
vaccine efficacy against AOM episodes caused by serotypes unrelated to the
vaccine was -33% (95% CI: -80, 1) in the per protocol population and -39% (95%
CI: -86, -3) in the intent-to-treat population, indicating that children who
received Prevnar® appear to be at increased risk of otitis media due
to pneumococcal serotypes not represented in the vaccine, compared to children
who received the control vaccine. However, vaccination with Prevnar® reduced
pneumococcal otitis media episodes overall.
Several other otitis media
endpoints were also assessed in the two trials. Recurrent AOM, defined as 3
episodes in 6 months or 4 episodes in 12 months, was reduced by 9% in both the
per protocol and intent-to-treat populations (95% CI: 3, 15 in per protocol and
95% CI: 4, 14 in intent-to-treat) in the NCKP trial. This observation was supported
by a similar trend, although not statistically significant, seen in the Finnish
trial. The NCKP trial also demonstrated a 20% reduction (95% CI: 2, 35) in the
placement of tympanostomy tubes in the per protocol population and a 21%
reduction (95% CI: 4, 34) in the intent-to-treat population.
Data from the NCKP trial accumulated through an extended
follow-up period to April 20, 1999, in which a total of 37,866 children were
included (18,925 in Prevnar® group and 18,941 in MnCC control
group), resulted in similar otitis media efficacy estimates for all endpoints.24
Immunogenicity
Routine Schedule
Subjects from a subset of selected study sites in the
NCKP efficacy study were approached for participation in the immunogenicity
portion of the study on a volunteer basis. Immune responses following three or
four doses of Prevnar® or the control vaccine were evaluated in
children who received either concurrent Diphtheria and Tetanus Toxoids and
Pertussis Vaccine Adsorbed and Haemophilus b Conjugate Vaccine (Diphtheria CRM197
Protein Conjugate), (DTP-HbOC), or Diphtheria and Tetanus Toxoids and Acellular
Pertussis Vaccine Adsorbed (DTaP), and Haemophilus b Conjugate Vaccine
(Diphtheria CRM197 Protein Conjugate), (HbOC) vaccines at 2, 4, and
6 months of age. The use of Hepatitis B (Hep B), Oral Polio Vaccine (OPV),
Inactivated Polio Vaccine (IPV), Measles-Mumps-Rubella (MMR), and Varicella
vaccines were permitted according to the AAP and ACIP recommendations.
Table 3 presents the geometric mean concentrations (GMC)
of pneumococcal antibodies following the third and fourth doses of Prevnar® or the control vaccine when administered concurrently with DTP-HbOC
vaccine in the efficacy study.
TABLE 3 : Geometric Mean Concentrations (μg/mL) of
Pneumococcal Antibodies Following the Third and Fourth Doses of Prevnar® or
Control* When Administered Concurrently With DTP- HbOC in the Efficacy Study20,21
Serotype |
Post dose 3 GMC† (95% CI for Prevnar®) |
Post dose 4 GMC‡ (95% CI for Prevnar®) |
Prevnar®§ |
Control* |
Prevnar®§ |
Control* |
|
N=88 |
N=92 |
N=68 |
N=61 |
4 |
1.46
(1.19, 1.78) |
0.03 |
2.38 (1.88,3.03) |
0.04 |
6B |
4.70
(3.59, 6.14) |
0.08 |
14.45 (11.17, 18.69) |
0.17 |
9V |
1.99
(1.64, 2.42) |
0.05 |
3.51 (2.75, 4.48) |
0.06 |
14 |
4.60
(3.70, 5.74) |
0.05 |
6.52 (5.18, 8.21) |
0.06 |
18C |
2.16
(1.73, 2.69) |
0.04 |
3.43 (2.70, 4.37) |
0.07 |
19F |
1.39
(1.16, 1.68) |
0.09 |
2.07 (1.66, 2.57) |
0.18 |
23F |
1.85
(1.46, 2.34) |
0.05 |
3.82 (2.85, 5.11) |
0.09 |
* Control was investigational
meningococcal group C conjugate vaccine (MnCC).
† Mean age of Prevnar® group was 7.8 months and of
control group was 7.7 months. N is slightly less for some serotypes in each
group.
‡ Mean age of Prevnar® group was 14.2 months and of
control group was 14.4 months. N is slightly less for some serotypes in each
group.
§ p < 0.001 when Prevnar® compared to control for each
serotype using a Wilcoxon's test. |
In another randomized study
(Manufacturing Bridging Study, 118-16), immune responses were evaluated
following three doses of Pneumococcal 7-valent Conjugate Vaccine (Diphtheria
CRM197 Protein), Prevnar® administered concomitantly with
DTaP and HbOC vaccines at 2, 4, and 6 months of age, IPV at 2 and 4 months of
age, and Hep B at 2 and 6 months of age. The control group received concomitant
vaccines only. Table 4 presents the immune responses to pneumococcal
polysaccharides observed in both this study and in the subset of subjects from
the efficacy study that received concomitant DTaP and HbOC vaccines.
TABLE 4 :Geometric Mean Concentrations (μg/mL) of
Pneumococcal Antibodies Following the Third Dose of Prevnar® or
Control* When Administered Concurrently With DTaP and HbOC in the Efficacy
Study† and Manufacturing Bridging Study20,21,25
Serotype |
Efficacy Study |
Manufacturing Bridging Study |
Post dose 3 GMC‡ (95% CI for Prevnar®) |
Post dose 3 GMC§ (95% CI for Prevnar®) |
Prevnar®|| |
Control* |
Prevnar®|| |
Control* |
|
N=32 |
N=32 |
N=159 |
N=83 |
4 |
1.47
(1.08, 2.02) |
0.02 |
2.03 (1.75, 2.37) |
0.02 |
6B |
2.18
(1.20, 3.96) |
0.06 |
2.97 (2.43, 3.65) |
0.07 |
9V |
1.52
(1.04, 2.22) |
0.04 |
1.18 (1.01, 1.39) |
0.04 |
14 |
5.05
(3.32, 7.70) |
0.04 |
4.64 (3.80, 5.66) |
0.04 |
18C |
2.24
(1.65, 3.02) |
0.04 |
1.96 (1.66, 2.30) |
0.04 |
19F |
1.54
(1.09, 2.17) |
0.1 |
1.91 (1.63, 2.25) |
0.08 |
23F |
1.48
(0.97, 2.25) |
0.05 |
1.71 (1.44, 2.05) |
0.05 |
* Control in efficacy study was
investigational meningococcal group C conjugate vaccine (MnCC) and in
Manufacturing Bridging Study was concomitant vaccines only.
† Sufficient data are not available to reliably assess GMCs
following 4 doses of Prevnar® when administered with DTaP in the
NCKP efficacy study.
‡ Mean age of the Prevnar® group was 7.4 months and of
the control group was 7.6 months. N is slightly less for some serotypes in each
group.
§ Mean age of the Prevnar® group and the control group
was 7.2 months.
|| p < 0.001 when Prevnar® compared to control for each
serotype using a Wilcoxon's test in the efficacy study and two-sample t-test in
the Manufacturing Bridging Study. |
In all studies in which the
immune responses to Prevnar® were contrasted to control, a
significant antibody response was seen to all vaccine serotypes following three
or four doses, although geometric mean concentrations of antibody varied among
serotypes.20,21,23,25,26,27,28,29,30 The minimum serum antibody
concentration necessary for protection against invasive pneumococcal disease or
against pneumococcal otitis media has not been determined for any serotype.
Prevnar® induces functional antibodies to all vaccine
serotypes, as measured by opsonophagocytosis following three doses.30
Previously Unvaccinated Older Infants And Children
To determine an appropriate schedule for children 7
months of age or older at the time of the first immunization with Prevnar®,
483 children in 4 ancillary studies received Prevnar® at various
schedules and were evaluated for immunogenicity. GMCs attained using the
various schedules among older infants and children were comparable to immune
responses of children, who received concomitant DTaP, in the NCKP efficacy
study (118-8) after 3 doses for most serotypes, as shown in Table 5. These data
support the schedule for previously unvaccinated older infants and children who
are beyond the age of the infant schedule. For usage in older infants and
children, see DOSAGE AND ADMINISTRATION.
TABLE 5 : Geometric Mean Concentrations (μg/mL)
of Pneumococcal Antibodies Following Immunization of Children From 7 Months
Through 9 Years of Age With Prevnar® 31
Age group, Vaccinations |
Study |
Sample Size(s) |
4 |
6B |
9V |
14 |
18C |
19F |
23F |
7-11 mo. 3 doses |
118-12 |
22 |
2.34 |
3.66 |
2.11 |
9.33 |
2.31 |
1.6 |
2.5 |
|
118-16 |
39 |
3.6 |
4.63 |
2.04 |
5.48 |
1.98 |
2.15 |
1.93 |
12-17 mo. 2 doses |
118-15* |
82-84† |
3.91 |
4.67 |
1.94 |
6.92 |
2.25 |
3.78 |
3.29 |
|
118-18 |
33 |
7.02 |
4.25 |
3.26 |
6.31 |
3.6 |
3.29 |
2.92 |
18-23 mo. 2 doses |
118-15* |
52-54† |
3.36 |
4.92 |
1.8 |
6.69 |
2.65 |
3.17 |
2.71 |
|
118-18 |
45 |
6.85 |
3.71 |
3.86 |
6.48 |
3.42 |
3.86 |
2.75 |
24-35 mo. 1 dose |
118-18 |
53 |
5.34 |
2.9 |
3.43 |
1.88 |
3.03 |
4.07 |
1.56 |
36-59 mo. 1 dose |
118-18 |
52 |
6.27 |
6.4 |
4.62 |
5.95 |
4.08 |
6.37 |
2.95 |
5-9 yrs. 1 dose |
118-18 |
101 |
6.92 |
20.84 |
7.49 |
19.32 |
6.72 |
12.51 |
11.57 |
118-8, DTaP |
Post dose 3 |
31-32† |
1.47 |
2.18 |
1.52 |
5.05 |
2.24 |
1.54 |
1.48 |
Bold = GMC not inferior to
118-8, DTaP post dose 3 (one-sided lower limit of the 95% CI of GMC ratio
≥ 0.50).
* Study in Navajo and Apache populations.
† Numbers vary with serotype. |
REFERENCES
1. Schuchat A, Robinson K, Wenger JD, et al. Bacterial meningitis in the United States in 1995. N Engl J Med. 1997; 337:970-6.
2. Zangwill KM, Vadheim CM, Vannier AM, et al. Epidemiology of invasive pneumococcal disease in Southern California: implications for the design and conduct of a pneumococcal conjugate vaccine efficacy trial. J Infect is. 1996; 174:752-9.
3. Breiman R, Spika J, Navarro V, et al. Pneumococcal bacteremia in Charleston County, South Carolina. Arch Intern Med. 1990; 150:1401-5.
4. Levine O, Farley M, Harrison LH, et al. Risk factors for invasive pneumococcal disease in children: a population-based case-control study in North America. Pediatrics. 1999; 103:1-5.
5. Kaplan SL, Mason EO, Barson WJ, et al. Three-year multicenter surveillance of systemic pneumococcal infections in children. Pediatrics. 1998; 102:538-44.
6. Arditi M, Mason E, Bradley J, et al. Three-year multicenter surveillance of pneumococcal meningitis in children: clinical characteristics and outcome related to penicillin susceptibility and dexamethasone use. Pediatrics. 1998; 102:1087-97.
7. Shappert SM. Ambulatory care visits to physician offices, hospital outpatient departments, and emergency departments: United States, 1997. National Center for Health Statistics. Vital Health Sat. 1999; 13(143):1-41.
8. Hall MJ, Lawrence L. Ambulatory surgery in the United States, 1996. Adv Data Vital Health Stat. 1998; 300:1-16.
9. Teele DW, Klein JO, Rosner B, et al. Epidemiology of otitis media during the first seven years of life in children in greater Boston: a prospective, cohort study. J Infect Dis. 1989; 160:83-94.
10. Shappert, SM. Office visits for otitis media: United States, 1975-1990. Adv Data Vital Health Stat. 1992; 214:1-20.
11. Bluestone CD, Stephenson BS, Martin LM. Ten-year review of otitis media pathogens. Pediatr Infect Dis J. 1992; 11:S7-S11.
12. Giebink GS. The microbiology of otitis media. Pediatr Infect Dis J. 1989; 8:S18-S20.
13. Rodriguez WJ, Schwartz RH. Streptococcus pneumoniae causes otitis media with higher fever and more redness of tympanic membrane than Haemophilus influenzae or Moraxella catarrhalis. Pediatr Infect Dis J. 1999; 18:942-4.
14. Barnett ED, Klein JO. The problem of resistant bacteria for the management of acute otitis media. Ped Clin North Am. 1995; 42:509-17.
15. Butler JC, Breiman RF, Lipman HB, et al. Serotype distribution of Streptococcus pneumoniae infections among preschool children in the United States, 1978-1994: implications for development of a conjugate vaccine. J Infect Dis. 1995; 171:885-9.
16. Paisley JW, Lauer BA, McIntosh K, et al. Pathogens associated with acute lower respiratory tract infection in young children. Pediatr Infect Dis J. 1984; 3:14-9.
17. American Academy of Pediatrics Committee on Infectious Diseases. Therapy for children with invasive pneumococcal infections. Pediatrics. 1997; 99:289-300.
18. Hausdorff WP, Bryant J, Paradiso PR, Siber GR. Which pneumococcal serogroups cause the most invasive disease: implications for conjugate vaccine formulation and use, part I. Clin Infect Dis. 2000; 30:100-21.
19. Butler JC, Hoffman J, Cetron MS, et al. The continued emergence of drug-resistant Streptococcus pneumoniae in the United States. An Update from the Centers for Disease Control and Prevention's Pneumococcal Sentinel Surveillance System. J Infect Dis. 1996; 174:986-93.
20. Lederle Laboratories, Data on File: D118-P8.
21. Black S, Shinefield H, Ray P, et al. Efficacy, safety and immunogenicity of heptavalent pneumococcal conjugate vaccine in children. Pediatr Infect Dis J. 2000; 19:187-195.
22. Lederle Laboratories, Data on File: D118-P809.
23. Eskola J, Kilpi T, Palma A, et al. Efficacy of a pneumococcal conjugate vaccine against acute otitis media. N Engl J Med. 2001; 344:403-409.
24. Fireman B, Black S, Shinefield H, et al. The impact of the pneumococcal conjugate vaccine on otitis media. Pediatr Infect Dis J. 2003;22:10-16.
25. Lederle Laboratories, Data on File: D118-P16.
26. Lederle Laboratories, Data on File: D118-P8 Addendum DTaP Immunogenicity.
27. Shinefield HR, Black S, Ray P. Safety and immunogenicity of heptavalent pneumococcal CRM197 conjugate vaccine in infants and toddlers. Pediatr Infect Dis J. 1999; 18:757-63.
28. Lederle Laboratories, Data on File: D118-P12.
29. Rennels MD, Edwards KM, Keyserling HL, et al. Safety and immunogenicity of heptavalent pneumococcal vaccine conjugated to CRM197 in United States infants. Pediatrics. 1998; 101(4):604-11.
30. Lederle Laboratories, Data on File: D118-P3.
31. Lederle Laboratories, Data on File: Integrated Summary on Catch-Up.