Disease Burden of Invasive Meningococcal Disease in the Netherlands Between June 1999 and June 2011: A Subjective Role for Serogroup and Clonal Complex.

BACKGROUND: Several countries consider the implementation of a meningococcal serogroup B vaccine for young children and/or serogroup C or ACWY conjugate vaccine for adolescents. Representative information on clinical course of invasive meningococcal disease (IMD) is useful to evaluate cost-effectiveness of vaccination. Information on the relation between infecting meningococcal clonal complex (CC), disease course and outcome of IMD is scarce. METHODS: A retrospective study using Dutch surveillance data on IMD from June 1999 to June 2011. Clinical information was retrieved from hospital records. The effect of age, comorbidity, clinical manifestation, serogroup, and CC on disease course and outcome was assessed in multivariable analyses. Meningococcal CCs were assessed by multilocus sequence typing. RESULTS: Clinical information was retrieved for 879 IMD cases: 48% of patients presented with meningitis, 17% with septic shock, and 22% with septic shock plus meningitis. Development of septic shock was not related to CC or serogroup. Median (interquartile range) duration of hospital admission was 10 (8-13) days. Intensive care unit admittance (38%) was higher for patients aged ≥10 years and patients with septic shock (P-values ≤.001). Case-fatality rate (8%) and development of sequelae (29%) was dependent on age and clinical manifestation (P-values ≤.001) and not affected by comorbidity, CC, or serogroup. CONCLUSIONS: IMD still coincides with a considerable disease burden and mortality. Disease course and outcome depend mainly on age and clinical manifestation and less on meningococcal CC or serogroup.

Levels and functionality of antibodies after pneumococcal conjugate vaccine in schedules with different timing of the booster dose.

The seven-valent pneumococcal conjugate vaccine (PCV7) has been introduced in most high-income countries, although with differences in age, timing and number of primary doses before 6 months of age and presence and timing of a booster vaccination. The objective was to determine and compare the IgG antibody levels and functionality of IgG responses (avidity and opsonophagocytoses) at 1 and 2 years of age following 2 primary doses with a booster at 11 or 24 months of age. Children received PCV7 at 2 and 4 months (2-dose group), or at 2, 4 and 11 months (2+1-dose group), or no PCV7 (controls) before 1 year of age. All children received a PCV7 dose at 24 months of age. At the age of 12 months, the 2+1-dose group had higher IgG levels and functional antibody levels, compared to the 2-dose group for all serotypes, but at 25 months the difference between the 2-dose and 2+1-dose groups had disappeared for most serotypes. The kinetics of opsonophagocytic antibodies were in line with the specific IgG antibody levels for most serotypes, although differences between the 2-dose and the 2+1-dose group were more pronounced in OPA activity as compared to the IgG levels especially at the age of 24 months. Delaying the booster dose from 11 months to 24 months after 2 primary doses resulted in significantly higher OPA GMTs one month after the booster dose. This must, however, be balanced against the risk of leaving children unboosted between the age of 11 and 24 months at a time when disease risk is still high. Local decisions about the timing of a booster dose should also take into account vaccine coverage and the indirect herd effect in a well vaccinated population. Trial registration clinicaltrials.gov Identifier: NCT00189020.

Perceived discomfort levels in healthy children participating in vaccine research.

When assessing the risks of a research protocol, review boards need to consider not only the possible harms but also the expected discomfort levels caused by the various study procedures. However, data on how children experience various study procedures are scarce. This study assessed perceived discomfort levels in 671 healthy children aged 0-2 years under-going vaccinations, venipunctures, and nasopharyngeal swab taking. In half of the study participants, venipunctures caused a moderate or high level of discomfort (49%). Corresponding figures for nasopharyngeal swabbing and vaccinations were 28% and 12%, respectively. Within the reported age group, increasing age was related with higher discomfort levels. In a majority of cases for all study procedures, the perceived levels of discomfort met the parents' expectations.

Prevalence and clinical course in invasive infections with meningococcal endotoxin variants.

BACKGROUND: Meningococci produce a penta-acylated instead of hexa-acylated lipid A when their lpxL1 gene is inactivated. Meningococcal strains with such lipid A endotoxin variants have been found previously in adult meningitis patients, where they caused less blood coagulopathy because of decreased TLR4 activation. METHODS: A cohort of 448 isolates from patients with invasive meningococcal disease in the Netherlands were screened for the ability to induce IL-6 in monocytic cell Mono Mac 6 cells. The lpxL1 gene was sequenced of isolates, which show poor capacity to induce IL-6.. Clinical characteristics of patients were retrieved from hospital records. RESULTS: Of 448 patients, 29 (6.5%) were infected with meningococci expressing a lipid A variant strain. Lipid A variation was not associated with a specific serogroup or genotype. Infections with lipid A variants were associated with older age (19.3 vs. 5.9 (median) years, p = 0.007) and higher prevalence of underlying comorbidities (39% vs. 17%; p = 0.004) compared to wild-type strains. Patients infected with lipid A variant strains had less severe infections like meningitis or shock (OR 0.23; 95%CI 0.09-0.58) and were less often admitted to intensive care (OR 0.21; 95%CI 0.07-0.60) compared to wild-type strains, independent of age, underlying comorbidities or strain characteristics. CONCLUSIONS: In adults with meningococcal disease lipid A variation is rather common. Infection with penta-acylated lipid A variant meningococci is associated with a less severe disease course.

Salivary immune responses to the 7-valent pneumococcal conjugate vaccine in the first 2 years of life.

BACKGROUND: The CRM197-conjugated 7-valent pneumococcal vaccine (PCV7) is protective against vaccine serotype disease and nasopharyngeal carriage. Data on PCV7-induced mucosal antibodies in relation to systemic or natural anticapsular antibodies are scarce. METHODS: In a randomized controlled setting, children received PCV7 at age 2 and 4 months (2-dose group), at age 2, 4 and 11 months (2+1-dose group) or no PCV7 (control group). From 188 children paired saliva samples were collected at 12 and 24 months of age. From a subgroup of 15 immunized children also serum samples were collected. IgG and IgA antibody-levels were measured by multiplex immunoassay. RESULTS: At 12 months, both vaccine groups showed higher serum and saliva IgG-levels against vaccine serotypes compared with controls which sustained until 24 months for most serotypes. Salivary IgG-levels were 10-20-fold lower compared to serum IgG, however, serum and saliva IgG-levels were highly correlated. Serum and salivary IgA-levels were higher in both vaccine groups at 12 months compared with controls, except for serotype 19F. Higher salivary IgA levels remained present for most serotypes in the 2+1-dose group until 24 months, but not in the 2-dose group. Salivary IgA more than IgG, increased after documented carriage of serotypes 6B, 19F and 23F In contrast to IgG, salivary IgA-levels were comparable with serum, suggesting local IgA-production. CONCLUSIONS: PCV7 vaccination results in significant increases in salivary IgG and IgA-levels, which are more pronounced for IgG when compared to controls. In contrast, salivary anticapsular IgA-levels seemed to respond more to natural boosting. Salivary IgG and IgA-levels correlate well with systemic antibodies, suggesting saliva might be useful as potential future surveillance tool.

Effect of 7-valent pneumococcal conjugate vaccine on nasopharyngeal carriage with Haemophilus influenzae and Moraxella catarrhalis in a randomized controlled trial.

Seven-valent CRM197-conjugated pneumococcal conjugate vaccine (PCV7(CRM197)) reduces both vaccine serotype nasopharyngeal colonization and vaccine serotype acute otitis media by 50-60%. However, overall pneumococcal carriage and impact on otitis media are partly offset by concomitant increase of nonvaccine serotypes. We investigated in a randomized controlled trial the impact of 2-doses and 2+1-doses of PCV7(CRM197) on carriage of Streptococcus pneumoniae and of other nasopharyngeal commensals and well-known otitis media pathogens, Haemophilus influenzae and Moraxella catarrhalis, in children. Nasopharyngeal swabs were collected at the age of 6 weeks and at 6, 12, 18 and 24 months. We observed high carriage rates up to 68% for S. pneumoniae, 71% for H. influenzae and 68% for M. catarrhalis at the age of 18 months. Reduced dose (CRM197) schedules induced a slight reduction in overall pneumococcal carriage but no increases in the presence of H. influenzae and M. catarrhalis.

Lower immunoglobulin G antibody responses to pneumococcal conjugate vaccination at the age of 2 years after previous nasopharyngeal carriage of Streptococcus pneumoniae.

OBJECTIVE: To determine whether nasopharyngeal pneumococcal carriage with serotypes 6B, 19F, or 23F interferes with immunoglobulin G (IgG) antibody responses to vaccination with 7-valent pneumococcal conjugate vaccine (PCV7) at the age 24 months. STUDY DESIGN: Blood samples were collected before and after a PCV7 challenge vaccination at age 24 months from subsets of children participating in a randomized controlled trial. Children previously had received two doses of PCV7 at 2 and 4 months, two plus one doses of PCV7 at 2, 4, and 11 months, or no dosage until 24 months. Nasopharyngeal swabs were cultured at for Streptococcus pneumoniae at age 6 weeks and at 6, 12, 18, and 24 months. IgG responses were determined with enzyme immunoassay. RESULTS: Lower IgG responses against serotypes 6B, 19F, and 23F were observed on PCV7 challenge vaccination at 24 months in children who had received earlier PCV7 vaccinations and had been found positive for homologous carriage compared with non-carriers of these serotypes. Lower non-homologous IgG responses were observed after the PCV7 challenge at 24 months against serotype 6B after earlier 19F carriage and against serotype 19F after earlier 23F carriage compared with children who had not been positive for carriage of these serotypes. CONCLUSIONS: Pneumococcal colonization with serotypes 6B, 19F, and 23F is associated with diminished immune responses against these serotypes on PCV7 vaccination at 2 years of age. Underlying mechanisms deserve further investigation.

Effect of seven-valent pneumococcal conjugate vaccine on Staphylococcus aureus colonisation in a randomised controlled trial.

BACKGROUND: Heptavalent pneumococcal conjugate vaccine (PCV7) shifts nasopharyngeal colonisation with vaccine serotype pneumococci towards nonvaccine serotypes. Because of the reported negative association of vaccine serotype pneumococci and Staphylococcus aureus in the nasopharynx, we explored the effect of PCV7 on nasopharyngeal colonisation with S. aureus in children and parents. METHODOLOGY/PRINCIPAL FINDINGS: This study was part of a randomised controlled trial on the effect of PCV7 on pneumococcal carriage, enrolling healthy newborns who were randomly assigned (1:1:1) to receive PCV7 (1) at 2 and 4 months of age (2) at 2, 4 and 11 months or (3) no PCV7 (controls). Nasopharyngeal colonisation of S. aureus was a planned secondary outcome. Nasopharyngeal swabs were obtained from all children over a 2-year period with 6-months interval and from one parent at the child's age of 12 and 24 months and cultured for Streptococcus pneumoniae and S. aureus. Between July 2005 and February 2006, 1005 children were enrolled and received either 2-doses of PCV7 (n = 336), 2+1-doses (336) or no dose (n = 333) before PCV7 implementation in the Dutch national immunization program. S. aureus colonisation had doubled in children in the 2+1-dose group at 12 months of age compared with unvaccinated controls (10.1% versus 5.0%; p = 0.019). A negative association for co-colonisation of S. pneumoniae and S. aureus was observed for both vaccine serotype (adjusted odds ratio (aOR) 0.53, 95% confidence interval (CI) 0.38-0.74) and nonvaccine serotype pneumococci (aOR 0.67, 95% CI 0.52-0.88). CONCLUSIONS/SIGNIFICANCE: PCV7 induces a temporary increase in S. aureus colonisation in children around 12 months of age after a 2+1-dose PCV7 schedule. The potential clinical consequences are unknown and monitoring is warranted. TRIAL REGISTRATION: ClinicalTrials.gov NCT00189020.

Nontypeable Haemophilus influenzae invasive disease in The Netherlands: a retrospective surveillance study 2001-2008.

BACKGROUND: Nontypeable (unencapsulated) strains of Haemophilus influenzae (ntHi) are usually involved in respiratory tract infections and otitis media but may also cause invasive disease. The epidemiology, the course of disease, and the outcome of ntHi invasive disease are not well established. For prevention, risk groups that might benefit from vaccination have to be defined. METHODS: All patients with ntHi invasive disease confirmed by culture of samples collected by the Netherlands Reference Laboratory for Bacterial Meningitis from 41 sentinel hospitals and representative of ∼45% of all Dutch hospitalized ntHi case patients over the period from 2001 through 2008 were included in the study. Data on clinical presentation, course of disease, and outcome as well as patient characteristics and comorbidity were retrospectively retrieved from hospital records. RESULTS: Clinical presentations of 396 cases included mainly invasive pneumonia (190 cases [48%]) and bacteremia without a clinical focus (75 cases [19%]). Comorbidities were present in 327 [83%] and immunodeficiency in 173 [44%] of all cases. The overall case fatality rate within the first month after diagnosis was 12% and the lowest (2%) was among patients aged 5-54 years. The highest extrapolated age-specific incidence rates occurred within the first 6 weeks of life (19.0 cases per 100,000 persons), concerning mostly prematurely born infants with bacteremia within 24 h after birth, and in the first year of life (5.6 cases per 100,000 persons). The highest rate in adults was among elderly patients aged >65 years (2.2 cases per 100,000 persons). CONCLUSIONS: This study provides a detailed overview of invasive ntHi disease cases in the Netherlands. Risk groups are prematurely born infants, elderly patients aged >65 years, and immunocompromised patients.

Hospitalization due to varicella in the Netherlands.

BACKGROUND: In the Netherlands, incidence of physician's consultations and hospitalizations for varicella is low compared to other countries. Better knowledge about the severity of varicella among Dutch hospitalized patients is needed. Therefore, a medical record research was conducted among hospitalized patients with diagnosis varicella. METHODS: Hospital admissions due to varicella in 2003-2006 were obtained from the National Medical Register. Retrospectively, additional data were retrieved from the medical record of patients hospitalized with varicella in 23 Dutch hospitals using a standardized form. Analyses were performed using descriptive statistics. RESULTS: The study population (N = 296) was representative for all varicella admissions in the Netherlands (N = 1,658) regarding age, sex, duration of admission and type of diagnosis. Complications were recorded in 76% of the patients (37% had at least one relatively severe complication). Bacterial super infections of skin lesions (28%), (imminent) dehydration (19%), febrile convulsions (7%), pneumonia (7%) and gastroenteritis (7%) were most frequently reported. No varicella-related death occurred within the study population and 3% of the patients had serious rest symptoms. CONCLUSIONS: It is not likely that the severity of varicella among hospitalized patients in the Netherlands differs from other countries. A considerable part of the varicella complications among hospitalized patients was rather moderate and can be treated effectively, although in a third of the hospitalized cases with complications, severe complications occurred. These data are relevant in the decision-making process regarding whether or not to introduce routine varicella vaccination in the Netherlands.

Pneumococcal conjugate vaccination and nasopharyngeal acquisition of pneumococcal serotype 19A strains.

CONTEXT: The rapid increase in multiresistant serotype 19A as a cause of invasive and respiratory pneumococcal disease has been associated in time with the widespread implementation of 7-valent pneumococcal conjugate vaccination (PCV-7) in several countries. Because spontaneous fluctuations in time and antibiotic selective pressure may have induced this serotype 19A increase, controlled studies are needed to assess the role of PCV-7. OBJECTIVE: To examine the association of PCV-7 vaccination and nasopharyngeal acquisition of serotype 19A pneumococci, their clonal distribution, and antibiotic susceptibility. DESIGN, SETTING, AND PATIENTS: Post hoc per-protocol completer's analysis as part of a randomized controlled trial of nasopharyngeal Streptococcus pneumoniae carriage enrolling 1003 healthy newborns with follow-up to the age of 24 months in The Netherlands, which has low antibiotic resistance rates. The study was conducted before widespread PCV-7 implementation in infants, between July 7, 2005, and February 14, 2008. Nasopharyngeal swabs were obtained at the age of 6 weeks and at 6, 12, 18, and 24 months. INTERVENTION: Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (unvaccinated control group). MAIN OUTCOME MEASURE: Cumulative proportion of children with nasopharyngeal acquisition of a new serotype 19A strain from 6 through 24 months of age. RESULTS: Nine hundred forty-eight children completed the study. Fifty-four nasopharyngeal serotype 19A carriage isolates from 318 in the 2-dose group, 66 isolates from 327 in the 2 + 1-dose group, and 33 isolates from 303 in the unvaccinated were collected from 6 weeks through 24 months. The cumulative proportion who tested positive for new nasopharyngeal serotype 19A acquisition from 6 through 24 months of age was significantly higher in those having received the 2 + 1-dose PCV-7 schedule (16.2%; 95% confidence interval [CI], 12.6%-20.6%) vs those who were unvaccinated (9.2%; 95% CI, 6.5%-13.0%; relative risk [RR], 1.75; 95% CI, 1.14-2.70) but not after a 2-dose schedule (13.2%; 95% CI, 9.9%-17.4%; RR, 1.43; 95% CI, 0.91-2.25). There were 28 different sequence types identified, including 6 new types. The proportion of children with new 19A acquisition who had used antibiotics in the last 6 months (18.7%) did not differ among groups. Five isolates were penicillin-intermediate susceptible and another 3 were nonsusceptible to erythromycin and azithromycin, all in the vaccine groups. CONCLUSION: A 2 + 1-dose PCV-7 schedule was associated with an increase in serotype 19A nasopharyngeal acquisition compared with unvaccinated controls. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00189020.

Cost effectiveness of pneumococcal vaccination among Dutch infants: economic analysis of the seven valent pneumococcal conjugated vaccine and forecast for the 10 valent and 13 valent vaccines.

OBJECTIVES: To update cost effectiveness estimates for the four dose (3+1) schedule of the seven valent pneumococcal conjugated vaccine (PCV-7) in the Netherlands and to explore the impact on cost effectiveness of reduced dose schedules and implementation of 10 valent and 13 valent pneumococcal vaccines (PCV-10 and PCV-13). DESIGN: Economic evaluation comparing PCV-7, PCV-10, and PCV-13 with no vaccination using a decision tree analytic model built from data in previous studies. SETTING: The Netherlands. Population A cohort of 180,000 newborns followed until 5 years of age. MAIN OUTCOME MEASURES: Costs; gains in life years and quality adjusted life years (QALYs); and incremental cost effectiveness ratios. RESULTS: Under base case assumptions-that is, assuming a five year protective period of the vaccine and no assumed net indirect effects (herd protection minus serotype replacement) among children aged over 5 years-vaccination with PVC-7 in a four dose (3+1) schedule was estimated to prevent 71 and 5778 cases of invasive and non-invasive pneumococcal disease, respectively, in children aged up to 5 years. This corresponds with a total net gain of 173 life years or 277 QALYs. The incremental cost effectiveness ratio of PCV-7 was estimated at euro113,891 ( pound98,300; $145,000) per QALY, well over the ratio of euro50,000 per QALY required for PCV-7 to be regarded as potentially cost effective. A three dose (2+1) schedule of PCV-7 reduced the incremental cost effectiveness ratio to euro82,975 per QALY. For various assumptions and including 10% of the maximum net indirect effects among individuals aged 5 years and over, PCV-10 and PCV-13 had incremental cost effectiveness ratios ranging from euro31,250 to euro52,947 per QALY. CONCLUSIONS: The current Dutch infant vaccination programme of four doses of PCV-7 is not cost effective because of increases in invasive disease caused by non-vaccine serotypes, which reduces the overall direct effects of vaccination and offsets potential positive herd protection benefits in unvaccinated individuals. The 10 valent and 13 valent pneumococcal vaccines could have better net health benefits than PCV-7 through less replacement disease and increased herd protection. Both these effects could substantially reduce the incremental cost effectiveness ratio to possibly acceptable levels, if total programme costs can be lowered by reduced schedules, reductions in vaccine prices, or both.

Effects of pneumococcal conjugate vaccine 2 years after its introduction, the Netherlands.

In the Netherlands, the 7-valent pneumococcal conjugate vaccine (PCV-7) was implemented in a 3+1-dose schedule in the national immunization program for infants born after April 1, 2006. To assess the vaccine's effectiveness, we compared disease incidence before and after vaccine implementation (June 2004-June 2006 and June 2006-June 2008, respectively). We serotyped 2,552 invasive pneumococcal isolates from throughout the Netherlands, covering 25% of the country's population. Clinical characteristics were extracted from hospital records. After June 2006, vaccine-serotype invasive pneumococcal disease (IPD) decreased 90% (95% confidence interval [CI] 68%-97%) in children age eligible for PCV-7; simultaneously, however, non-vaccine-serotype IPD increased by 71% (not significant), resulting in a 44% total net IPD reduction (95% CI 7%-66%). IPD rates did not change for other age groups. In the Netherlands, PCV-7 offered high protection against vaccine-serotype IPD in vaccinated children, but increases of non-vaccine-serotype IPD reduced net vaccine benefits.

Comparability of antibody response to a booster dose of 7-valent pneumococcal conjugate vaccine in infants primed with either 2 or 3 doses.

In this cohort study we compared IgG antibody levels between infants immunized with 7-valent CRM197-conjugated pneumococcal vaccine (PCV-7) at 2, 4 and 11 months and at 2, 3, 4 and 11 months of age, as measured by double adsorption ELISA. Pre- and post-booster levels following the 2+1- and 3+1-dose schedule were comparable for 5 out of 7 serotypes except for serotypes 6B and 19F. The proportion of children reaching post-booster antibody thresholds were comparable except for 6B (>or=1.0 microg/ml and >or=5.0 microg/ml) and 19F (>or=5.0 microg/ml). Surveillance studies are warranted for vaccine impact on 6B and 19F disease cases after reduced-dose PCV-7 schedules.

Effect of reduced-dose schedules with 7-valent pneumococcal conjugate vaccine on nasopharyngeal pneumococcal carriage in children: a randomized controlled trial.

CONTEXT: The effects of reduced-dose schedules of 7-valent pneumococcal conjugate vaccine (PCV-7) on pneumococcal carriage in children are largely unknown, although highly relevant in the context of subsequent herd effects. OBJECTIVE: To examine the effects of a 2-dose and 2 + 1-dose PCV-7 schedule on nasopharyngeal pneumococcal carriage in young children compared with controls. DESIGN, SETTING, AND PATIENTS: A randomized controlled trial of nasopharyngeal carriage of Streptococcus pneumoniae enrolling 1003 healthy newborns and 1 of their parents in a general community in The Netherlands, with follow-up to age 24 months and conducted between July 7, 2005, and February 14, 2008. INTERVENTION: Infants were randomly assigned to receive 2 doses of PCV-7 at 2 and 4 months; 2 + 1 doses of PCV-7 at 2, 4, and 11 months; or no dosage (control group). MAIN OUTCOME MEASURE: Vaccine serotype pneumococcal carriage rates in infants in the second year of life. RESULTS: At 12 months, vaccine serotype pneumococcal carriage was significantly decreased after both PCV-7 schedules, with vaccine serotype pneumococcal carriage rates of 25% (95% confidence interval [CI], 20%-30%) and 20% (95% CI, 16%-25%) in the 2-dose and 2 + 1-dose schedule groups, respectively, vs 38% (95% CI, 33%-44%) in the control group (both P < .001). At 18 months, in the 2 + 1-dose schedule group, vaccine serotype pneumococcal carriage had further decreased to 16% (95% CI, 12%-20%) and, at 24 months, to 14% (95% CI, 11%-18%; both P < .001); whereas in the 2-dose schedule group, vaccine serotype pneumococcal carriage had remained stable at 18 months (24%; 95% CI, 20%-29%), but at 24 months had further decreased to 15% (95% CI, 11%-19%; both P < .001). In the control group, vaccine serotype pneumococcal carriage remained around 36% to 38% until 24 months. CONCLUSION: Compared with no pneumococcal vaccination, a 2 + 1-dose and 2-dose schedule of PCV-7 resulted in significant reductions of vaccine serotype pneumococcal carriage in the second year of life. TRIAL REGISTRATION: clinicaltrials.gov Identifier: NCT00189020.

Invasive pneumococcal disease among adults: associations among serotypes, disease characteristics, and outcome.

BACKGROUND: The Streptococcus pneumoniae polysaccharide capsule may be related to invasive pneumococcal disease (IPD) course. METHODS: We performed a retrospective cohort study with nationally representative surveillance data from 1075 hospitalized patients with IPD from the Netherlands from 1 June 2004 through 31 May 2006 in the prevaccination era. Serotypes were grouped according to invasive disease potential, rate of the most serious clinical syndromes of meningitis and bacteremia without focus, and case-fatality rates. Multivariable logistic regression analysis was performed to obtain odds ratios adjusted for baseline confounders for the association of serotypes and these outcomes, using the serotypes with the lowest rates as reference. RESULTS: IPD caused by serogroups with low invasive disease potential concerned meningitis or bacteremia without focus in 22% of cases, and 74% of patients had an underlying comorbidity. For highly invasive serogroups these figures were 10% (P < .01) and 56% (P < .01). Individual serotypes varied in the relative rate by which they caused meningitis or bacteremia without focus. Compared with the reference group composed of serotypes 1, 5, 7F, 15B, 20, and 33F, the group of serotypes 3, 19F, 23A, 16F, 6B, 9N, and 18C was associated with increased case-fatality rates (group adjusted odds ratio, 2.6; 95% confidence interval, 1.5-4.7). CONCLUSIONS: The serotype appeared to be independently associated with IPD severity in adults, which indicates that careful monitoring of IPD after implementation of conjugate vaccines is necessary.

Invasive pneumococcal disease in the Netherlands: Syndromes, outcome and potential vaccine benefits.

With a retrospective study of invasive pneumococcal disease (IPD) surveillance data representative for approximately 25% of the Dutch population (1275 hospitalized cases) over the period June 2004-June 2006 prior to the implementation of the 7-valent pneumococcal conjugate vaccine (PCV7), the aim was to provide baseline data on IPD for the interpretation of changes after implementation of conjugate vaccines. The IPD incidence peaked in 3-5-mnth-olds (63 cases per 100,000 persons yearly) and increased in adulthood, particularly after the age of 60yrs, from 26 cases in 60-64-yr-olds to 97 cases per 100,000 in persons > or =90yrs. Beyond the age of 4yrs, 19% of IPD patients were immunocompromised, and this considerable percentage may have implications for vaccine efficacy.