Theoretic coverage of heptavalent pneumococcal conjugate vaccine in the prevention of community-acquired pneumonia in children in Italy

Bacteremic pneumococcal community-acquired pneumonia in children less than 5 years of age in Italy

BACKGROUND

This study was designed to determine the proportion of bacteremic pneumococcal cases in a group of pediatric subjects with community-acquired pneumonia (CAP), the importance of the different serotypes and the impact of the currently available pneumococcal conjugate vaccines (PCVs).

METHODS

The study involved children who were ≤5 years with radiographically confirmed CAP admitted to hospital in Italy between September 2008 and March 2011. A diagnosis of laboratory-confirmed bacteremic pneumococcal CAP was made in the presence of a culture and/or real-time polymerase chain reaction (PCR) positive for Streptococcus pneumoniae.

RESULTS

A total of 510 children were included in the study. Pneumococcal CAP was diagnosed in 73 cases (14.3%): S. pneumoniae was identified by means of positive real-time PCR in 67 cases (91.8%), a positive blood culture in 1 (1.4%) and both in 5 (6.8%). Complicated pneumonia was observed significantly more often in the pneumococcal-positive cases (P=0.02) and empyema was the main complication (P=0.007). Serotype 19A was most frequently encountered (17 cases; 25.8%), followed by serotypes 14 (10 cases, 15.1%), 4 (5 cases, 7.6%) and 3 (4 cases, 6.1%). The theoretical coverage offered by the available PCVs was calculated to be 31% for PCV7, 37% for PCV10 and 71% for PCV13.

CONCLUSIONS

In Italy, bacteremic pneumococcal CAP accounts for a significant number of CAP cases in children who were ≤5 years, with serotypes 19A and 14 being the most frequent. This suggests that PCV13 is the best means of preventing pneumococcal CAP.

Radiographic pneumonia in young, highly febrile children with leukocytosis before and after universal conjugate pneumococcal vaccination

OBJECTIVES

Studies before the introduction of conjugate pneumococcal vaccine demonstrated a high rate of radiographic pneumonia among highly febrile young children with leukocytosis and no other identified source of infection. We sought to evaluate the impact of universal vaccination with Prevnar (pneumococcal conjugate vaccine [PCV]) on the incidence and characteristics of occult and nonoccult radiographic pneumonia among these children.

METHODS

Retrospective cohort study of children younger than 5 years seen in an urban pediatric emergency department with temperature 39 degrees C or higher, white blood cell count 20,000/microL or higher, and chest radiograph performed. Pneumonia was defined as focal infiltrate or consolidation on chest radiograph as read by an attending radiologist. Occult pneumonia was defined as radiographic pneumonia in the absence of lower respiratory tract signs or cough.

RESULTS

Before universal pneumococcal vaccination, radiographic pneumonia was found in 190 (21%) of 889 (95% confidence interval [CI], 19-24) eligible children compared with 61 (18%) of 335 (95% CI: 14, 23) eligible children after universal vaccination (P = 0.27). Occult pneumonia was identified in 61 (15%) of 404 (95% CI, 12-19) pre-PCV compared with 13 (9%) of 147 (95% CI, 5-15) post-PCV (P = 0.07). In children younger than 2 years, radiographic pneumonia was identified in 121 (17%) of 709 (95% CI, 14-20) pre-PCV and 26 (10%) of 254 (95% CI, 7-15) post-PCV (P = 0.01).

CONCLUSIONS

Clinicians should continue to consider chest radiography in young highly febrile children with leukocytosis and no other identified source of infection.

Impact on respiratory tract infections of heptavalent pneumococcal conjugate vaccine administered at 3, 5 and 11 months of age

Background

Medical and public health importance of pneumococcal infections justifies the implementation of measures capable of reducing their incidence and severity, and explains why the recently marketed heptavalent pneumococcal conjugate vaccine (PCV-7) has been widely studied by pediatricians. This study was designed to evaluate the impact of PCV-7 administered at 3, 5 and 11 months of age on respiratory tract infections in very young children.

Methods

A total of 1,571 healthy infants (910 males) aged 75–105 days (median 82 days) were enrolled in this prospective cohort trial to receive a hexavalent vaccine (DTaP/IPV/HBV/Hib) and PCV-7 (n = 819) or the hexavalent vaccine alone (n = 752) at 3, 5 and 11 months of age. Morbidity was recorded for the 24 months following the second dose by monthly telephone interviews conducted by investigators blinded to the study treatment assignment using standardised questionnaires. During these interviews, the caregivers and the children's pediatricians were questioned about illnesses and the use of antibiotics since the previous telephone call. All of the data were analysed using SAS Windows v.12.

Results

Among the 1,555 subjects (98.9%) who completed the study, analysis of the data by the periods of follow-up demonstrated that radiologically confirmed community-acquired pneumonia (CAP) was significantly less frequent in the PCV-7 group during the follow-up as a whole and during the last period of follow-up. Moreover, there were statistically significant between-group differences in the incidence of acute otitis media (AOM) in each half-year period of follow-up except the first, with significantly lower number of episodes in children receiving PCV-7 than in controls. Furthermore, the antibiotic prescription data showed that the probability of receiving an antibiotic course was significantly lower in the PCV-7 group than in the control group.

Conclusion

Our findings show the effectiveness of the simplified PCV-7 schedule (three doses administered at 3, 5 and 11–12 months of age) in the prevention of CAP and AOM, diseases in which Streptococcus pneumoniae plays a major etiological role. A further benefit is that the use of PCV-7 reduces the number of antibiotic prescriptions. All of these advantages may also be important from an economic point of view.

Pneumococcal serogroups and serotypes in severe pneumococcal pneumonia in Belgian children: theoretical coverage of the 7-valent and 9-valent pneumococcal conjugate vaccines

BACKGROUND

Although the causative pneumococcal serotypes of invasive diseases are already extensively studied, few data are available about the pneumococcal serotypes additionally isolated from broncho-alveolar lavage samples in childhood pneumonia.

STUDY AIM

To identify the causative pneumococcal serotypes in culture proven childhood community acquired pneumonia (CAP) and to calculate the effectiveness of the heptavalent and nonavalent pneumococcal vaccine (7- and 9-valent PnV) in severe pneumococcal pneumonia.

METHODS

All pneumococcal isolates stored from broncho-alveolar lavage, blood culture and pleural fluid in healthy children with CAP were characterized.

RESULTS

Seventy children (median age 2 years 3.5 months) could be included. The most prevalent serotypes were: SGT1 (21.4%), SGT6 (20.0%), SGT19 (12.8%), SGT23 (10.0%), and SGT14 (7.1%). SGT1 was especially prevalent in complicated cases and children >5 years. This first ranking of SGT1 is not reported in invasive pneumococcal disease studies. The overall theoretical coverage of the 7-valent PnV and the 9-valent PnV for pneumococcal pneumonia was 45.7% and 72.8%. The theoretical coverage of both vaccines was equal for non-invasive pneumonia (64%) but the theoretical coverage of the 9-valent PnV for invasive pneumonia was much higher (79% vs. 37.2%). Antibiotic susceptibility to penicillin was 84%, 70% to tetracycline and 61% to erythromycin; however only one strain (MIC = 4 mg/L) was highly resistant to penicillin.

CONCLUSIONS

Based on this serotyping, the theoretical coverage of the 7-valent PnV for proven pneumococcal pneumonia is good but decreases with age. A 9-valent PnV containing SGT1 could significantly increase the coverage, especially for invasive pneumonia. According to these data, penicillin remains the first choice antibiotic treatment for childhood CAP in Belgium.

Cost-effectiveness of universal pneumococcal vaccination for infants in Italy

This study aimed at estimating the health and economic outcomes of universal infant vaccination with seven-valent pneumococcal conjugate vaccine (PCV-7) in Italy. A Markov model simulated lifetime evolution of a birth cohort (538,138 children): universal vaccination would avert 769 invasive infections, 18 deaths and 1323 life years. At base-case analysis, universal three-dose vaccination would cost euro 26,449 (95% CI: 1975-62,075) and euro 38,286 (95% CI: 22,164-70,801) per life year-saved in the societal and the NHS perspective, respectively. In the hypothesis of a 5-year long protection period, vaccination would cost euro 32,694 and euro 43,115 per life-year saved. Considering yearly incidence of invasive pneumococcal disease reported for Veneto and Sardinia regions, PCV-7 vaccination would result highly cost-effective determining a cost of euro 10,479 and euro 16,890 per life year-save in the NHS and the societal perspective, respectively.

Immunogenicity, safety and tolerability of heptavalent pneumococcal conjugate vaccine administered at 3, 5 and 11 months post-natally to pre- and full-term infants

We assessed the immunogenicity, safety and tolerability of heptavalent pneumococcal conjugate vaccine (PCV7) administered three, five and 11 months post-natally to 46 pre-term (PT) and 46 full-term (FT) infants. After each dose, there was no significant difference between the groups in antibody levels for any of the vaccine serotypes. After the second dose, the majority of subjects in both groups showed titres of > or =0.35 microg/mL, whereas an antibody concentration of > or =1.0 microg/mL was usually reached in both PT and FT infants after the third dose. Safety and tolerability was also similar in the groups. These findings support the use of the simplified schedule that includes three doses of PCV7 in both PT and FT infants, and suggest that this may reduce costs, as well as problems related to vaccine supply and administration.

Pneumococcal conjugate vaccines for preventing vaccine-type invasive pneumococcal disease and pneumonia with consolidation on x-ray in children under two years of age

BACKGROUND

Pneumonia, most commonly caused by Streptococcus pneumoniae (Pnc), is a major cause of morbidity and mortality among young children especially in developing countries. Recently, the prevalence of antibiotic-resistant Pnc has increased worldwide such that the effectiveness of preventive strategies, like the new pneumococcal conjugate vaccines (PCV) on rates of invasive pneumococcal disease (IPD) and pneumonia, needs to be evaluated.

OBJECTIVES

To determine the efficacy of PCV in reducing the incidence of IPD due to vaccine serotypes (VT) and x-ray confirmed pneumonia with consolidation of unspecified etiology in children who received PCV before 12 months of age.

SEARCH STRATEGY

We searched the following databases: the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library, Issue 1 2004), MEDLINE (1990 to March 2004) and EMBASE (1990 to December 2003). Reference list of articles, and books of abstracts of relevant symposia, were hand searched. Researchers in the field were also contacted.

SELECTION CRITERIA

Randomised controlled trials (RCTs) comparing PCV with placebo, or another vaccine, among children below two years with IPD and clinical/radiographic pneumonia as outcomes.

DATA COLLECTION AND ANALYSIS

Two reviewers independently identified eligible studies, assessed trial quality, and extracted data. Differences were resolved by discussion. The inverse variance method was used to pool effect sizes.

MAIN RESULTS

We identified four trials assessing the efficacy of PCV in reducing the incidence of IPD, two on x-ray confirmed pneumonia as outcome, and one on clinical pneumonia, with or without x-ray confirmation. Results from pooling HIV-1 negative children from the South African study with the other studies were as follows: the pooled vaccine efficacy (VE) for vaccine-type IPD was 88% (95% confidence interval (CI) 73% to 94%; fixed effect and random effects models), the effect measure was statistically significant (p <0.00001) and there was no heterogeneity (p = 0.77I2 0%); the pooled VE for all-serotype IPD was 66% (95% CI 46% to 79%; fixed effect model), the effect measure was statistically significant (p <0.00001) and there was no statistical heterogeneity (p = 0.09, I2 51%); the pooled VE for x-ray confirmed pneumonia was 22% (95% CI 11% to 31%; both fixed effect and random effects models) and there was no statistical heterogeneity (p = 0.80, I2 0%). Analyses that included all the children in the South African study (HIV-1 negative and HIV-1 positive children) and pooled with data from the other studies gave very similar results.

REVIEWERS' CONCLUSIONS

PCV is effective in reducing the incidence of IPD from all serotypes but exerts a greater effect in reducing VT IPD. Although PCV is also effective in reducing the incidence of x-ray confirmed pneumonia, there are still uncertainties about the definition of this outcome. Additional randomised controlled trials are currently in progress.