National paediatric immunization program of high risk groups: no effect on the incidence of invasive pneumococcal diseases. Vaccine. 2009;27:3963-3968. [PMID: 19393711 DOI: 10.1016/j.vaccine.2009.04.044]

Serotype distribution of Streptococcus pneumoniae causing invasive disease in children in the post-PCV era: A systematic review and meta-analysis

BACKGROUND

Routine immunisation with pneumococcal conjugate vaccines (PCV7/10/13) has reduced invasive pneumococcal disease (IPD) due to vaccine serotypes significantly. However, an increase in disease due to non-vaccine types, or serotype replacement, has been observed. Serotypes' individual contributions to IPD play a critical role in determining the overall effects of PCVs. This study examines the distribution of pneumococcal serotypes in children to identify leading serotypes associated with IPD post-PCV introduction.

METHODS

A systematic search was performed to identify studies and surveillance reports (published between 2000 and December 2015) of pneumococcal serotypes causing childhood IPD post-PCV introduction. Serotype data were differentiated based on the PCV administered during the study period: PCV7 or higher valent PCVs (PCV10 or PCV13). Meta-analysis was conducted to estimate the proportional contributions of the most frequent serotypes in childhood IPD in each period.

RESULTS

We identified 68 studies reporting serotype data among IPD cases in children. We analysed data from 38 studies (14 countries) where PCV7 was administered and 20 (24 countries) where PCV10 or PCV13 have been introduced. Studies reported early and late periods of PCV7 administration (range: 2001∓13). In these settings, serotype 19A was the most predominant cause of childhood IPD, accounting for 21.8% (95%CI 18.6∓25.6) of cases. In countries that have introduced higher valent PCVs, study periods were largely representative of the transition and early years of PCV10 or PCV13. In these studies, the overall serotype-specific contribution of 19A was lower (14.2% 95%CI 11.1∓18.3). Overall, non-PCV13 serotypes contributed to 42.2% (95%CI 36.1∓49.5%) of childhood IPD cases. However, regional differences were noted (57.8% in North America, 71.9% in Europe, 45.9% in Western Pacific, 28.5% in Latin America, 42.7% in one African country, and 9.2% in one Eastern Mediterranean country). Predominant non-PCV13 serotypes overall were 22F, 12F, 33F, 24F, 15C, 15B, 23B, 10A, and 38 (descending order), but their rank order varied by region.

CONCLUSION

Childhood IPD is associated with a wide number of serotypes. In the early years after introduction of higher valent PCVs, non-PCV13 types caused a considerable proportion of childhood IPD. Serotype data, particularly from resource-limited countries with high burden of IPD, are needed to assess the importance of serotypes in different settings. The geographic diversity of pneumococcal serotypes highlights the importance of continued surveillance to guide vaccine design and recommendations.

Effectiveness of 7-valent pneumococcal conjugate vaccine: A meta-analysis of post-marketing studies

AIM: To investigate the 7-valent pneumococcal conjugate vaccine (PCV7) effectiveness.

METHODS: A systematic literature review of studies which evaluated the effectiveness of PCV7 vaccine was performed searching the keyword “heptavalent pneumococcal conjugate vaccine” in PubMed and Scopus until March 16, 2013. The selection of potential eligible articles was done by two researchers independently on the basis of abstract and title and only post-marketing studies were included in the systematic review. Data extraction was carried out by two researchers with respect to invasive pneumococcal diseases due to both all and vaccine serotypes in pre-vaccine and post-vaccine periods in children less than 5 years. Results of studies which were considered suitable for meta-analysis were combined by means of relative risk (RR) with 95%CI. Vaccine effectiveness was calculated as (1-RR) × 100. Heterogeneity was assessed by I² and a random effects model was used to combine data in the case of heterogeneity. RevMan 5 was used to pool data.

RESULTS: On the whole, 757 eligible papers were identified from the literature search in PubMed and Scopus. Of them, 62 were finally considered in the systematic review and 38 were included in the meta-analysis. In all post-marketing studies included in the systematic review the incidence of invasive pneumococcal diseases due to vaccine serotypes declined significantly with the exception of few studies showing stability or a slight, but not significant, increase. Furthermore most of studies highlighted also a reduction in the incidence of invasive pneumococcal diseases due to all serotypes. With regards to meta-analysis, a random effects model was used to combine data because of the high heterogeneity. Data combination showed that the effectiveness of PCV7 in reducing invasive pneumococcal diseases due to vaccine serotypes and to all serotypes was 84% (95%CI: 74%-90%) and 53% (95%CI: 46%-59%) respectively. These results are confirmatory with respect to the efficacy of PCV7 against invasive pneumococcal diseases due to vaccine serotypes.

CONCLUSION: PCV7 implementation determines a significant decrease of invasive pneumococcal diseases.

The burden of pneumococcal meningitis in Austrian children between 2001 and 2008

The present study was conducted to evaluate the burden of pneumococcal meningitis in Austrian children between 2001 and 2008. Clinical outcome was retrospectively analyzed both on discharge and on follow-up investigations. This study was based on a prospective multicentre surveillance study on hospitalized invasive pneumococcal infections in Austrian children with a total annual "study population" of about 399,000 children aged below 5 years per year. Between 2001 and 2008, 74 cases of pneumococcal meningitis were identified in children aged below 5 years. The mean annual incidence rate for pneumococcal meningitis was 2.3 per 100,000 children in this age group. In 57/74 children (mean age on admission 14.5 ± 13.3 months), outcome data on hospital discharge were available: 5 deaths (8.8%), 20 children (35.1%) with sequelae and 32 children (56.1%) without sequelae were observed. Sequelae on discharge included motor impairment in 8 children (14.0%), hearing impairment in 9 children (15.8%) and/or other complications in 14 children (24.6%). In 7/8 children with motor deficits, matching cerebral lesions were identified by neuroimaging: cerebral infarction in five children, cerebral vasculitis and cerebral abscess in one child each. In 40/57 children, long-term outcome (18.9 ± 20.2 months after discharge) could be assessed: 1 child (2.5%) died 9 months after hospital discharge, 11 children (27.5%) had one or two long-term sequelae and 28 children (70.0%) had no sequelae. Long-term sequelae included motor impairment in three children (7.5%), hearing impairment in nine children (22.5%) and other deficits in two children (5.0%).

CONCLUSION

Our study confirms that pneumococcal meningitis causes high mortality and severe long-term sequelae. On long-term follow-up, we observed improvements of motor impairment, but not of hearing impairment.

Characteristics of invasive pneumococcal disease in hospitalized children in Austria

In a prospective surveillance study covering all pediatric wards in Austria, 308 cases of invasive pneumococcal disease (IPD) were reported in hospitalized children <5 years of age between 2002 and 2012. Incidence was 7.1 per 100,000 per year for IPD with a case fatality rate of 3 %, and 1.9 per 100,000 per year for pneumococcal meningitis with a case fatality rate of 9 %. At hospital discharge, 17 % of the children were not fully recovered and suffered from problems such as hearing or motor deficits. Persistent sequelae 6 months after hospital discharge were present in 13 % of the children, a finding that emphasizes the seriousness of IPD. From 2007 onwards, we observed a shift of pneumococcal serotypes from those covered by the heptavalent vaccine to serotypes consequently added to 10- and 13-valent vaccines, particularly regarding serotype 19A. Among antimicrobial resistances detected, macrolide resistance was predominant; however, between 2002 and 2012, we saw an overall decrease of resistance rates.

CONCLUSION

Considering this change of serotypes and the high rate of permanent sequelae after IPD, our data show the importance of pediatric pneumococcal vaccination and the relevance of continuous monitoring of circulating serotypes. By the end of 2012, which was the first year of universal mass vaccination against pneumococcal disease in Austria, no change in the incidence of invasive pneumococcal disease was observed yet.

Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on vaccine-type invasive pneumococcal disease among young children

BACKGROUND

Pneumococcal conjugate vaccines (PCV) are being implemented globally using a variety of different schedules. The optimal schedule to maximize protection of vaccinated children against vaccine-type invasive pneumococcal disease (VT-IPD) is not known.

METHODS

To assess the relative benefit of various PCV dosing schedules, we conducted a systematic review of studies published in English from 1994 to 2010 (supplemented post hoc with studies from 2011) on PCV effectiveness against VT-IPD among children targeted to receive vaccine. Data on 2-dose and 3-dose primary series, both with and without a booster ("2+0," "2+1," "3+0" and "3+1"), were included. For observational studies using surveillance data or case counts, we calculated percentage reduction in VT-IPD before and after PCV introduction.

RESULTS

Of 4 randomized controlled trials and 31 observational studies reporting VT-IPD among young children, none evaluated a 2+0 complete series, 7 (19%) evaluated 2+1, 4 (11%) 3+0 and 27 (75%) 3+1. Most (86%) studies were from North America or Europe. Only 1 study (observational) directly compared 2 schedules (3+0 vs. 3+1); results supported the use of a booster dose. In clinical trials, vaccine efficacy ranged from 65% to 71% with 3+0 and 83% to 94% with 3+1. Surveillance data and case counts demonstrate reductions in VT-IPD of up to 100% with 2+1 (6 studies) or 3+1 (17 studies) schedules and up to 90% with 3+0 (2 studies). Reductions were observed as early as 1 year after PCV introduction.

CONCLUSIONS

These data support the use of 2+1, 3+0 and 3+1 schedules, although most data of PCV impact on VT-IPD among young children are from high-income countries using 3+1. Differences between schedules for impact on VT-IPD are difficult to discern based on available data.

A review of the impact of pneumococcal polysaccharide conjugate vaccine (7-valent) on pneumococcal meningitis

INTRODUCTION

Streptococcus pneumoniae is the leading cause of bacterial meningitis. Young children, the elderly and those who are immunocompromised or who suffer from chronic diseases have the highest risk of developing pneumococcal meningitis. A 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 in the US and in 2001 in Europe.

METHODS

A literature search was performed in PubMed to identify studies assessing the impact of routine childhood PCV7 vaccination on pneumococcal diseases. Here, we report the impact on pneumococcal meningitis.

RESULTS

A total of 17 articles reporting impact data on pneumococcal meningitis were included in this review: 11 from Western Europe and 6 from North America. In the post-vaccination period, compared with the pre-vaccination period, a reduction ranging from 59.2% in the US, 1 year after vaccine introduction, to 100% in Belgium, 4 years after vaccine introduction in vaccine-type (VT) pneumococcal meningitis incidence was reported in vaccine-eligible children in seven studies. In addition, the majority of studies reported reductions in VT and all-type pneumococcal meningitis incidence in age groups that were not vaccine-eligible.

CONCLUSIONS

The results from this review demonstrate that PCV7 has had a significant impact on pneumococcal meningitis across all ages through its use in pediatric immunization programs. With the introduction of 13-valent PCV (PCV13) we can expect to see a reduction in the incidence of pneumococcal meningitis due to the six additional serotypes included, as well as continued protection against pneumococcal meningitis due to PCV7 serotypes. Robust surveillance systems are essential for the evaluation of the impact of PCV13 on all-type pneumococcal meningitis and for monitoring the evolution of non-vaccine serotype pneumococcal meningitis.

The impact of 7-valent pneumococcal conjugate vaccine on invasive pneumococcal disease: a literature review

INTRODUCTION

Streptococcus pneumoniae can cause invasive pneumococcal diseases (IPD), such as bacteremic pneumonia, bacteremia, meningitis, and sepsis, and non-IPDs, such as otitis media, nonbacteremic pneumonia, and upper respiratory tract infections. It was estimated in 2000 that, worldwide, S. pneumoniae was responsible for 826,000 deaths annually in children aged between 1 month and 5 years. A 7-valent pneumococcal conjugate vaccine (PCV7) was licensed in 2000 in the USA and in 2001 in Europe.

METHODS

A literature search was performed in PubMed to identify studies assessing the impact of routine childhood PCV7 vaccination on pneumococcal morbidity and mortality. Here, the impact on IPD is reported.

RESULTS

A total of 37 articles reporting impact data on IPD were included in this review: four from Australia, 17 from western Europe, and 16 from North America. In vaccine-eligible children in the postvaccination period, a reduction ranging from 39.9% in Spain to 99.1% in the USA in vaccine-type (VT) IPD incidence, compared with the prevaccination period, was reported in 18 studies. All but one of the 30 studies assessing the impact of PCV7 on all-type IPD reported a reduction ranging from 1.7% in Spain to 76.3% in Australia. In addition, the majority of studies reported reductions in VT and all-type IPD incidence in age groups that were not vaccine eligible.

CONCLUSIONS

The results from this review illustrate that PCV7 has had a significant impact on IPD across all ages through its use in pediatric immunization programs. With the introduction of 13-valent pneumococcal conjugate vaccine (PCV13) further reductions in the incidence of IPD due to the six additional serotypes included, as well as continued protection against IPD due to PCV7 serotypes may be expected. Robust surveillance systems are essential for the evaluation of the impact of PCV13 on all-type IPD and for monitoring the evolution of non-VT IPD.

Global prevailing and emerging pediatric pneumococcal serotypes

Streptococcus pneumoniae is the leading cause of vaccine-preventable deaths among children younger than 5 years of age worldwide. The 7-valent pneumococcal conjugate vaccine (PCV7) is currently licensed in more than 90 countries and has contributed to significant declines in the incidence of invasive pneumococcal disease (IPD). Recent studies report an increased incidence of IPD caused by non-PCV7 vaccine serotypes (NVTs). Seroepidemiology of IPD caused by NVTs following the introduction of PCV7 is of interest, and this article provides a comprehensive global summary of the prevailing and emerging serotypes causing IPD in children. Currently, globally emerging or persistent NVTs include serotypes 1, 3, 5, 6A, 7F and 19A. Serotypes included in the recently licensed 10-valent pneumococcal Haemophilus influenzae protein D conjugate vaccine (PCV10) and 13-valent pneumococcal conjugate vaccine (PCV13) account for pneumococcal disease burdens in most developed countries of 65-85% and 80-90%, respectively. The seroprevalence of NVTs after widespread use of PCV10 and PCV13 requires ongoing monitoring.