Pediatric Infectious Disease Journal:
Systematic Review of the Effect of Pneumococcal Conjugate Vaccine Dosing Schedules on Vaccine-type Invasive Pneumococcal Disease Among Young Children
Conklin, Laura MD*; Loo, Jennifer D. MPH*; Kirk, Jennifer MSc†; Fleming-Dutra, Katherine E. MD*‡; Deloria Knoll, Maria PhD§; Park, Daniel E. MSPH§; Goldblatt, David MBChB, PhD¶; O’Brien, Katherine L. MD, MPH§; Whitney, Cynthia G. MD, MPH*
From the *Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, Atlanta, GA; †Westat Inc., Rockville, MD; ‡Epidemic Intelligence Service, Centers for Disease Control and Prevention, Atlanta, GA; §International Vaccine Access Center, Johns Hopkins Bloomberg School of Public Health, Baltimore, MD; and ¶Institute for Child Health, University College London, London, United Kingdom.
Accepted for publication August 13, 2013.
Support for this project was provided by Program for Appropriate Technology in Health (PATH) through funding from the GAVI Alliance. The views expressed by the authors do not necessarily reflect the views of CDC, GAVI, PATH or IVAC. M.D.K. has received support from Novartis for participation on a Data and Safety Monitoring Board and meeting travel reimbursement from Pfizer. D.G.’s laboratory performs contract and or collaborative research for/with Pfizer, GlaxoSmithKline, Merck, Novartis and Sanofi Pasteur. D.G. has received travel or honorarium support for participation in external expert committees for Merck, Sanofi Pasteur, Pfizer and GlaxoSmithKline. K.O.B. received grant support from Pfizer, GlaxoSmithKline and has received travel or honorarium support for participation in external expert committees for Merck, Aventis-pasteur and GlaxoSmithKline. The authors have no other funding or conflicts of interest to declare.
Address for correspondence: Laura Conklin, MD, Respiratory Diseases Branch, Division of Bacterial Diseases, National Center for Immunizations and Respiratory Diseases, Centers for Disease Control and Prevention, 1600 Clifton Road, NE, Mailstop A-04, Atlanta, GA 30333. E-mail: LConklin@cdc.gov.
This is an open-access article distributed under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives 3.0 License, where it is permissible to download and share the work provided it is properly cited. The work cannot be changed in any way or used commercially.
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.
Streptococcus pneumoniae can cause a variety of clinical syndromes among both children and adults. When infection spreads to a normally sterile site, such as the brain or blood, the resulting syndrome, called invasive pneumococcal disease (IPD), is associated with significant morbidity and mortality. The burden of IPD falls disproportionately on young children, especially those in low-income countries, and persons at high risk of infection because of underlying medical conditions such as HIV or sickle cell disease.1,2 A limited number of pneumococcal serotypes cause the majority of IPD in both high- and low-risk groups; 7 of these serotypes are included in the 7-valent pneumococcal conjugate vaccine (PCV7), first licensed in February 2000.3 Within 6 years of PCV7 introduction in the United States, use of a 3-dose primary series with a booster in the second year of life (a “3+1” schedule) and a national catch-up campaign among those under 5 years of age nearly eliminated vaccine-type IPD (VT-IPD) among children targeted to receive the vaccine.4 More recently, licensed PCV formulations that include 10 and 13 serotypes (PCV10 and PCV13, respectively) hold promise to further reduce the burden of pneumococcal disease.
Between 2000 and 2008, PCV7 was introduced into the national immunization programs of 26 countries, including 1 middle-income country.5 As of December 2011, 77 countries offered PCV universally or had >50% coverage with the vaccine; 30 used a 3+1 schedule and 47 used a reduced dose schedule of either 3 primary doses without a booster (3+0) or 2 primary doses with a booster (2+1) (Sources: Database maintained by WHO, supplemented with data from VIMS [Vaccine Information Management System of IVAC] and individual country reports or press releases). Although immuno genicity data support the use of reduced dose schedules for most vaccine serotypes, whether reduced dose schedules can provide equivalent protection against VT-IPD to a 3+1 schedule when introduced into a national immunization program is unclear.6 The World Health Organization currently recommends that countries introduce PCV as part of the Expanded Programme on Immunisation schedule, yet specific guidance on the relative effectiveness of different PCV dosing schedules in various settings is lacking.7 Public health leaders newly considering PCV introduction, as well as those with established programs, face challenging decisions regarding the most appropriate dosing schedule for their populations, including the benefits of a 3-dose primary series compared with a 2-dose primary series, the benefits of a booster dose and whether a 3-dose series should be administered on a 2+1 or a 3+0 schedule. In this report, we attempt to provide insight into the relative benefits of different dosing schedules by presenting findings from a systematic review of the available literature on PCV dosing effects on VT-IPD among young children.
MATERIALS AND METHODS
This analysis is part of a larger project describing the impact of PCV dosing schedules on IPD, immunogenicity, nasopharyngeal carriage, pneumonia and indirect effects. Details on the literature search terms and methods used in this systematic review are described elsewhere (see Methods Appendix8). In brief, a systematic literature review was performed to collect all available English language data published from January 1994 to September 2010 (supplemented post hoc with studies from 2011) on the effect of various PCV vaccination schedules among immunized children on immunogenicity, nasopharyngeal colonization, IPD, pneumonia and on indirect effects among unvaccinated populations. Articles published in 14 databases, from ad hoc unpublished sources and abstracts from meetings of the International Symposium on Pneumococci and Pneumococcal Disease (1998–2010) and the Interscience Conference on Antimicrobial Agents and Chemotherapeutics (1994–2010), were searched. We included all randomized controlled trials (RCTs), nonrandomized trials, surveillance database analyses and observational studies of any PCV schedule on 1 or more outcomes of interest. Studies were included for abstraction if 23-valent pneumococcal polysaccharide vaccine (PPV23) was used as a booster dose, but not as a primary dose. Titles and abstracts were reviewed twice and those with relevant content on 1 of 5 outcomes (immunogenicity, carriage, invasive disease, pneumonia and indirect effects) underwent full review using a standardized data collection instrument. We did not search non-English language literature because of the low likelihood they would have relevant data for this project. Details on the search methods are provided in the Methods Appendix.8
Citations Included i...Image Tools
Citations recovered through the literature search went through several stages of independent review to determine their eligibility, as described elsewhere.8 Citations meeting inclusion criteria were categorized on an outcome specific basis into “study families,” where each family included abstracts or publications generated from a single protocol, population, surveillance system or other data collection system relevant to that outcome. Investigators identified primary data from the individual studies making up each study family for inclusion in the analysis. The primary data were selected as the most current and complete data available for that study family. In some cases, these data were drawn from more than 1 publication within a family. We also defined “study arms” as a group of children distinguished by immunization schedule or PCV product.
We abstracted core information on the following: number of children in a “study arm”; PCV manufacturer, valency and conjugate protein; coadministered vaccines; country; age at each dose and date of study and publication. Additional data for the IPD outcome included rates of vaccine serotype IPD (per 100,000 population), absolute case counts of VT-IPD and reported percentage reduction in VT-IPD after PCV introduction. Data on both VT-IPD and VT pneumococcal bacteremia were considered duplicative, in which case only VT-IPD was included. We included both VT-meningitis and VT-IPD within a single study family to allow characterization of the meningitis outcome independently of VT-IPD.
Inclusion and Exclusion Criteria
We included all data published from RCTs, nonrandomized trials, case-control studies, indirect cohort studies, surveillance database analyses (population-based data) and case series (sentinel site data) using any PCV schedule if the citation or abstract reported data on VT pneumococcal meningitis, VT pneumococcal bacteremia or all VT-IPD. To describe the direct impact of the vaccine among young children, we only included studies that reported data on children targeted to receive vaccine; for surveillance analyses and case series, this meant limiting studies to those that reported impact of vaccine among children ≤2 years of age. For controlled trials, case-control studies and indirect cohort studies, data on children ≤5 years of age were also included as long as they were eligible to receive vaccine. We excluded studies that reported pneumococcal bacteremia only in the setting of clinical pneumonia as well as those that reported IPD only among older age groups; these data are included in the articles on pneumonia and indirect effects, respectively, found in this supplement.9,10 We also excluded review articles, those that only provided data for single serotypes and those that only reported data from either before or after PCV introduction but not from both periods.
Pneumococcal Vaccine Dosing Schedules
We defined a primary series as either 2 or 3 doses received before 7 months of age. A booster dose was defined as a dose of PCV or PPV23 received after 9 months of age and after the completion of a primary series. A complete series was defined as the primary series alone for settings where no booster was planned, or the primary series plus the booster dose for settings where this was part of the planned schedule; specifically, these include a 2-dose primary series with or without a booster of PCV or PPV23 (2+1, 2+0) or a 3-dose primary series with or without a booster of PCV or PPV23 (3+1, 3+0).
The studies identified in this systematic review represent heterogeneous designs. Even when clinical methods were similar between studies, the analyses presented were often very different. We attempted to identify studies that would allow comparison between schedules either by (1) directly comparing PCV schedules within the same study, (2) including schedule-specific data compared with no vaccine within the same study or (3) including schedule-specific data that could be compared between studies using similar methodology (eg, among indirect cohort studies). Data were first summarized in descriptive analyses to provide an overview of the amount and variability of the data by schedule and study method.
For RCT, vaccine efficacy was used as the measure of impact. For surveillance database analyses and case series reporting VT-IPD over a given period, we calculated percentage reduction by defining baseline incidence as the mean of all data points reported before PCV introduction. When annual data on postintroduction incidence were available, we calculated percentage reduction from baseline using the data point given for each year reported. If annual data were not available, we used the percentage reduction reported in the study for the specified period. In cases where only the average postintroduction incidence rate over a period was provided, we calculated percentage reduction from baseline to the reported rate and assigned it to the median year of the date range provided. When possible, incidence rates during the year of introduction were excluded from these calculations. To compare the impact of vaccine in early with late phases postintroduction, we grouped data into ≤3 years after PCV introduction and >3 years after introduction. When information on PCV dosing schedules within national immunization programs was not reported, we obtained it through data reported by World Health Organization (http://apps.who.int/immunization_monitoring/en/globalsummary/countryprofileselect.cfm) or the Vaccine Information Management System (http://www.jhsph.edu/ivac/vims).
Statistical significance was defined as P < 0.05; SAS version 9.2 (SAS Institute Inc., Cary, NC) was used for all analyses.
Of 12,980 citations reviewed, we identified 99 study families that included data on PCV and pneumococcal meningitis, bacteremia or all-IPD (Fig. 1). Of these, 35 study families (from 36 reports) included data on young children receiving PCV, 33 (94%) reported data on only VT-IPD, 2 (6%) reported on VT-meningitis and VT-IPD, 1 (3%) reported on VT-bacteremia and VT-meningitis and 1 (3%) reported only on VT-bacteremia (Appendix). The types of studies reporting these data included 4 clinical RCTs and 31 observational studies.
Most studies (n = 26; 74%) were published after 2007 and most were conducted in North America and Europe (n = 30; 86%), although studies from Africa (n = 2) and Oceania (n = 3) were also represented (Table 1). A 3+1 or 3+PPV23 schedule (n = 27; 75%) was more commonly evaluated than either 2+1 (n = 7; 19.4%) or 3+0 (n = 4; 11.1%). No studies evaluated routine use of a 2+0 schedule, although 5 (13.9%) observational studies looked at the effectiveness of a 2-dose primary series (ie, an incomplete series) in the setting of countries routinely using 2+1 or 3+1. Three studies, all of which were conducted in Australia, used PPV23 as a booster dose. All but 2 studies evaluated PCV7; these 2 evaluated a 9-valent vaccine (PCV9). None of the studies evaluated PCV10 or PCV13.
Randomized Controlled Trials
We identified 4 double-blind RCTs in 3 different countries; the studies evaluated vaccine efficacy against VT-IPD among young children for either a 3+0 or 3+1 schedule compared with no PCV (Table 2). No RCTs with VT-IPD outcomes directly compared dosing schedules or evaluated a 2+0 or 2+1 schedule. Two of the RCTs—1 in The Gambia and the other in South Africa—used PCV9 in a 3+0 schedule setting and 2 used PCV7 in a 3+1 schedule setting in the United States.11–14 In The Gambia, investigators compared 8189 vaccinated children to 8151 placebo controls and estimated efficacy against VT-IPD to be 71% in their intent-to-treat (ITT) analysis.13 A similar ITT vaccine efficacy (83%) was demonstrated in the South Africa trial involving over 39,000 children12; the vaccine was slightly less efficacious (65%) among children infected with HIV. The 2 studies conducted in the United States both reported high ITT vaccine efficacy, 1 (VE 94%) was conducted in the general US population11 and the other (VE 83%) was conducted among American Indian children, a population known to be at high risk for IPD.14
Case-Control and Indirect Cohort Studies
We identified 3 case-control studies and 3 indirect cohort studies that allowed for comparisons of different PCV schedules (Table 3). These studies were conducted in 4 different countries routinely using either 2+1 or 3+1 schedules and estimated vaccine effectiveness of various PCV schedules compared with no PCV in either a 2+1 or a 3+1 vaccine setting.16–19 Despite varying study methods and settings, all studies used PCV7 and all showed significant effectiveness against VT-IPD among children targeted to receive vaccine. Across studies, point estimates of vaccine effectiveness among partially vaccinated children who had received 2 primary doses without a booster (2+0) ranged from 70% to 99%, 2+1 ranged from 98% to 100%, 3+0 ranged from 77% to 98% and 3+1 ranged from 81% to 100%. One case-control study, conducted in the United States, also directly analyzed the risk of VT-IPD between schedules.17 In this analysis, a 3+1 schedule provided more protection against VT-IPD than a 3+0 schedule (odds ratio = 0, 95% CI: 0–0.87); other direct comparisons were not significant but the number of children vaccinated on either 2+1 or 2+0 schedule was relatively small.
Observational Surveillance Studies or Case Series Studies
We identified 25 surveillance or case series study families (26 citations) conducted in 12 countries that described the impact of national PCV introduction on any VT-IPD among young children (Table 4). Of these, 23 (92%) reported data on VT-IPD of any syndrome, 2 (8%) on VT-bacteremia without focus and 3 (12%) on VT-meningitis. Although surveillance methods varied and each study only reported the impact of 1 particular PCV dosing schedule, some general comparisons between schedules can be made across this group of reports. One similarity observed among nearly all studies was a significant impact of PCV introduction on VT-IPD over time in populations routinely using 2+1, 3+0 and 3+1 schedules; no data were available for a 2+0 schedule since no country routinely uses this schedule (Fig. 2). Reductions were also observed in the 4 studies conducted in indigenous populations: 2 conducted in Australia using 3+PPV23 and 2 conducted in the United States using a 3+1 schedule. Percentage reduction in VT-IPD ranged from 11% to 100% across studies, populations and time from vaccine introduction. A single study, conducted in Austria, reported an increase in VT-IPD (50% increase) and a 4% decrease in VT-meningitis 2 years after PCV7 introduction although the number of cases was small and coverage was only 25%.22 In general, more pronounced reductions were seen >3 years compared with ≤3 years post PCV introduction (Fig. 3A, B). Studies reporting percentage change in both pneumococcal bacteremia and meningitis all took place in countries using a 3+1 schedule and all demonstrated reductions in VT disease.
Our systematic review of the effect of different PCV dosing schedules on VT-IPD among young children demonstrates the effectiveness of PCV against VT-IPD (of all syndromes), VT-bacteremia and VT-meningitis, across diverse study methods, populations and dosing schedules. The study designs captured by this approach are highly varied and complement recent summary measures (ie, meta-analyses) which are limited to small numbers of studies of comparable designs.6 In this way, our findings allow for a broader assessment of disease impact across different groups and time.
PCV7 was initially licensed with a 4-dose (3+1) schedule46 and, not surprisingly, the vast majority of data on the impact of PCV on VT-IPD among young children identified in this review originate from established programs using 3+1 schedules. These studies showed that a 3+1 schedule reduced VT-IPD in a variety of settings and populations. Using schedules with fewer than 4 doses is of increasing interest to policy makers introducing PCV who aim to optimally reduce disease in both vaccinated children and unvaccinated contacts, but who also are working with limited budgets and crowded immunization schedules. No RCTs or observational studies included in this review evaluated the effects of a 2+0 schedule setting on VT-IPD; however, both 2+1 and 3+0 schedule settings have demonstrated impact in a variety of epidemiological contexts. A 3+0 PCV schedule has proven efficacy in 2 RCTs conducted in low-income settings12,13 and demonstrated impact against VT-IPD among the general population of young children in Australia in 2 surveillance studies.29,30 Effectiveness of a 2+1 dosing schedule has been shown effective against VT-IPD among partially vaccinated children in the United States where a 3+1 schedule is routinely used, and disease reductions were seen in several European countries and Quebec, Canada, where the national immunization program implemented a 2+1 schedule with a catch-up campaign. Since completion of our literature search, a cluster-randomized, double-blind clinical trial was published that directly compared a 2+1 schedule to a 3+1 schedule using a 10-valent protein D PCV (PCV10) in Finland.15 In this study, vaccine effectiveness was 92% (95% CI: 58–100) with 2+1 doses and 100% (95% CI: 83–100%) with 3+1 doses, which is similar to estimates observed in clinical trials using 3+1 or 3+0 schedules in the United States, South Africa and The Gambia.11–14 Additional population-based data emerging from South Africa, a country with high HIV prevalence, has demonstrated a significant reduction in VT-IPD among children <5 years old only 2 years following PCV introduction using a 2+1 schedule of PCV7 without catch-up.47
While differences in effectiveness may exist between 2+1 and 3+0 schedules, we found no studies that directly compared IPD outcomes from these schedules to each other. The 2 case-control studies that evaluated the effectiveness of both 2+1 and 3+0 doses of PCV, compared with no vaccine, were conducted in countries using 2+1 and 3+1 schedules with catch-up vaccination.17,20 Both studies showed significant and similar reductions in VT-IPD among young children with either dosing schedule. Differences in impact between reduced dose schedules may be more significant in settings where PCV coverage is low and herd effects are not strong enough to allow for protection of unvaccinated individuals and high-risk groups. In addition, the sustainability of protection using reduced dose schedules has not yet been fully documented. Here, we observe reductions in VT-IPD using 3+1 and 3+PPV23 schedules up to 6 years after PCV introduction in the United States and Australia; however, further evaluation of 2+1 and 3+0 schedules is needed to determine whether they provide similar long-term protection.
One factor that may play a major role in differentiating between various reduced dose schedules is whether a booster dose confers added protection compared with a schedule without a booster dose. While this theory is supported by immunological and carriage data,48,49 our search identified only 1 study that directly compared schedules to evaluate the benefit of a booster dose on VT-IPD outcomes.17 This study found that a booster confers slightly higher protection against VT-IPD; however, other case-control and indirect cohort studies that compared various PCV dosing schedules against no vaccine all found similar point estimates of effectiveness for schedules with or without a booster.16,18–21 All of these studies were conducted among the general population of young children. The 1 study that specifically evaluated the efficacy of PCV among HIV-infected children (an RCT in South Africa) suggested that a 3+0 schedule does not incur the same level of protection as in HIV-uninfected children.12 In the absence of data to determine whether a PCV booster dose may benefit such high-risk populations, lessons may be learned from other protein-conjugate vaccines used in low-income settings with high HIV prevalence. In recent years, data from South Africa have demonstrated a small increase in invasive Haemophilus influenzae type b (Hib) incidence using a 3+0 schedule for Hib vaccine administered at 6, 10 and 14 weeks of age.50 A similar but more marked phenomenon was observed in the United Kingdom using a 3+0 schedule for Hib at 2, 3 and 4 months of age.51 In both countries, resurgence of Hib disease was controlled by the implementation of a booster dose. Although this phenomenon does not appear to be a common experience among other countries using Hib without a booster dose, there are few countries with sufficiently robust surveillance systems to identify such a resurgence should it occur. Whether lack of a PCV booster could result in a resurgence of VT-IPD disease in areas with high HIV prevalence or other risk factors for disease has yet to be seen.
Another important consideration for policy makers contemplating reduced dose schedules is whether a difference may exist between a 2-dose and 3-dose primary series. Minimal data exist on the benefits of a 2-dose primary series, and no studies directly compare 2 doses to 3 doses. The studies that have reported on IPD impact of a 2-dose primary series were all for partially vaccinated children in the setting of a national schedule using either 3 or 4 total doses.16,17,19,20,52 Still, the ability for either 2 or 3 primary doses to provide some protection against VT-IPD is supported in the literature through several key studies. Three case-control and 3 indirect cohort studies in 4 different countries demonstrated a reduction in VT-IPD among young children who received either 2 or 3 primary doses compared with no vaccine.16–20,52 Differences between the primary series were not discernible in these studies. Although not included in this systematic review, a difference between primary series was suggested in a descriptive report using IPD surveillance data over a period of 27 months from the Unites States. In this study, a greater number of invasive 6B breakthrough cases were seen among children who had received a 2-dose primary series compared with 3 doses.53 This study was conducted in a country using a 3+1 schedule early after vaccine introduction and during a period of vaccine shortage, so therefore may not represent a true difference between a 2-dose primary series when compared with 3-dose primary series, especially for an established program; nevertheless its findings are consistent with immunological and carriage data that suggest a 3-dose primary series may provide better protection than 2 primary doses for some vaccine serotypes, in particular serotype 6B.54–57 Ultimately, however, the number and schedule of doses to include in a primary series may depend on the setting. Using 3 doses in the primary series may be preferable to 2 doses to optimize protection of infants in the first year of life or where attaining high coverage for routine vaccinations given late in the first year of life or in the second year (ie, given with measles vaccine) is challenging or uncertain. In mature PCV programs (where VT carriage rates are low), the risk of disease experienced by children in the period before a booster dose may be sufficiently reduced such that the third priming dose is not a key element of a disease prevention strategy.
The studies captured by this review contribute to other systematic meta-analyses guiding policy decisions regarding PCV vaccine introduction.6,58,59 While these reviews also suggest that 3-dose schedules may provide significant protection against VT-IPD in young children in high-income countries with established national immunization programs, the benefits of using different schedules may ultimately depend on the setting in which they are implemented. A 3-dose primary schedule may provide better protection in the first year of life when children are at highest risk of disease; however, a schedule with a booster dose (eg, 2+1) may provide enhanced long-term protection, in particular for serotype 1.60 Our findings support decisions made by the Pan American Health Organization and World Health Organization to recommend 3-dose schedules (either 3+0 or 2+1) in countries with established programs, and the use of a 3-dose primary series in settings where vaccination coverage in the second year of life is low.61,62 More studies are needed to fully evaluate expanded serotype PCV products (PCV10 and PCV13) and to assess whether 2+1, 3+0 and 3+1 schedules provide equal protection against pneumococcal serotypes that particularly affect children in the second year of life, especially in low-income countries and countries with a high burden of HIV.
The authors gratefully acknowledge the tremendous support from the following: Becky Roberts, Karrie-Ann Toews and Carolyn Wright from the Centers for Disease Control and Prevention, Respiratory Diseases Branch; Catherine Bozio, Rose Chang, Jamie Felzer, Amy Fothergill, Sara Gelb, Kristen Hake, Sydney Hubbard, Grace Hunte and Shuling Liu from Emory University Rollins School of Public Health and Bethany Baer, Subash Chandir, Stephanie Davis, Sylvia Kauffman, Min Joo Kwak, Paulami Naik and Meena Ramakrishnan from The Johns Hopkins Bloomberg School of Public Health.
1. van Hoek AJ, Andrews N, Waight PA, et al. The effect of underlying clinical conditions on the risk of developing invasive pneumococcal disease in England. J Infect. 2012;65:17–24
2. Battersby AJ, Knox-Macaulay HH, Carrol ED. Susceptibility to invasive bacterial infections in children with sickle cell disease. Pediatr Blood Cancer. 2010;55:401–406
3. Johnson HL, Deloria-Knoll M, Levine OS, et al. Systematic evaluation of serotypes causing invasive pneumococcal disease among children under five: the pneumococcal global serotype project. PLoS Med. 2010;7:e1000348
4. Pilishvili T, Lexau C, Farley MM, et al.Active Bacterial Core Surveillance/Emerging Infections Program Network. Sustained reductions in invasive pneumococcal disease in the era of conjugate vaccine. J Infect Dis. 2010;201:32–41
5. Centers for Disease Control and Prevention. . Progress in introduction of pneumococcal conjugate vaccine—worldwide, 2000–2008. Morb Mortal Wkly Rep. 2008;57:1148–1151
6. Scott P, Rutjes AW, Bermetz L, et al. Comparing pneumococcal conjugate vaccine schedules based on 3 and 2 primary doses: systematic review and meta-analysis. Vaccine. 2011;29:9711–9721
7. SAGE Pneumococcal Conjugate Vaccine Working Group. . Detailed Review Paper on Pneumococcal Conjugate Vaccine—presented to the WHO Strategic Advisory Group of Experts (SAGE) on Immunization. November 2006
8. Loo JD, Conklin L, Deloria Knoll M, et al. Methods for a systematic review of pneumococcal conjugate vaccine dosing schedules. Pediatr Infect Dis J. 2014;;33 (Suppl 2)::S182–S187
9. Loo JD, Conklin L, Fleming-Dutra KE,, et al. Systematic review of the effect of pneumo coccal conjugate vaccine dosing schedules on prevention of pneumonia. Pediatr Infect Dis J. 2014;;33 (Suppl 2)::S140–S151
10. Loo JD, Conklin L, Fleming-Dutra KE,, et al. Systematic review of the indirect effect of pneumococcal conjugate vaccine dosing schedules on pneumococcal disease and colonization. Pediatr Infect Dis J. 2014;;33 (Suppl 2)::S161–S171
11. Black S, Shinefield H, Fireman B, et al. Efficacy, safety and immunogenicity of heptavalent pneumococcal conjugate vaccine in children. Northern California Kaiser Permanente Vaccine Study Center Group. Pediatr Infect Dis J. 2000;19:187–195
12. Klugman KP, Madhi SA, Huebner RE, et al.Vaccine Trialists Group. A trial of a 9-valent pneumococcal conjugate vaccine in children with and those without HIV infection. N Engl J Med. 2003;349:1341–1348
13. Cutts FT, Zaman SM, Enwere G, et al.Gambian Pneumococcal Vaccine Trial Group. Efficacy of nine-valent pneumococcal conjugate vaccine against pneumonia and invasive pneumococcal disease in The Gambia: randomised, double-blind, placebo-controlled trial. Lancet. 2005;365:1139–1146
14. O’Brien KL, Moulton LH, Reid R, et al. Efficacy and safety of seven-valent conjugate pneumococcal vaccine in American Indian children: group randomised trial. Lancet. 2003;362:355–361
15. Palmu AA, Jokinen J, Borys D, et al. Effectiveness of the ten-valent pneumococcal Haemophilus influenzae
protein D conjugate vaccine (PHiD-CV10) against invasive pneumococcal disease: a cluster randomised trial. Lancet. 2013;381:214–222
16. Mahon BE, Hsu K, Karumuri S, et al.U.S. Pediatric Multicenter Pneumococcal Surveillance Group; Massachusetts Department of Public Health Epidemiologists. Effectiveness of abbreviated and delayed 7-valent pneumococcal conjugate vaccine dosing regimens. Vaccine. 2006;24:2514–2520
17. Whitney CG, Pilishvili T, Farley MM, et al. Effectiveness of seven-valent pneumococcal conjugate vaccine against invasive pneumococcal disease: a matched case-control study. Lancet. 2006;368:1495–1502
18. Barricarte A, Castilla J, Gil-Setas A, et al. Effectiveness of the 7-valent pneumococcal conjugate vaccine: a population-based case-control study. Clin Infect Dis. 2007;44:1436–1441
19. de Serres G. Using the indirect cohort method to measure effectiveness of pneumococcal conjugate vaccine over a 7-year period. 6th International Symposium on Pneumococci and Pneumococcal Disease. June 8–12, 2008 Reykjavik, Iceland. Abstract 368
20. Deceuninck G, De Wals P, Boulianne N, et al. Effectiveness of pneumococcal conjugate vaccine using a 2+1 infant schedule in Quebec, Canada. Pediatr Infect Dis J. 2010;29:546–549
21. Rückinger S, van der Linden M, Reinert RR, et al. Reduction in the incidence of invasive pneumococcal disease after general vaccination with 7-valent pneumococcal conjugate vaccine in Germany. Vaccine. 2009;27:4136–4141
22. Rendi-Wagner P, Paulke-Korinek M, Kundi M, et al. National paediatric immunization program of high risk groups: no effect on the incidence of invasive pneumococcal diseases. Vaccine. 2009;27:3963–3968
23. Foster D, Walker AS, Griffiths D, et al. Invasive pneumococcal disease—initial impact of the conjugate vaccine in the Oxfordshire region of the UK. 6th International Symposium on Pneumococci and Pneumococcal Disease. June 8–12, 2008 Reykjavik, Iceland Abstract 357
24. Vestrheim DF, Løvoll O, Aaberge IS, et al. Effectiveness of a 2+1 dose schedule pneumococcal conjugate vaccination programme on invasive pneumococcal disease among children in Norway. Vaccine. 2008;26:3277–3281
25. De Wals P, Jette L, Sevin E, et al. Changes in the Epidemiology of Invasive Pneumococcal Disease (ipd) Following Implementation of a 7-Valent Pneumococcal Conjugate Vaccine (pcv7) Program in Quebec, Canada. Abstr Intersci Conf Antimicrob Agents Chemother.. 2008;48:365
26. Harboe ZB, Valentiner-Branth P, Benfield TL, et al. Effectiveness of heptavalent pneumococcal conjugate vaccination on invasive pneumococcal disease one year after the introduction in the Danish childhood vaccination programme. Clin Microbiol Infect. 2009;15:S303–S304 -
27. Miller E, Andrews NJ, Waight PA, et al. Herd immunity and serotype replacement 4 years after seven-valent pneumococcal conjugate vaccination in England and Wales: an observational cohort study. Lancet Infect Dis. 2011;11:760–768
28. Hanquet G, Lernout T, Vergison A, et al.Belgian IPD Scientific Committee. Impact of conjugate 7-valent vaccination in Belgium: addressing methodological challenges. Vaccine. 2011;29:2856–2864
29. Roche PW, Krause V, Cook H, et al.Enhanced Invasive Pneumococcal Disease Surveillance Working Group; Pneumococcal Working Party of the Communicable Diseases Network Australia. Invasive pneumococcal disease in Australia, 2006. Commun Dis Intell Q Rep. 2008;32:18–30
30. Lehmann D, Willis J, Moore HC, et al. The changing epidemiology of invasive pneumococcal disease in aboriginal and non-aboriginal western Australians from 1997 through 2007 and emergence of nonvaccine serotypes. Clin Infect Dis. 2010;50:1477–1486
31. Krause VL, Cook H, Selvey CE. Impact of 7vPCV and 23vPPV booster on eligible children in the Northern Territory of Australia: impressive, but not the total answer. 5th International Symposium on Pneumococci and Pneumococcal Diseases; April 2–6, 2006 Alice Springs, Australia Abstract 55
32. Black SB, Shinefield HR, Hansen J, et al. Postlicensure evaluation of the effectiveness of seven valent pneumococcal conjugate vaccine. Pediatr Infect Dis J. 2001;20:1105–1107
33. Black S, Shinefield H, Baxter R, et al. Impact of the use of heptavalent pneumococcal conjugate vaccine on disease epidemiology in children and adults. Vaccine. 2006;24(Suppl 2):S79–S80
34. Kellner JD, Vanderkooi OG, MacDonald J, et al. Changing epidemiology of invasive pneumococcal disease in Canada, 1998-2007: update from the Calgary-area Streptococcus pneumoniae
research (CASPER) study. Clin Infect Dis. 2009;49:205–212
35. Reingold A, Hadler J, Farley MM, et al. Invasive pneumococcal disease in children 5 years after conjugate vaccine introduction—eight States, 1998–2005. Morb Mort Wkly Rep. 2008;57:144–148
36. Singleton RJ, Hennessy TW, Bulkow LR, et al. Invasive pneumococcal disease caused by nonvaccine serotypes among alaska native children with high levels of 7-valent pneumococcal conjugate vaccine coverage. JAMA. 2007;297:1784–1792
37. Tyrrell GJ, Lovgren M, Chui N, et al. Serotypes and antimicrobial susceptibilities of invasive Streptococcus pneumoniae
pre- and post-seven valent pneumococcal conjugate vaccine introduction in Alberta, Canada, 2000–2006. Vaccine. 2009;27:3553–3560
38. Muñoz-Almagro C, Jordan I, Gene A, et al. Emergence of invasive pneumococcal disease caused by nonvaccine serotypes in the era of 7-valent conjugate vaccine. Clin Infect Dis. 2008;46:174–182
39. Kaplan SL, Mason EO Jr, Wald ER, et al. Decrease of invasive pneumococcal infections in children among 8 children’s hospitals in the United States after the introduction of the 7-valent pneumococcal conjugate vaccine. Pediatrics. 2004;113(3 pt 1):443–449
40. Aristegui J, Bernaola E, Pocheville I, et al. Reduction in pediatric invasive pneumococcal disease in the Basque Country and Navarre, Spain, after introduction of the heptavalent pneumococcal conjugate vaccine. Eur J Clin Microbiol Infect Dis. 2007;26:303–310
41. Rodenburg GD, de Greeff SC, Jansen AG, et al. Effects of pneumococcal conjugate vaccine 2 years after its introduction, the Netherlands. Emerg Infect Dis. 2010;16:816–823
42. Winters M, Patrick DM, Marra F, et al. Epidemiology of invasive pneumococcal disease in BC during the introduction of conjugated pneumococcal vaccine. Can J Public Health. 2008;99:57–61
43. Weatherholtz R, Millar EV, Moulton LH, et al. Invasive pneumococcal disease a decade after pneumococcal conjugate vaccine use in an American Indian population at high risk for disease. Clin Infect Dis. 2010;50:1238–1246
44. Benito-Fernández J, Raso SM, Pocheville-Gurutzeta I, et al. Pneumococcal bacteremia among infants with fever without known source before and after introduction of pneumococcal conjugate vaccine in the Basque Country of Spain. Pediatr Infect Dis J. 2007;26:667–671
45. Lepoutre A, Varon E, Georges S, et al. Impact of Infant Pneumococcal Vaccination on Invasive Pneumococcal Diseases in France, 2001–2006. Euro Surveill. 2008;13:367–372
46. Committee on Infectious Diseases. . Policy statement: recommendations for the prevention of pneumococcal infections, including the use of pneumococcal conjugate vaccine (prevnar), pneumococcal polysaccharide vaccine, and antibiotic prophylaxis. Pediatrics. 2000;106:362–6
47. von Gottberg A, Cohen C, de Gouveia L, et al. Early, direct effects of two doses of the 7-valent pneumococcal conjugate vaccine (PCV7) in South Africa, 2007–2009. 7th International Symposium on Pneumococci and Pneumococcal Disease. March 14–18, 2010 Tel Aviv, Israel Abstract 156
48. Deloria Knoll M, Park DE, Johnson TS, et al. Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on immunogenicity. Pediatr Infect Dis J. 2014;33 (Suppl 2):S119–S129
49. Fleming-Dutra KE, Conklin L, Loo JD, et al. Systematic review of the effect of pneumococcal conjugate vaccine dosing schedules on vaccine-type nasopharyngeal carriage. Pediatr Infect Dis J. 2014;33 (Suppl 2):S152–S160
50. von Gottberg A, Cohen C, Whitelaw A, et al.Group for Enteric, Respiratory, Meningeal Disease Surveillance in South Africa (GERMS-SA). Invasive disease due to Haemophilus influenzae
serotype b ten years after routine vaccination, South Africa, 2003-2009. Vaccine. 2012;30:565–571
51. Ladhani SN. Two decades of experience with the Haemophilus influenzae
serotype b conjugate vaccine in the United Kingdom. Clin Ther. 2012;34:385–399
52. Rückinger S, van der Linden M, Reinert RR, et al. Efficacy of 7-valent pneumococcal conjugate vaccination in Germany: an analysis using the indirect cohort method. Vaccine. 2010;28:5012–5016
53. Park SY, Van Beneden CA, Pilishvili T, et al.Active Bacterial Core surveillance team. Invasive pneumococcal infections among vaccinated children in the United States. J Pediatr. 2010;156:478–483.e2
54. Ota MO, Akinsola A, Townend J, et al. The immunogenicity and impact on nasopharyngeal carriage of fewer doses of conjugate pneumococcal vaccine immunization schedule. Vaccine. 2011;29:2999–3007
55. Russell FM, Carapetis JR, Satzke C, et al. Pneumococcal nasopharyngeal carriage following reduced doses of a 7-valent pneumococcal conjugate vaccine and a 23-valent pneumococcal polysaccharide vaccine booster. Clin Vaccine Immunol. 2010;17:1970–1976
56. Russell FM, Balloch A, Tang ML, et al. Immunogenicity following one, two, or three doses of the 7-valent pneumococcal conjugate vaccine. Vaccine. 2009;27:5685–5691
57. Dagan R, Givon-Lavi N, Porat N, et al. The effect of an alternative reduced-dose infant schedule and a second year catch-up schedule with 7-valent pneumococcal conjugate vaccine on pneumococcal carriage: a randomized controlled trial. Vaccine. 2012;30:5132–5140
58. Lucero MG, Dulalia VE, Parreno RN, et al. Pneumococcal conjugate vaccines for preventing vaccine-type invasive pneumococcal disease and pneumonia with consolidation on x-ray in children under two years of age. Cochrane database Syst Rev. 2004:CD004977
59. Klugman K, Cutts FT, Adegbola R, et al. Pneumococcal Vaccines: The Impact of Conjugate Vaccine. 2008 Washington DC ASM Press
60. Klugman KP, Madhi SA, Adegbola RA, et al. Timing of serotype 1 pneumococcal disease suggests the need for evaluation of a booster dose. Vaccine. 2011;29:3372–3373
61. Technical Advisory Group on Vaccine-Preventable Diseases.. Final Report July 6–8, 2011 Buenos Aires, Argentina Pan American Health Organization
62. World Health Organization. . Meeting of the Strategic Advisory Group of Experts on Immunization, November 2011—conclusions and recommendations. Wkly Epidemiol Rec. 2012;87:1–16
63. Bjornson G, Scheifele DW, Bettinger J, et al. Effectiveness of pneumococcal conjugate vaccine in Greater Vancouver, Canada: 2004–2005. Pediatr Infect Dis J. 2007;26:540–542
pneumococcal conjugate vaccine; immunization schedule; invasive disease; systematic review
© 2014 by Lippincott Williams & Wilkins, Inc.
Highlight selected keywords in the article text.