TY - JOUR
T1 - Impact of pneumococcal conjugate vaccines on nasopharyngeal carriage and invasive disease among unvaccinated people
T2 - Review of evidence on indirect effects
AU - Davis, Stephanie M.
AU - Deloria-Knoll, Maria
AU - Kassa, Hilina T.
AU - O'Brien, Katherine L.
N1 - Funding Information:
The authors gratefully acknowledge the work of Jennifer Loo for provision of the literature search results. This study is part of the research of the PneumoCarr Consortium funded by the Grand Challenges in Global Health Initiative which is supported by the Bill & Melinda Gates Foundation , the Foundation for the National Institutes of Health , the Wellcome Trust and the Canadian Institutes of Health Research . We gratefully acknowledge the Pneumococcal Conjugate Vaccine Dosing Landscape project, a project of the Accelerated Vaccine Initiative, Technical Assistance Consortium-Special Studies. Support for the Pneumococcal Conjugate Vaccine Dosing Landscape Project, was provided by Program for Appropriate Technology in Health (PATH) through funding from the Global Alliance for Vaccines and Immunization (GAVI). The views expressed by the authors do not necessarily reflect the views of the GAVI Alliance and/or PATH.
PY - 2013/12/17
Y1 - 2013/12/17
N2 - Background: Invasive disease due to Streptococcus pneumoniae remains an important worldwide cause of morbidity and mortality, particularly in young children and the elderly. The development and use of pneumococcal conjugate vaccines (PCVs) have had a dramatic impact on rates of vaccine-type invasive pneumococcal disease (IPD) not only in the pediatric population targeted for vaccination but in non-vaccinated age-groups as well. This indirect effect is directly mediated by a reduction of vaccine-type nasopharyngeal carriage and thus transmission by vaccinated children. Current PCV licensing procedures do not take into consideration nasopharyngeal carriage impact, and thus the indirect effect. This review summarizes the evidence for the indirect effect of PCV on vaccine-type disease and its correlation with changes in carriage among unvaccinated populations, to assess the basis for inclusion of carriage in the PCV licensing process. Methods: Randomized controlled trials, surveillance and other observational studies published between 1994 and 2013 were systematically identified from global, regional and review databases and conference abstracts. We included as primary evidence, studies in non-vaccinated groups addressing changes in both vaccine-type IPD and carriage between pre- and post-PCV introduction periods; studies missing one of these four components were included as supporting rather than primary evidence. Results: We identified studies from 14 countries, nearly all developed countries. Vaccine-type IPD and carriage in non-targeted populations consistently decreased after PCV introduction, with the magnitude of decrease growing over time. Where IPD and carriage were observed in the same population, VT-decreases occurred contemporaneously. These relationships held true across age-groups and between indigenous and non-indigenous populations in the US and Australia. Conclusions: Indirect PCV impact on VT-IPD and VT-carriage has been significant. Impact on carriage should be considered for inclusion in the PCV licensure process as a predictor of indirect effects.
AB - Background: Invasive disease due to Streptococcus pneumoniae remains an important worldwide cause of morbidity and mortality, particularly in young children and the elderly. The development and use of pneumococcal conjugate vaccines (PCVs) have had a dramatic impact on rates of vaccine-type invasive pneumococcal disease (IPD) not only in the pediatric population targeted for vaccination but in non-vaccinated age-groups as well. This indirect effect is directly mediated by a reduction of vaccine-type nasopharyngeal carriage and thus transmission by vaccinated children. Current PCV licensing procedures do not take into consideration nasopharyngeal carriage impact, and thus the indirect effect. This review summarizes the evidence for the indirect effect of PCV on vaccine-type disease and its correlation with changes in carriage among unvaccinated populations, to assess the basis for inclusion of carriage in the PCV licensing process. Methods: Randomized controlled trials, surveillance and other observational studies published between 1994 and 2013 were systematically identified from global, regional and review databases and conference abstracts. We included as primary evidence, studies in non-vaccinated groups addressing changes in both vaccine-type IPD and carriage between pre- and post-PCV introduction periods; studies missing one of these four components were included as supporting rather than primary evidence. Results: We identified studies from 14 countries, nearly all developed countries. Vaccine-type IPD and carriage in non-targeted populations consistently decreased after PCV introduction, with the magnitude of decrease growing over time. Where IPD and carriage were observed in the same population, VT-decreases occurred contemporaneously. These relationships held true across age-groups and between indigenous and non-indigenous populations in the US and Australia. Conclusions: Indirect PCV impact on VT-IPD and VT-carriage has been significant. Impact on carriage should be considered for inclusion in the PCV licensure process as a predictor of indirect effects.
KW - Indirect effect
KW - Nasopharyngeal carriage
KW - Nasopharyngeal colonization
KW - Pneumococcal conjugate vaccine
KW - Pneumococcus
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U2 - 10.1016/j.vaccine.2013.05.005
DO - 10.1016/j.vaccine.2013.05.005
M3 - Article
C2 - 23684824
AN - SCOPUS:84891953345
SN - 0264-410X
VL - 32
SP - 133
EP - 145
JO - Vaccine
JF - Vaccine
IS - 1
ER -