Trial assessing impact of vaccination with a pneumococcal conjugate vaccine on nasopharyngeal carriage of pneumococci

Lead Research Organisation: MRC Unit, The Gambia


Pneumonia is one of the most important causes of serious illness among children in The Gambia caused by a germ. There are roughly 90 different types of these pneumococcal bacteria and these can spread from person to person through close contact. It is likely that a new vaccine (Prevenar R) will soon be introduced into childhood immunization programme in The Gambia. This vaccine can work only on seven types but does not contain two forms of the germ that are important causes of invasive disease in The Gambia. In addition, there are concerns that the disease could re-emerge if children were infected with the other types of pneumococcal not covered in the original vaccine. We want to determine whether the introduction of this vaccine into a community will result in an increase in the carriage rate of these germs in the nose and throat without apparent disease and compare it to the germs in the nose and throat of children who did not receive this vaccine but a vaccine that prevent meningitis as a control. Swabs will be collected from the throats by a small stick with wool on the end one to three times a year. Some members of the household will contribute a small volume of blood and saliva before and after vaccination and subsequently at 3, 12 and 24 months after the completion of the first round of vaccination.

Technical Summary

Streptococcus pneumoniae is responsible for many deaths in young children in developing countries. The development of pneumococcal polysaccharide/protein conjugate vaccines offers a possible way of preventing these infections and results from initial trials are encouraging. It is likely that Prevenar R, a seven-valent pneumococcal conjugate vaccine, will soon be introduced into childhood immunization programme in The Gambia. Pneumococci of serotypes 1 or 5 are important causes of invasive disease in The Gambia but are found infrequently in the nasopharynx and are not contained in Prevenar R. Could introduction of Prevenar R enhance their ability to establish themselves in the nasopharynx and subsequently to cause invasive disease? For these reasons it is essential to determine whether the introduction of Prevenar R into a community where type 1 and type 5 pneumococci are important causes of invasive disease will result in an increase in the nasopharyngeal carriage rate of these and other pneumococcal serotypes, not contained in this vaccine. In order to study the effects of maximum immune pressure of the kind that will be seen only several years after routine use of the vaccine we propose to study the effects of vaccination of a whole community as well as that of vaccinating just the infant population.


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Bottomley C (2013) A mathematical model of serotype replacement in pneumococcal carriage following vaccination. in Journal of the Royal Society, Interface

Description Short and Long-term Impact Evaluation Framework on PCV Vaccines
Geographic Reach Africa 
Policy Influence Type Participation in advisory committee
Description Travel award for the ISPPD7
Amount £3,000 (GBP)
Organisation Pfizer Ltd 
Sector Private
Country United Kingdom
Start 03/2010 
End 03/2010
Title Biological samples 
Description Nasopharyngeal aspirates, blood and saliva samples were collected as part of the study in the years 2006, 2007 and 2008. As part of an ancillary study proposed (that is using the same initial funding) new nasopharyngeal aspirates were collected during 2010. 
Type Of Material Biological samples 
Year Produced 2011 
Provided To Others? No  
Impact Bacterial isolates resulting from the nasopharyngeal aspirates. For the last cross-sectional performed (2010) the laboratory analysis is ongoing. For the blood and saliva samples, that is also being generated 
Title Datasets 
Description Several study's datasets created as part of the trial. Most of the datasets are already cleaned and kept in the local server while others are in cleaning process 
Type Of Material Improvements to research infrastructure 
Year Produced 2012 
Provided To Others? No  
Impact These datasets are being used for statistical analysis (in progress) 
Description Pneumococcal population dynamics 
Organisation Bill and Melinda Gates Foundation
Country United States 
Sector Charity/Non Profit 
PI Contribution Provide samples and expertise to an international collaboration group
Collaborator Contribution All groups provide samples for a multi-site analysis
Impact Outputs not yet available
Start Year 2014
Description Community activity 
Form Of Engagement Activity Participation in an activity, workshop or similar
Part Of Official Scheme? No
Geographic Reach Local
Primary Audience Participants in your research and patient groups
Results and Impact A community activity was performed to inform all the study villages in rural The Gambia of the potential public health benefits of the study. Key people from the community was invited to help us to engage all the community participants. Progress of the study have been annually presented.

Very high community participation on the study.
Year(s) Of Engagement Activity 2006,2008,2009,2010
Description Education activity on herd effect of pneumococcal vaccines 
Form Of Engagement Activity A press release, press conference or response to a media enquiry/interview
Part Of Official Scheme? No
Geographic Reach International
Primary Audience Schools
Results and Impact A publication which resulted from this project was used for the RC-UK to develop, with the help of Anna Roca, educational material for high schools on herd effect of pneumococcal vaccines and design of vaccine trials.
Year(s) Of Engagement Activity 2016
Description Unit seminar: Impact of PCV vaccination on pneumococcal carriage in The Gambia 
Form Of Engagement Activity A talk or presentation
Part Of Official Scheme? No
Type Of Presentation Paper Presentation
Geographic Reach Local
Primary Audience Other academic audiences (collaborators, peers etc.)
Results and Impact 100 peers attended the talk. Discussion on results and implications for the uptake of pneumococcal vaccines in The Gambia

Year(s) Of Engagement Activity 2013