Abstract
Streptococcus pneumoniae is a significant cause of otitis media, pneumonia, and meningitis. Only seven of the approximately 100 serotypes were initially included in the pneumococcal polysaccharide conjugate vaccine (PCV) in 2000 before it was expanded in subsequent years. Although the invasive pneumococcal disease (IPD) incidence due to vaccine serotypes (VT) has declined, partial replacement by non-vaccine serotypes (NVT) was observed following widespread vaccine uptake. We conducted a trend analysis assembling the available evidence for PCV impact on European, North American and Australian national IPD. Significant effectiveness against VT IPD in infants was observed, although the impact on national IPD incidence varied internationally due to serotype replacement. Currently, NVT serotypes 8, 9N, 15A and 23B are increasing in the countries assessed, although a variety of other NVTs are affecting each country and age group. Despite these common emerging serotypes, there has not been a dominant IPD serotype post-vaccination as there was pre-vaccination (serotype 14) or post-PCV7 (serotype 19A), suggesting that future vaccines with additional serotypes will be less effective at targeting and reducing IPD in global populations than previous PCVs. The rise of diverse NVTs in all settings’ top-ranked IPD-causing serotypes emphasizes the urgent need for surveillance data on serotype distribution and serotype-specific invasiveness post-vaccination to facilitate decision making concerning both expanding current vaccination programmes and increasing vaccine valency.
Highlights
Streptococcus pneumoniae is a significant cause of otitis media, pneumonia, and meningitis
While PCV7 was implemented in various years, the higher valent vaccines (PCV10/13) were implemented in 2010 or 2011 for all countries
Overall national invasive pneumococcal disease (IPD) incidence decreased in all countries following the introduction of PCV7 and PCV10/13
Summary
Streptococcus pneumoniae is a significant cause of otitis media, pneumonia, and meningitis. NVT serotypes 8, 9N, 15A and 23B are increasing in the countries assessed, a variety of other NVTs are affecting each country and age group Despite these common emerging serotypes, there has not been a dominant IPD serotype post-vaccination as there was pre-vaccination (serotype 14) or postPCV7 (serotype 19A), suggesting that future vaccines with additional serotypes will be less effective at targeting and reducing IPD in global populations than previous PCVs. The rise of diverse NVTs in all settings’ top-ranked IPD-causing serotypes emphasizes the urgent need for surveillance data on serotype distribution and serotype-specific invasiveness post-vaccination to facilitate decision making concerning both expanding current vaccination programmes and increasing vaccine valency. Vaccination of children has reduced IPD in both vaccinated and unvaccinated populations, as children are the main reservoir of infection, and as such the unvaccinated age groups benefit from the removal of vaccine serotypes in children[7,8,9,10,11,12,13] Combined, these facts highlight the importance of vaccine development targeted at pneumococcal disease. The final aim is to identify potential candidates for serotypes that should be included in conjugate vaccines given increasing evidence on the invasiveness of the replacement serotypes
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