Abstract
The 10-valent pneumococcal conjugate vaccine (PCV10) became available in Portugal in mid-2009 and the 13-valent vaccine (PCV13) in early 2010. The incidence of invasive pneumococcal disease (IPD) in patients aged under 18 years decreased from 8.19 cases per 100,000 in 2008–09 to 4.52/100,000 in 2011–12. However, IPD incidence due to the serotypes included in the 7-valent conjugate vaccine (PCV7) in children aged under two years remained constant. This fall resulted from significant decreases in the number of cases due to: (i) the additional serotypes included in PCV10 and PCV13 (1, 5, 7F; from 37.6% to 20.6%), particularly serotype 1 in older children; and (ii) the additional serotypes included in PCV13 (3, 6A, 19A; from 31.6% to 16.2%), particularly serotype 19A in younger children. The decrease in serotype 19A before vaccination indicates that it was not triggered by PCV13 administration. The decrease of serotype 1 in all groups, concomitant with the introduction of PCV10, is also unlikely to have been triggered by vaccination, although PCVs may have intensified and supported these trends. PCV13 serotypes remain major causes of IPD, accounting for 63.2% of isolates recovered in Portugal in 2011–12, highlighting the potential role of enhanced vaccination in reducing paediatric IPD in Portugal.
Highlights
Introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) led to changes in the circulating serotypes of Streptococcus pneumoniae and often to decreases in the incidence of invasive pneumococcal disease (IPD) worldwide [1,2,3]
This fall resulted from significant decreases in the number of cases due to: (i) the additional serotypes included in PCV10 and PCV13 (1, 5, 7F; from 37.6% to 20.6%), serotype 1 in older children; and (ii) the additional serotypes included in PCV13 (3, 6A, 19A; from 31.6% to 16.2%), serotype 19A in younger children
We showed that significant changes in the serotypes causing IPD in children followed PCV7 availability in Portugal [9,10] and that there was evidence for a herd effect in the adult population [9,11,12]
Summary
Introduction of the 7-valent pneumococcal conjugate vaccine (PCV7) led to changes in the circulating serotypes of Streptococcus pneumoniae and often to decreases in the incidence of invasive pneumococcal disease (IPD) worldwide [1,2,3]. Two new pneumococcal conjugate vaccine (PCV) formulations are commercially available and are used for children [4]. The few available early reports point to the effectiveness of these expanded valency vaccines against the serotypes included in their formulations [4,5,6,7,8]. In Portugal, PCVs are not included in the national immunisation plan. Had they been, they would have been offered free of charge. Since 2001, when the vaccine became available, there has been a steady increase in PCV7 uptake bought privately, without any reimbursement, reaching 75% of children aged 2 years or under in 2008 [9]. Soon after PCV13 became available, according to sales data, this vaccine was mostly used (data not shown)
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