Invasive pneumococcal disease in Portugal prior to and after the introduction of pneumococcal heptavalent conjugate vaccine

Abstract

The rates of invasive pneumococcal disease (IPD), serotype distribution and antimicrobial susceptibility prior to and after the introduction of the heptavalent pneumococcal conjugate vaccine in Portuguese children were evaluated. The changes in incidence of IPD in children under 1 year old between the two periods of the study was not significant (P=0.53), despite the 21% decline. In children under 18 years old there was a 27.7% decrease in vaccine serotypes. All nonvaccine serotypes increased 71.4%. The decrease in vaccine serotypes was more impressive during the first year of life (-54.8%) than for children between 1 and 5 years of age (-19.1%). Among children under 1 year old, penicillin nonsusceptible isolates declined between the two periods of the study (47.2% vs. 25.0%) (P=0.03), as did those of cefotaxime and ceftriaxone nonsusceptible isolates. No changes were observed for isolates nonsusceptible to tetracycline and macrolides. The serotypes of these nonsusceptible isolates differed after the introduction of vaccine (P=0.01). Multiresistance increased 57.1% after the introduction of vaccine. Multiresistant isolates with vaccine serotype declined 42.9% (P<0.001), and nonvaccine serotypes appeared during the vaccination period (P<0.001). These findings suggest a replacement of vaccine serotypes by nonvaccine serotypes, mainly among nonsusceptible isolates.

Temporal Analysis of Invasive Pneumococcal Clones from Scotland Illustrates Fluctuations in Diversity of Serotype and Genotype in the Absence of Pneumococcal Conjugate Vaccine

“…In the United States, clonal expansion (the increase in the number of previously rare clones expressing nonvaccine serotypes) has also been documented (2). Nonvaccine serotypes have been reported in a number of postvaccine studies (11,23,27). It is not clear whether such changes are directly driven by vaccine pressure or are due in some part to the natural fluctuations that occur in this naturally transformable species.…”

Epidemiology of Invasive Pneumococcal Disease among Adult Patients in Barcelona Before and After Pediatric 7‐Valent Pneumococcal Conjugate Vaccine Introduction, 1997–2007

“…In France, a 21% decrease in IPD among children aged !2 years was observed in 2006 after PCV7 introduction (coverage, 68%; uptake, 44%), whereas the overall rate of IPD among adults increased [27]. In Portugal, with a PCV7 uptake of 54%, the rate of IPD among children aged !1 year decreased by 21% in the period 2002-2004, although the decrease was not statistically significant ( ) [28]. In P p .53 Spain, PCV7 covered 68% of the serotypes that were causing IPD in children during the prevaccine period [13,20], and the estimated PCV7 uptake among children aged !2 years was 22%-29% in 2002-2004 and increased to 45%-50% in 2005-2006 [13-17].…”

Ten-year surveillance of invasive Streptococcus pneumoniae isolates in central Turkey prior to the introduction of a conjugate vaccine

“…Recent data have shown that the use of the 7-valent conjugate vaccine is very effective in reducing not only invasive infections but also carriage of vaccine serotypes in the nasopharynx of vaccinated children [17][18]. Although vaccine use causes an Figure 2.…”

“…increase in herd immunity and a reduction in the number of vaccine-related diseases, the greatest concern is a possible increase in invasive pneumococcal diseases caused by non-vaccine serotypes resulting from the selective pressure of the vaccine [18][19][20]. In this regard, Martens et al [16] have reported that capsular serotypes influenced the outcome of invasive pneumococcal diseases and that infection with serotype 3 resulted in an increased relative risk of death, whereas infection with serotype 1 was associated with a decreased risk of death.…”