Abstract
Declining mortality following invasive pneumococcal disease (IPD) has been observed concurrent with a reduced incidence due to effective pneumococcal conjugate vaccines. However, with IPD now increasing due to serotype replacement, we undertook a statistical analysis to estimate the trend in all-cause 30-day case fatality rate (CFR) in the North East of England (NEE) following IPD. Clinical, microbiological and demographic data were obtained for all laboratory-confirmed IPD cases (April 2006-March 2016) and the adjusted association between CFR and epidemiological year estimated using logistic regression. Of the 2510 episodes of IPD included in the analysis, 486 died within 30 days of IPD (CFR 19%). Increasing age, male sex, a diagnosis of septicaemia, being in ⩾1 clinical risk groups, alcohol abuse and individual serotypes were independently associated with increased CFR. A significant decline in CFR over time was observed following adjustment for these significant predictors (adjusted odds ratio 0.93, 95% confidence interval 0.89-0.98; P = 0.003). A small but significant decline in 30-day all-cause CFR following IPD has been observed in the NEE. Nonetheless, certain population groups remain at increased risk of dying following IPD. Despite the introduction of effective vaccines, further strategies to reduce the ongoing burden of mortality from IPD are needed.
Highlights
Invasive pneumococcal disease (IPD), caused by infection with the bacterium Streptococcus pneumoniae, is one of the most common causes of bacteraemic pneumonia, septicaemia and meningitis worldwide, with a substantial global burden in young children, older adults and those with certain co-morbidities [1, 2]
After exclusion of four cases who were either not permanent residents of North East of England (NEE) (n = 2) or where data within IPD Enhanced Surveillance System (IPDESS) were inconsistent with that retrieved during linkage to death data (n = 2), a total of 2510 IPD cases were included in the analysis (Table 1)
Despite recent increases in IPD in NEE in the epidemiological years 2014/2015 and 2015/2016, following a sustained period of reducing incidence [4], our study provides reassuring evidence that this increased incidence does not seem to be associated with the emergence of serotypes associated with worse outcomes
Summary
Invasive pneumococcal disease (IPD), caused by infection with the bacterium Streptococcus pneumoniae, is one of the most common causes of bacteraemic pneumonia, septicaemia and meningitis worldwide, with a substantial global burden in young children, older adults and those with certain co-morbidities [1, 2]. A single dose of 23-valent pneumococcal polysaccharide vaccine (PPV23) has been recommended for people at increased risk since 1992 and all individuals aged ⩾65 years since 2003. IPD incidence in NEE, and the UK as a whole, declined significantly after the introduction of PCV7 and PCV13 [4, 5]; reductions due to direct effects for those vaccinated and indirect (herd-level) effects for non-vaccinated age groups due to reduced carriage and transmission [6, 7]. The decline in PCV serotypes coincided with the emergence of non-PCV serotypes and the incidence of IPD increased for the first time in 2014/2015 and has done so consistently thereafter; suggesting the maximum benefit of the PCV programme may have been achieved [4, 5]. In addition to altered serotype dynamics, changes have been observed in the age profile of cases with increased incidence most pronounced in older age groups [4, 5]
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