Immunosuppressed patients, especially haematopoietic stem cell transplant (HSCT) recipients, are particularly vulnerable to invasive pneumococcal disease (IPD). However, uptake of pneumococcal vaccination tends to be lower in the immunosuppressed, partly due to concerns of vaccine effectiveness. Our institution introduced protocolised 10- or 13-valent conjugate pneumococcal vaccination (PCV) to all allogeneic and autologous HSCT recipients in 2010 to replace routine 23-valent polysaccharide vaccine (PPV23).
We conducted a retrospective single-centre observational study of all HSCT recipients from 2004 to 2015 to assess the impact of PCV introduction on IPD incidence. All HSCT recipients were reviewed for microbiological evidence of IPD following HSCT. The pre-2010 group of HSCT recipients who did not receive PCV, were compared to the post-2010 group of HSCT recipients who did receive PCV. Enrolment and compliance with the post-HSCT vaccination protocol was assessed.
Of the 917 HSCT screened for IPD, 14 episodes of IPD occurred in 12 patients between 2004 and 2016. Twelve episodes occurred in the pre-2010 group, 40% of serotyped isolates would have been covered by PCV. Two episodes occurred in the post-2010 group, neither isolate serotype was covered by PCV. There was >90% enrolment and vaccination protocol completion for surviving HSCT recipients.
Overall IPD rate reduced significantly from 31.9/1000 transplants pre-2010, to 3.7/1000 transplants post-2010 group (p<0.05). Specific reductions occurred in the autologous transplant group from 26.2 to 2.8/1000 transplants (p< 0.05) and the allogeneic transplant group from 45.5 to 5.3/1000 transplants (p<0.05).
Introduction of PCV resulted in a significant reduction in IPD among our high-risk cohort, demonstrating clinical effectiveness of PCV in HSCT recipients and confirming immunogenicity data. To our knowledge, this is the first study to demonstrate the clinical effectiveness of PCV in this group, highlighting the importance of this vaccination to prevent infectious complications following allogeneic and autologous HSCT. The clinical effectiveness of PCV vaccine is enhanced by the high quality of our post-HSCT vaccination program.
M. B. Roberts,
N. Bak, None
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