Impact of vaccination on invasive pneumococcal disease in adults with focus on the immunosuppressed

- IPD incidence significantly declined by 60% over the study period.
- A parallel decrease in the proportion of IPD isolates included in PCV7 and PCV13 vaccines was observed.
- Global vaccine coverage was for PCV7 21.6% vs. 28.8% in general and in the ISP and for PCV13, 64.5% and 56.6%, respectively.
- Penicillin resistance experienced a significant decline. No changes in mortality were detected.
- Coverage of PCV13 vaccine might be suboptimal for immunosuppressed population in the coming years.

SummaryPneumococcal conjugate vaccine (PCV13) has been recently added to the vaccine recommendations for immunosuppressed adults (ISP). We conducted a multicenter observational prospective study aimed to assess the evolving epidemiology of invasive pneumococcal disease (IPD) in adults, with especial focus on ISP. All IPD cases admitted from 1999 to 2014 were included. ISP was defined as patients on current cancer chemotherapy, immunosuppressive therapy for autoimmune disease, biological therapy, chronic systemic steroid use, hemodialysis, neutropenia or HIV infection. A total of 799 IPD episodes were analyzed, 198 were considered ISP. IPD incidence decreased from 20 to 8/100,000-population year (p < 0.004) over the study period. No changes in mortality were observed. Penicillin resistance experienced a significant decline. In 694 episodes the serotype was known. Global vaccine coverage considering the whole study period, was for PCV7 21.6% vs. 28.8% in general and in immunosuppressed population (p = 0.04) and for PCV13 64.5% and 56.6% respectively (p = 0.05). The proportion of IPD isolates included in PCV7 and PCV13 significantly decreased over time.A reduction in the incidence of IPD in adults was seen late after the vaccine licensure, both in general population and in ISP. Coverage of PCV13 vaccine might be suboptimal for ISP in the coming years.