The approvals of the 7-valent pneumococcal conjugate vaccine (PCV7) and the 13-valent PCV (PCV13) in 2000 and 2010, respectively, significantly reduced the rate of invasive pneumococcal infection (IPD) in children with sickle cell disease (SCD). The more recent 23-valent pneumococcal polysaccharide vaccine (PPSV23) and 15-, 20-, and 21-valent PCVs (PCV15, PCV20, PCV21) provide protection against 62%, 16%, 51%, and 92% additional IPD serotypes compared with PCV13, respectively.
According to a study, led by Thomas Adamkiewicz, over a span of 25 years, the Georgia Emerging Infections Program and Centers for Disease Control and Prevention Active Bacterial Core surveillance network recorded 104 cases of IPD in 3707 children aged <10 years with hemoglobin SS or hemoglobin SC, representing 6% of IPD in Black or African American children in a metropolitan Atlanta reference population. Adamkiewicz noted children with IPD and hemoglobin SS or SC were older compared with children with only IPD in the reference group (P<.001).
Outcomes Improve but IPD Potentially More Common in SCD
Investigators reported that IPD declined by 87% and 80% in children with hemoglobin SS aged 0-4 and 5-9 years, respectively, between the periods of 1994-1999 and 2010-2018. However, the incidence rate ratio of IPD between children with SCD and the reference population increased from 20.2 to 29.2 in the same period. That said, after 2002, children with hemoglobin SS and IPD had a decline in mortality rate from 14% to 3% and meningitis from 16% to 8%. Additionally, resistance to penicillin was more common in children with SCD prior to the approval of PCV7.
The effectiveness of PPSV23 plus 15A/15C against IPD serotypes not covered by PCV13 within 3 years of vaccination was 92% (95% CI, 40.8-99.0; P=.014), adjusted for age and hydroxyurea. Further, PCV15, PCV20, and the in-development PCV21/V116 could cover 16%, 51%, and 92%, respectively, of non-PCV13 serotype IPD in children with SCD.
Overall, Adamkiewicz and colleagues suggested that “although less frequent, IPD remains a life-threatening risk in children with SCD. Effective vaccines with broader coverage could benefit these children.”