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Published on: February 23, 2014
Serotype specific pneumococcal vaccine effectiveness in children with sickle cell disease: A two-decade analysis
Ziyu Zhang1, Melike Yildirim2, Pinar Keskinocak1
1H. Milton Stewart School of Industrial and Systems Engineering, Atlanta, GA, USA; Center for Health and Humanitarian Systems, Georgia Institute of Technology, Atlanta, GA, USA.
Insights
Children with sickle cell disease (SCD) still face higher invasive pneumococcal disease (IPD) rates post-vaccination. Remaining IPD cases are linked to serotypes not covered by current vaccines, suggesting a need for broader vaccine strategies.
Area of Science:
- Pediatric Hematology
- Infectious Diseases
- Vaccinology
Background:
- Sickle cell disease (SCD) is a prevalent global genetic blood disorder.
- Children with SCD have a significantly elevated risk of invasive pneumococcal disease (IPD).
Purpose of the Study:
- To assess the impact of pneumococcal conjugate vaccines (PCV13) on IPD incidence in children with SCD.
- To evaluate vaccine effectiveness and identify serotypes responsible for breakthrough IPD in this population.
Main Methods:
- Utilized population-based surveillance data for IPD in children under 18 in Massachusetts (2002-2020).
- Calculated incidence rates (IR) and incidence rate ratios (IRR) for pre- and post-PCV13 periods.
- Determined vaccine effectiveness (VE) and predicted PCV13 vaccine failure using a random forest model.
Main Results:
- Children with SCD exhibited substantially higher IPD IRs than healthy children in both pre- and post-PCV13 eras.
- PCV13 showed a modest reduction (28.1%) in overall IPD for children with SCD, compared to 59.5% in healthy children.
- A significant proportion (61.1%) of remaining IPD cases in children with SCD were caused by non-PCV13 serotypes, indicating potential for expanded valency vaccines.
Conclusions:
- Despite vaccination, children with SCD remain at higher risk for IPD.
- Serotypes not covered by PCV13 are responsible for the majority of ongoing IPD in this cohort.
- Expanded valency vaccines and risk-stratified vaccination approaches are crucial for protecting children with SCD.
Objectives:
Sickle cell disease (SCD) is the most common genetic hematologic disease globally and children with SCD are at increased risk for pneumococcal disease.
Methods:
We utilized data from population-based enhanced surveillance for invasive pneumococcal disease (IPD) in children <18 years of age in Massachusetts from 2002 to 2020. We calculated incidence rates (IR) among children with SCD using bootstrapping resampling and incidence rate ratios (IRR) for pre- and post-PCV13 periods. Vaccine effectiveness (VE) was calculated as 100*(1-IRR), and PCV13 vaccine failure probability was predicted using a random forest model.
Results:
Children with SCD had higher IR during both pre-/post-PCV13 periods compared with otherwise healthy children 240.0/100,000 versus 4.6/100,000 in pre-PCV13 period (2002-2009); 172.7/100,000 versus 1.9/100,000 in post-PCV13 period (2011-2020), respectively. After widespread use of PCV7 for a decade, a modest reduction of 28.1 % (95% CI 25.9-37.2%) in the incidence of overall IPD during the post-PCV13 period was observed in children with SCD, whereas a more substantial 59.5% (96% CI 57.8-61.4%) reduction was observed in otherwise healthy children. There was a 60.8% (95% CI 55.2%-NA) reduction in the incidence of VST13 IPD in children with SCD and an 83.0% (95% CI 80.67-85.63%) reduction in children without underlying health condition. Overall, 61.1% of the remaining IPD among children with SCD were due to non-PCV13 serotypes (8, 10A, 15A,15B, 22F, 23B), many of which are included in expanded valency vaccines.
Conclusion:
Children with SCD continue to have higher rates of IPD compared with otherwise healthy children despite vaccination. Majority of the remaining disease is due to serotypes not included in vaccine formulations that have been used for the last two decades. Our study highlights the potential value of expanded valency vaccines and importance of risk-based vaccination strategies tailored for this vulnerable population.
