Despite widespread use of 7-valent pneumococcal conjugate vaccine and an overall decline in rates of invasive pneumococcal disease, pneumonia, and pneumococcal pneumonia among children, disease rates remain high among children with chronic conditions, according to study findings in Clinical Infectious Diseases.
Stephen I. Pelton, MD, of Boston University Schools of Medicine and Public Health, and colleagues analyzed health care claims data from 2007 to 2010 to compare rates of pneumococcal disease among children with high-risk and at-risk conditions with rates among children without risk factors. Study participants were categorized into age groups (younger than 5 years or aged 5 to 17 years) and considered high-risk, at-risk, or have no at-risk/high conditions based on Advisory Committee in Immunization Practices (ACIP) and AAP recommendations.
Stephen I. Pelton
Most children had no chronic or immunocompromising conditions. About 7% of children in each age group had one or more at-risk conditions; less than 1% of each age group had a high-risk condition.
Among children aged younger than 5 years with at-risk conditions, 46% were premature or had low birth weight; 36% had asthma; 13% had chronic heart disease; and 12% had chronic lung disease. Thirteen percent of younger children had more than one at-risk condition. Among older children with at-risk conditions, 72% had asthma; 11% had neuromuscular or seizure disorders; and 5% had more than one at-risk condition.
Rates of invasive pneumococcal disease (IPD) were 11.2 and 40.1 times higher among younger and older high-risk children than children with no risk factors. Among children with at-risk conditions, rates for IPD were 1.8 and 3.3 times higher for each age group than rates for children with no risk.
Rates of pneumococcal pneumonia were also higher among high-risk children, by 6.8 and 8.9 for the younger and older age group; and by 2.6 and 2.9 for at-risk children of each age group.
Among children with asthma, rates and rate ratios for IPD and pneumococcal pneumonia increased more rapidly than rates for children with high-risk or at-risk conditions.
IPD rate ratios increased from 1.7 for younger, at-risk children with one condition to 4 for those with three or more conditions. Rate ratios for pneumococcal pneumonia increased from 2.1 among younger, at-risk children with one condition to 13.4 among those with three or more conditions.
Regarding older, at-risk children, IPD rate ratios increased from 3 to 32.1 as the number of conditions increased from one to three or more. Pneumococcal pneumonia rate ratios increased from 2.4 to 33.1 as the number of conditions increased from one to three or more.
Rates and rate ratios for all-cause pneumonia were similar to those for IPD and pneumococcal pneumonia.
These data demonstrate disease rates remain disproportionately high in children with high-risk and at-risk conditions, according to the researchers. In addition, they wrote, the increased risk of disease in high-risk and at-risk children is likely due to serotypes not covered in the 7-valent conjugate vaccine (Prevnar, Pfizer) rather than vaccine failure.
“We have identified a group of children who are at an increased risk for pneumococcal disease due to having medical conditions not currently included within the ACIP and AAP recommendations for prevention. These include children with asthma, especially those with moderate or severe disease, as well as children with asthma and concurrent morbidities such as lung or heart disease, diabetes, or neuromuscular disorders,” the researchers concluded.
- These data demonstrate that despite widespread use of PCV7 and an overall decline in IPD and pneumonia rates, disease rates remain disproportionately high in children <17 years old with high-risk conditions. The fold risk increased with the severity of the conditions, especially with asthma, the number of risk factors and the increasing age. Vaccine failure is an unlikely explanation for these findings. A more likely reason is increased risk of disease due to non-PCV7 serotypes. The introduction of PCV13 in all children <6 years old with selected chronic medical conditions and recommendations for its use in naïve children 6-18 years with HIV or asplenia, is likely to further decrease disease in high-risk children. However it is also likely that high-risk children will continue to suffer considerably form IPD and pneumonia caused by no-PCV13 pneumococcal serotypes, capable to cause disease mainly in compromised children, resulting in serotype replacement disease in these children. The role of additional dose of the 23-valent polysaccharide vaccine is questionable.
The authors have identified medical conditions, not currently included within the ACIP and AAP recommendations for prevention by PCVs. These include children with asthma (especially moderate and severe), neuromuscular disorders, prematurity/low birth weight, and the combination of two or three or more of these conditions.
What are the implications of this study? In the near future we may want to expand recommendation of PCV13 administration to the additional high-risk conditions pointed in the current study. In the future we may be able to expand PCV spectrum to include more than 13 serotypes. It is important also to study the potential role of influenza vaccines and maybe in the future RSV vaccines in prevention of secondary pneumococcal pneumonia in these high-risk children.
- Ron Dagan, MD
- Director, Pediatric Infectious Disease Unit
Soroka University Medical Center
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