Most invasive pneumococcal disease caused by non-vaccine serotypes

By Reuters Staff

NEW YORK (Reuters Health) - Most invasive pneumococcal disease (IPD) in children with underlying medical conditions is caused by serotypes not included in any of the conjugate pneumococcal vaccines, researchers report.

In February 2013, the Advisory Committee on Immunization Practices recommended routine use of the 13-valent conjugate vaccine (PCV13) for children aged 6 to 18 years with immunocompromising conditions, functional or anatomic asplenia, cerebrospinal fluid leaks, or cochlear implants, regardless of whether they had received the 7-valent (PCV7) or 23-valent polysaccharide pneumococcal vaccine (PPV23).

Dr. Inci Yildirim and colleagues from Boston University in Massachusetts evaluated the epidemiology of IPD in Massachusetts children with selected comorbid illnesses in an effort to define the magnitude of their increased risk and the spectrum of serotypes causing disease.

In the 12 years ending in April 2014, there were 1052 cases of IPD in Massachusetts children under age 18 years. Children with comorbidities accounted for 22.1% of those cases, according to the February 2 Pediatrics online report.

The odds of an IPD case having comorbidity was 2.8 times higher in children 5 years or older than in younger children, and the proportion of IPD cases with underlying conditions did not change by study year, gender, or race.

The clinical presentation of IPD was similar for children with and without underlying conditions, but children with underlying conditions were twice as likely to be hospitalized and more than three times as likely to die.

In the last two years of the study, half of IPD cases among children with comorbidities were caused by serotypes in PPV23 that are not in the other vaccines, and half were caused by serotypes that are not included in any of the vaccines. No cases were caused by serotypes in PCV7 or PCV13 during these two years.

Compared with children without underlying conditions, those with comorbidities were more likely to have IPD caused by serotypes with lower invasive capacity.

The average annual risk of IPD was about 50-fold higher in children with sickle cell disease and about 33-fold higher in children with hematologic malignancies.

"Unfortunately," the researchers note, "in our study, pneumococcal vaccination (both PPV23 and PCV13) coverage was very low in children with comorbidity. It follows that there is a need for education of both health care providers and the families regarding the importance of vaccination in high-risk children."

"We need more insight into the role of PPV23 in protecting children with underlying conditions and new strategies to provide broader coverage among children who are at highest risk for pneumococcal infection and fatal outcomes," the authors conclude.

Dr. Yildirim did not respond to a request for comments.

This work was presented in part at the 9th International Symposium on Pneumococci and Pneumococcal Diseases, Hyderabad, India, March 8-13, 2014.

Two authors report receiving support from pharmaceutical companies; no other authors report any disclosures. This research had no external funding.

SOURCE: http://bit.ly/16hZqoA

Pediatrics 2015.

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