Pneumococcal vaccine less effective in children with comorbidities

By David Douglas

NEW YORK (Reuters Health) - Children with comorbidities may have higher rates of invasive pneumococcal disease caused by nonvaccine serotypes after receiving 13-valent pneumococcal conjugate vaccine (PCV13), a new study suggests.

As Dr. Pui-Ying Iroh Tam told Reuters Health by email, "Continued research into new pneumococcal vaccines is still needed to address the issue of serotype replacement disease, but our results suggest that we may need to prioritize management strategies for patients with comorbidities who are at higher risk for, and have increased morbidity from, disease."

To examine the impact of PCV13, Dr. Tam of University of Minnesota Children's Hospital in Minneapolis and colleagues studied data on Massachusetts children before (2007-2009) and after introduction of the vaccine (2010-2012). All were aged 5 years or less.

PCV13 serotypes declined by 18% in the first 2 years after PCV13 introduction, according to the July 7 online paper in Pediatrics. In addition, although differences did not reach significance, a higher proportion of children were hospitalized (57.6% vs. 50.6%), and a higher proportion of children had comorbidity (23.5% vs. 19.6%) in the post-PCV13 phase.

Children with comorbidities had higher rates of invasive pneumococcal disease (IPD) caused by a nonvaccine type (27.6% vs. 17.2%). They were also significantly more likely to be hospitalized (80.4% vs. 50.0%) and had a significantly longer median hospital stay (3.0 days vs. 0.5 days).

The most common serotypes in the pre-PCV13 era, say the investigators, were 19A (39.9%) and 7F (9.5%). PCV13 serotypes made up 51% of cases of IPD in the pre-PCV13 era and decreased to 33% in the first 2 years after PCV13.

Among the most prevalent comorbidities were chronic lung disease, malignancy or immunosuppressive therapy, and asthma.

Overall, the researchers conclude, "Routine vaccination with PCV13 may not be sufficient to reduce the risk of invasive disease in patients with comorbidity, and administering 23-valent pneumococcal polysaccharide vaccine to all children with comorbidity at the earliest acceptable age should be considered."

Commenting on the findings by email, Dr. Anna M. M. van Deursen of Wilhelmina Children's Hospital, UMC Utrecht in the Netherlands told Reuters Health that the results "show the importance of ongoing surveillance after implementation of vaccines. Pneumococcal conjugate vaccines have led to important changes in invasive pneumococcal disease such as the rise in non-vaccine types."

Dr. van Deursen, who has conducted research into PCV13 immunogenicity, added that the study "suggests that children with comorbidities might be more likely to suffer from non-vaccine type pneumococcal disease. Which raises the question whether pneumococcal conjugate vaccines effectively protect the weakest children."

"Further surveillance," she concluded, "is needed to identify specific risk groups and evaluate long term effects. Moreover, we are in need of data on trends over time to properly evaluate long term effects of the implementation of new pneumococcal vaccines."

SOURCE: http://bit.ly/1qNhDRa

Pediatrics 2014.

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