Nancy A. Melville

May 20, 2015

LEIPZIG, Germany — The introduction of the 10-valent pneumococcal conjugate vaccine, PCV10, decreases the rates of clinical pneumonia even in unvaccinated children, according to new research.

This study is the first to report the impact of this vaccine in unvaccinated children, said lead author Jukka Jokinen, PhD, from the National Institute for Health and Welfare in Helsinki, Finland.

"If our observations reflect the impact of herd protection, the benefits of the pneumococcal vaccine in the unvaccinated population certainly exceeds our expectations," Dr Jokinen told Medscape Medical News here at the 33rd Annual Meeting of the European Society for Paediatric Infectious Diseases.

Dr Jokinen and his colleagues assessed pneumonia rates from 2011 to 2013 in 116,672 children.

For hospital-diagnosed pneumonia, there was a relative rate reduction of 12% (95% confidence interval [CI], 6 - 17) in the 2012/13 season, compared with the 2005/06 and 2007/08 seasons.

For hospital-treated primary pneumonia, there was a relative rate reduction of 28% (95% CI, 21 - 35) in the 2012/13 season, compared with the 2005/06 and 2007/08 seasons.

"This represents an absolute reduction of 90 cases per 100,000 person-years," Dr Jokinen reported.

Although the reduction is similar to that seen in rates of invasive pneumococcal disease in the same cohort, they are nevertheless a bit of a surprise, he explained.

 
The pneumonia reduction in unvaccinated children 2 to 5 years of age was much bigger than we expected.
 

"The pneumonia reduction in unvaccinated children 2 to 5 years of age was much bigger than we expected," he said.

"One must always be cautious when interpreting the results of observational studies, but if we assume these rate changes reflect the impact of PCV, PCV10 has reduced more pneumonia in older children solely through herd protection than PCV7 did through direct immunization plus herd protection," said Dr Jokinen.

Herd Immunity

"Surveillance data in the coming years will shed more light on the full potential of PCV10 in reducing pneumonia and other pneumococcal disease in the unvaccinated population," Dr Jokinen added.

As vaccines evolve, similar improvements can be expected, and in fact have been seen around the world, said Marie Griffin, MD, from Vanderbilt University, who was not involved in the study.

"With the greater number of serotypes in current vaccines, there has been more disease reduction for both vaccinated and unvaccinated populations," she told Medscape Medical News.

In the United States, improvements were seen between the introduction of PCV7 in 2000 and the introduction of the PCV13 in 2010. "PCV10 reduces more disease than PCV7, and PCV13 reduces more disease than PCV10," she said.

However, because "there are more than 90 pneumococcal strains and current vaccines protect against only a minority, it is very important to continue monitoring trends in pneumococcal diseases," Dr Griffin said.

In the United States, after the introduction of PCV7, there was a 12.5% reduction in pneumonia hospitalization in 2- to 4-year-old children, she reported.

"In the Finnish study, there appears to be an earlier but similar decrease in pneumonia hospitalizations in this age group, but it will be important to look at long-term trends," she added.

This study was funded by the National Institute for Health and Welfare in Finland. Dr Jokinen is a coinvestigator in the FinIP trial of the PCV10 vaccine, which is mainly funded by GlaxoSmithKline Biologicals. Dr Griffin reports receiving funding from the Centers for Disease Control and Prevention to study trends in pneumonia.

33rd Annual Meeting of the European Society for Paediatric Infectious Diseases (ESPID). Abstract 0829. Presented May 4, 2015.

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