Kids' Chest Infections Up Since Vaccine

Jan. 19, 2010 - Childhood pneumococcal vaccination may be linked to an
increase in a serious complication of pneumonia, a new study suggests.
The proven benefit of the vaccine -- which since its introduction in 2000
has slashed rates of pneumonia, bacterial meningitis, and blood infections in
children -- far outweighs this possible risk.
But could an otherwise good vaccine cause a rise in empyema, a serious
infection? Yes, suggest findings from Su-Ting Li, MD, MPH, and Daniel J.
Tancredi, PhD, of the University of California, Davis. The researchers analyzed
national data on hospitalized U.S. kids.
As expected, the rate of invasive pneumococcal disease dropped by 50%
between 1997 and 2006. But the rate of empyema increased 70%.
"Part of this may be that when the vaccine eliminated those subtypes of
pneumococcal bacteria most likely to cause pneumonia, meningitis, and sepsis,
it reduced the competition so that other subtypes could increase and cause
empyema," Li tells WebMD.
Empyema is a complication of pneumonia that begins on the outside of
the lung. Eventually a sticky mass of pus develops in the chest, making
breathing difficult and painful.
There are a lot of different germs that can cause empyema, but the most
common cause is Streptococcus pneumoniae -- the very same bug that the
pneumococcal vaccine targets.
But there are more than 90 strains of pneumococci. The current vaccine,
Prevnar, covers the seven strains most likely to cause pneumonia, meningitis,
and blood infections. It does not cover the strain most likely to cause
empyema.
That may change. Li notes that a new version of the pneumococcal vaccine
will soon be approved. The new vaccine covers 13 strains of pneumococcus --
including the subtype most likely to cause empyema.
Pediatric infectious disease expert Geoffrey Weinberg, MD, of the University
of Rochester, N.Y., notes that methods used by Li and colleagues don't
definitively prove that empyema is on the rise. Nevertheless, he feels the data
do suggest an increase in empyema.
Weinberg agrees that some of the increase may be due to pneumococcal strains
not included in the older version of the vaccine. But he also notes that
infections with drug-resistant staph, aka MRSA, are on the rise and may
contribute to the rise in empyema.
"I think they are probably right that empyema hospitalizations have gone up
somewhat, but I don't want to lose the message that bad meningitis, death, and
bloodstream infections caused by pneumococci have gone way down," he says.
"There now are about 30,000 fewer pneumonia hospitalizations compared to about
1,200 more cases of empyema."
Li and Tancredi have no financial relationships relevant to the study.
Weinberg is on the speakers' bureau for several vaccine makers, although not
Wyeth, which makes Prevnar pneumococcal vaccine. The University of Rochester
receives royalties related to the invention of the pneumococcal vaccine, but
Weinberg does not share in these funds.
The Li and Tancredi paper appears on the January issue of
Pediatrics.
http://children.webmd.com/vaccines/news/20100119/kids-chest-infections-up-since-vaccine?src=RSS_PUBLIC