Kids' Chest Infections Up Since Vaccine
Pneumococcal Vaccine Is Saving Lives, but Chest Infections Increasing
WebMD News Archive
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.