Lung Infection Up in Wake of Kids' Pneumonia Vaccine

January 15, 2010

HealthDay Thu Jan 14, 11:49 pm ET

THURSDAY, Jan. 14 (HealthDay News) -- Since the PCV7 early childhood vaccine for

bacterial pneumonia was introduced in the United States in 2000, the number of

children hospitalized for pneumonia because of pneumococcus has decreased by 50

percent and bacterial pneumonias have decreased overall, new research shows.

But the scientists also found a 70 percent increase in the rate of a pneumonia

complication called empyema, a serious and sometimes life-threatening infection

in a cavity between the lung and chest wall.

This dramatic rise in the incidence of empyema may partly be because the PCV7

eliminates certain types of pneumococcus, which provides an opportunity for more

virulent and antibiotic-resistant types of bacteria to take its place, said the

researchers at the University of California, , Children's Hospital.

The increase " may be occurring because the vaccine does not affect the types of

microorganisms causing empyemas, " study author Su-Ting T. Li, an assistant

professor in the pediatrics department, said in a news release. " The vaccine may

be getting rid of the pneumococcal bacteria that cause most pneumonia and other

types of invasive pneumococcal disease. But the bacteria that are left over that

[the vaccine] doesn't protect against that are more likely to cause empyema may

increase because they don't have to compete against the other pneumococcal

bacteria anymore. "

For their study, Li and colleagues analyzed data from the national Kids'

Inpatient Database for the years 1997, 2000, 2003 and 2006. From 1997 to 2006,

the empyema-associated hospitalization rate for children aged 18 and younger

increased 70 percent, from 2.2 per 100,000 to 3.7 per 100,000. The rate of

complicated pneumonia -- which includes empyema, pleural effusion or bacterial

pneumonia requiring a chest tube or decortication -- increased 45 percent

between 1997 and 2006, when the rate was 5.5 per 100,000.

From 1997 to 2006, the rate of bacterial pneumonia hospitalizations decreased 13

percent, to 244.3 per 100,000, and the rate of invasive pneumococcal disease --

pneumonia, sepsis or meningitis caused by Streptococcus pneumoniae -- decreased

50 percent to 6.3 per 100,000.

The mean age of children hospitalized with empyema decreased from slightly more

than seven in 1997 to just above six in 2006. Among children younger than 5, the

rate of empyema increased 100 percent, from 3.8 per 100,000 in 1997 to 7.6 per

100,000 in 2006.

The study appears in the January issue of Pediatrics.

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