Every time one problem gets solved, it seems another crops up. This is the case with the childhood pneumonia vaccine.

Since the vaccine was introduced almost a decade ago to stamp out bacterial pneumonia, there has been a big drop in that serious lung disease. But there has also been a dramatic increase in a serious and sometimes life-threatening complication, according to a new national study by researchers at UC Davis.

It seems this is the result of the vaccine eliminating certain types of pneumococcus, creating an opportunity for other bacteria to take its place.

The study is published in the January issues of the journal Pediatrics. It looked at the incidence of empyema, a complication of pneumonia that is a severe infection in a cavity between the lung and the chest wall.

There's been a 50 percent drop in hospitalizations from pneumonia due to pneumococcus since the vaccine was introduced in 2000, and an overall decrease in all bacterial pneumonias. But the empyema rate jumped 70 percent, according to the study.

The Food and Drug Administration licensed PCV7, a vaccine for infants and children, in 2000. It protected them from seven serotypes, or strains of microorganisms, most commonly responsible for serious infections from Streptococcus pneumoniae.

(We wrote a story recently about how the vaccine has been successful with kids, but adults have been underusing it. And that's been a problem because pneumonia is a common complication of the flu. Read that story here. )

Though responsible for less pneumonia overall, the serotypes not targeted by the vaccine may lead to more complicated pneumonias, such as empyema. In addition, the incidence of empyemas caused by staphylococcus, another bacterial cause of pneumonia not prevented by  pneumococcal vaccines, appears to be increasing. This may be due to more virulent and antibiotic-resistant forms of staphylococcus, such as methicillin-resistant staphylococcus aureus (MRSA).

"This may be occurring because the vaccine does not affect the types of microorganisms causing empyemas," said Li, an assistant professor in the Department of Pediatrics at UC Davis Children's Hospital, in a statement. "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 it 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."

Researchers said parents should still immunize their children because it targets the most common causes of pneumonia. Also, an expanded vaccine to cover the new problem is in the works.

What do you think? Would this put you off the vaccine for your child?

Baltimore Sun file photo of a pnuemonia vaccine/Jed Kirschbaum