Ear Protection: combo vaccine prevents some infections.

A vaccine that triggers immunity against two common bacteria can prevent many ear infections in babies, a European team of researchers reports.

Middle ear infections send roughly 20 million U.S. children, most of them infants, to the doctor every year. Recurrent infections sometimes lead to partial hearing loss and can require surgical implantation of tubes to improve fluid drainage.

In their test, the scientists enrolled about 4,900 healthy infants visiting 50 clinics across the Czech Republic and Slovakia. The team randomly assigned half the babies to get the new vaccine, called Streptorix, in four doses, starting around 3 months of age and ending by 15 months. As a control group, the other babies got shots that protect against hepatitis A but not ear infections.

The researchers recorded the children's clinic visits until age 2. In the period after the third vaccine dose, 499 of the controls were diagnosed with ear infections, compared with only 333 of those getting the new vaccine, the researchers report in the March 4 Lancet.

This is the first vaccine to combine parts of two bacteria called Haemophilus influenzae and Streptococcus pneumoniae, says coauthor Roman Prymula, an epidemiologist at the University of Defence in Hradec Kralove in the Czech Republic. Between them, the two microbes cause roughly two-thirds of middle ear infections.

A vaccine approved by the Food and Drug Administration in 2000 has already shown some effectiveness in averting ear infections. Marketed as Prevnar by Wyeth Pharmaceuticals in Collegeville, Pa., it had been designed to stop pneumonia, meningitis, and blood infections. The vaccine is made up of a nontoxic diphtheria protein attached to sugar molecules from seven strains of S. pneumoniae. A study by Finnish researchers subsequently found that babies getting the vaccine had fewer than half as many ear infections caused by those S. pneumoniae strains as did babies getting a control vaccine.

The newer vaccine broadens coverage by coupling sugar molecules from 11 S. pneumoniae strains to a protein taken from H. influenzae. It protected against infections caused by Streptococcus or by Haemophilus.

In babies, the immune system doesn't always identify bacterial sugar molecules as foreign, says Cynthia Whitney, an epidemiologist at the Centers for Disease Control and Prevention in Atlanta. Combining them with the protein "allows the immune system to recognize the vaccine," she says.

Although the new vaccine's immune coverage isn't complete, "it gives those of us who've spent most of our careers interested in the treatment and prevention of ear infections a lot of optimism," says Stephen I. Pelton, a pediatrician at Boston University Medical Center.

The long-term effectiveness of the vaccine hasn't yet been tested, but it may not matter. "If you can get a vaccine that works for the first 3 years of life, that would have a major impact," he says.

Prymula expects GlaxoSmithKline of Rixensart, Belgium, which makes the new vaccine, to seek regulatory approval for it in 2007.