Updated

U.S. regulators on Thursday approved a new children's vaccine from GlaxoSmithKline PLC that targets two common causes of bacterial meningitis, which can be fatal.

The U.S. Food and Drug Administration said the vaccine, MenHibrix, is meant for children aged six weeks to 18 months and combines vaccines for meningococcal disease and Hib disease. The diseases are common causes of the infection.

The FDA had rejected MenHibrix twice before, in 2010 and 2011, but GlaxoSmithKline said it had resolved regulators' questions about the vaccine's potency and efficacy.

Bacterial meningitis is a serious infection of the thin lining surrounding the brain and spinal cord. It can cause severe brain damage and is fatal in 50 percent of cases if untreated.

About 4,100 cases of bacterial meningitis occurred in the United States each year from 2003 to 2007 - the most recent data available - and 500 people died from the disease, according to the Centers for Disease Control and Prevention. Infants are at highest risk.

The FDA said the disease can progress rapidly in children who are not vaccinated, causing death or serious long-term health effects such as blindness, mental retardation or amputations. But early symptoms can be hard to tell apart from other illnesses common in children.

Dr. Karen Midthun, director of the FDA's center for biologics, said Menhibrix is the first meningococcal vaccine that can be given to children as young as six weeks.

"(Meningitis) is one of those diseases that although not common, when it occurs it's absolutely devastating and horrible," said Dr. Len Friedland, vice president of clinical and medical affairs for Glaxo in North America.

"It presents to the doctor when a child just looks ill, and within 18 to 24 hours, they're on the deathbed in the hospital. ... To be able to have a vaccine to prevent meningitis is really a great day," he said.

The vaccine targets the C and Y strains of meningococcal bacteria, as well as Hib bacteria, which is short for Haemophilus influenzae type b. Hib disease was the most common cause of bacterial meningitis in children under the age of 5 before vaccines for the strain became common.

The B, C, and Y strains cause most cases of meningococcal disease in the United States - although there is no vaccine for the B strain, Glaxo said.

The vaccine's safety was tested in 7,500 children in the United States, Mexico and Australia. The vaccine is given in four doses, and common side effects included pain, redness and swelling at the injection site, irritability and fever.