The Food and Drug Administration (FDA) has approved a "four-in-one vaccine" for children.

The new vaccine is a combination shot for measles, mumps, and rubella with a second vaccine for chickenpox.

According to maker Merck & Co., the vaccine, called Proquad, will be given to children ages 12 months to 12 years.

"The vaccine is considered safe and effective for the approved indication and combines already approved vaccines," an FDA spokesperson said.

Mark Feinberg, M.D., Ph.D., vice president of policy, public health, and medical affairs at Merck Vaccine Division, says the new vaccine will "reduce the gap that exists in the United States between vaccination rates for chickenpox, which were estimated at 87.5% in 2004, and rates for measles, mumps, and rubella, which were an estimated 93% in 2004."