U.S. researchers have found the United States has experienced a significant decline in deaths related to chickenpox since a vaccine for the virus was introduced in 1995.

Researchers at the Center for Disease Control and Prevention reached this conclusion after examining cause-of-death records between 1990 and 2001.  They discovered that in the years 1990 through 1998, there was an average of 145 deaths per year in which chickenpox was a factor. Between 1999 and 2001, the average number of deaths dropped to 66.

A study published Thursday, says the sharpest decline was in children ages one through four. It is not clear yet how vaccinations will affect deaths related to shingles, a painful rash caused by a reawakening of the dormant chickenpox virus.

Some information for this story provided by AP and Reuters.