A study published in the Journal of the Pediatric Infectious Diseases Society suggests the decline of Varicella (chickenpox) continues in the United States as vaccination with the two-dose coverage has increased, Medscape reports.

The findings also revealed herd immunity, protecting those who were not vaccinated.

"We found that, in our study, rates for varicella in the U.S. continued to decline as the varicella vaccine program has become fully implemented," coauthor Jessica Leung, MPH, from the Centers for Disease Control and Prevention in Atlanta, Georgia, said in a news release, according to Medscape.

"We saw significant declines in rates of varicella after the one-dose vaccine was recommended in 1995 in the U.S., and we're continuing to see additional declines in varicella after two doses were recommended in 2006."

According to the Centers for Disease Control and Prevention, the one-dose varicella vaccination program that began in 1996 led to a decrease in varicella prevalence with an 88 percent decline in varicella-related hospitalizations and a 59% decline in outpatient visits during 1994 to 2002.

However, a two-dose vaccination program was introduced in 2007 after continued sporadic outbreaks.

Since then, Children and adolescents aged one to 19 years had the greatest decrease in varicella outpatient visits and hospitalizations. However, largely unvaccinated populations also registered decrease in outpatient visits and hospitalizations, suggesting the possibility of herd immunity.

"[A]fter 16 years, the varicella vaccination program continues to mature and to provide increasing beneficial national impact," the study authors conclude. "We provide evidence from our large study population that outpatient visit and hospitalization rates continue to decline, as does case severity."