Chickenpox is highly contagious and develops from the varicella-zoster virus. Generally harmless, chickenpox can develop into a severe disease if untreated. Chickenpox appears as red, itchy dots and in those who are not vaccinated can contribute to fever.
Prior to the vaccination emerging, roughly four millions Americans developed chickenpox annually. An estimated 11,000 Americans visited the hospital for chickenpox and roughly 150 died; these statistics were reported by the Centers for Disease Control and Prevention (CDC). A second dosage vaccination was introduced in 2006 and has led to an even further reduction of chickenpox cases.
Researchers from the CDC compiled data from national health care claims from 1994 to 2012. What they found was 93 percent fewer visits to hospitals for chickenpox in 2012 as compared to 1994 where the vaccine was not introduced yet. Furthermore, there was a reduction of outpatients in 2012 by 84 percent compared to pre-vaccination days. When the second dose was introduced, outpatients dropped 60 percent between 2006 and 2012.
Study co-author, Jessica Leung, said, “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. 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.”
The biggest decline in chickenpox cases were seen among children aged one to 19. This population is heavily targeted to receive the vaccine. The vaccine is not recommended for children 12 months or younger or in adults who are not immunized, and yet both groups saw a reduction in chickenpox cases as well. This suggests the possibility of herd immunity.
Researchers suggest testing needs to be conducted to better distinguish chickenpox from other rashes, as they noted an increase in outpatients with the virus between 2003 and 2012. This distinction can better help reduce cases of chickenpox over time.
The findings were published in the Journal of Pediatric Infectious Diseases Society.
Sources:
http://www.pids.org/news/478-chickenpox-continues-to-decline-in-u-s-thanks-to-vaccination.html