Navigation Links
Varicella vaccine has long-term effectiveness against chicken pox

OAKLAND, Calif., April 1, 2013 Chicken pox, the childhood affliction of earlier generations, has been largely neutralized by the varicella vaccine, according to a new study by the Kaiser Permanente Vaccine Study Center, which appears in the current online issue of Pediatrics.

The 14-year study followed 7,585 children who were vaccinated in 1995, when they were 12 to 23 months old, to assess the long-term effectiveness of the vaccine and the impact on the epidemiology of varicella (chicken pox) and herpes zoster (shingles). Researchers also observed the impact of the second dose of varicella vaccine, introduced in 2006.

The varicella vaccine was licensed in the United States in 1995, and recommended soon after by the Advisory Committee on Immunization Practices for routine administration to children. Prior to that, chicken pox was ubiquitous, with more than 90 percent of young people experiencing infection by the age of 20.

Over the entire follow-up period, the incidence rate of chicken pox in this cohort was 9 to 10 times lower than corresponding rates in unvaccinated children of the same age in the pre-vaccine era. This resulted in an overall vaccine effectiveness rate of approximately 90 percent.

"Clearly, the vaccine is a very effective tool in preventing or limiting the severity of chicken pox in young people," said Randy Bergen, MD, chief of outpatient pediatrics at Kaiser Permanente's Walnut Creek Medical Center and a pediatric infectious disease consultant. "As with any vaccine, though, the rate of vaccination has a huge impact on effectiveness. The more children vaccinated, the more effective the vaccine is for the entire community. At Kaiser Permanente, our use of a comprehensive electronic health record, KP HealthConnect, enables us to quickly identify children in the targeted age ranges who have not been vaccinated, and to reach out to their parents to ensure they get the shots. Keeping vaccination rates high confers benefit on the community as a whole because there are fewer children who can contract and spread the virus."

A total of 1,505 breakthrough cases of chicken pox were reported within the study cohort of 7,585 children in the 14 years following varicella vaccination. "Breakthough cases" are so named because they occur despite the child having received the varicella vaccine; the virus "breaks through" the defenses afforded by the vaccine. Cases were classified as "mild" (less than 50 lesions), "moderate" (51 to 300 lesions) and "severe" (more than 300 lesions). Very few cases were severe (only 28 of 7,585 children over 14 years), whereas in the pre-vaccine era most children experienced severe symptoms. Prevention of moderate to severe disease was achieved with one dose of varicella vaccine; no cases were reported after the second dose.

The incidence rate of breakthrough varicella steadily decreased over time and no increase was observed during the 14 years of follow-up. The apparent increase in the vaccine's effectiveness over time, according to lead author Roger Baxter, MD, co-director of the Kaiser Permanente Vaccine Study Center, "is likely the result of vaccine failure occurring early, while breakthroughs became rare due to high vaccine effectiveness both directly and through herd immunity."

The continuing decline in breakthrough rates observed in 2008 and 2009 may have been the result of the implementation of the second dose in 2006, researchers said. The second dose of varicella is typically given at ages 4 to 6 years. However, it could potentially be of more benefit if given early after the first dose if varicella is circulating by increasing protection for infants too young to receive the vaccine and immune-compromised children who cannot receive a live vaccine.

The risk of herpes zoster, commonly known as shingles, was not increased in vaccinated children, and appeared to be lower in vaccinated children than in the pre-vaccine era. There were 46 confirmed cases of shingles among the cohort, suggesting an approximately 40 percent decreased incidence of herpes zoster in vaccinated children.


Contact: Catherine Hylas Saunders
Kaiser Permanente

Related medicine news :

1. Study Suggests Vaccine May Help Kids With Brain Cancer
2. Young girls more likely to report side effects after HPV vaccine
3. Preteens More Likely to Report HPV Vaccine Side Effects
4. Vaccine yielded encouraging long-term survival rates in certain patients with NSCLC
5. Early Study Finds Some Promise for Lung Cancer Vaccine
6. From a Failed Vaccine, New Insights Into Fighting HIV
7. From herd immunity and complacency to group panic: How vaccine scares unfold
8. Brain Tumor Vaccine Shows Promise in Early Trial
9. Army researcher develops potential vaccine carrier
10. A physicians guide for anti-vaccine parents
11. Shingles Vaccine Safe, Underutilized, Study Says
Post Your Comments:
(Date:6/26/2016)... ... June 26, 2016 , ... On June 10-11, 2016, ... the 2016 Cereal Festival and World’s Longest Breakfast Table in Battle Creek, MI, where ... city’s history as home to some of the world’s leading providers of cereal and ...
(Date:6/26/2016)... ... June 26, 2016 , ... Many women ... diagnosed with endometriosis. These women need a treatment plan to not only alleviate ... that can help for preservation of fertility and ultimately achieving a pregnancy. The ...
(Date:6/25/2016)... ... June 25, 2016 , ... "With 30 hand-drawn hand gesture animations, ... Christina Austin - CEO of Pixel Film Studios. , ProHand Cartoon’s package transforms ... Final Cut Pro X . Simply select a ProHand generator and drag it above ...
(Date:6/25/2016)... ... June 25, 2016 , ... On Friday, June 10, Van Mitchell, ... at Work award to iHire in recognition of their exemplary accomplishments in worksite health ... annual Maryland Workplace Health & Wellness Symposium at the BWI Marriott in Linthicum Heights. ...
(Date:6/24/2016)... , ... June 24, 2016 , ... June 19, 2016 ... dangers associated with chronic pain and the benefits of holistic treatments, Serenity Recovery ... are suffering with Sickle Cell Disease. , Sickle Cell Disease (SCD) is a disorder ...
Breaking Medicine News(10 mins):
(Date:6/24/2016)... June 24, 2016 Research ... "Structural Electronics 2015-2025: Applications, Technologies, Forecasts" ... In-Mold Electronics, Smart Skin, Structural Health ... Structural electronics involves electronic and/or electrical ... structures, replacing dumb structures such as vehicle bodies ...
(Date:6/24/2016)... , June 24, 2016 Research ... World Market for Companion Diagnostic Tests" report to their ... Market for Companion Diagnostics The World Market ... and personalized medicine diagnostics. Market analysis in the report includes ... Test Market (In Vitro Diagnostic Kits) by Region (N. America, ...
(Date:6/24/2016)... KNOXVILLE, Tenn. , June 24, 2016 /PRNewswire/ ... market providing less invasive and more durable cerebrospinal ... million in funding.  The Series-A funding is led ... the Lighthouse Fund, and other private investors.  Arkis, ... less-invasive neurosurgical instrumentation and the market release of ...
Breaking Medicine Technology: