Zostavax is the name of the live vaccine developed by Merck & Co. that prevents the development of shingles, also known as herpes zoster. The Zostavax vaccine was approved by the U.S. Food and Drug Administration in May 2006. The U.S. Centers for Disease Control and Prevention recommends Zostavax for all adults aged 60 and older. Zostavax works in much the same way as other vaccines.
Shingles
Shingles is a painful rash caused by the virus, varicella zoster, or VZV. This virus also causes chickenpox mostly in children. After having chickenpox the virus is not eradicated from the body and the CDC reports that about 25 percent of people exposed to the virus early in life develop shingles decades later. VZV lies dormant in nerve cells and for unknown reasons can travel in nerves and cause a painful rash in the tissues supplied by the nerve. The rash typically lasts two to four weeks, but the associated pain can linger for months or years.
Clinical Studies
The CDC reports that Zostavax reduced the occurrence of shingles by nearly 50 percent and decreased the associated chronic pain by 67 percent in a population of 38,000 people who were older than 65. This study also reports that the vaccine is most effective in individuals between the ages of 60 and 69. In people older than 69, the occurrence of shingles was decreased only by one-third in vaccinated people; however, the severity of disease was significantly reduced also in older individuals.
Vaccine Actions
Zostavax is a live attenuated vaccine, meaning that the virus has been treated to remove its virulent actions. This type of vaccine provokes a strong immune response in healthy adults. The Zostavax vaccine is much more potent, but similar to the chickenpox vaccine. The occurrence of shingles is related to a re-activation of the virus and a decrease in immune system actions against the virus that occurs with age. The vaccine boosts immune system activity to eradicate the active virus and maintain the virus in its dormant state.
Vaccine Contraindications
The FDA recommends that people older than 60 not be given the vaccine if they have had an allergic reaction to components of the vaccine, such as gelatin or neomycin, have a weakened immune system, have had bone marrow or lymphatic system cancers or those who have active untreated tuberculosis.
Side Effects
Few side effects have been reported in people administered the shingles vaccine. The reported side effects include mild pain, tenderness and skin rash at the site of injection and headache. The Shingles Prevention Study, which was one of the largest clinical trials ever to be conducted, was led by the Department of Veterans Affairs. This study on more than 38,000 people did not find a significant increase in adverse health events associated with Zostavax vaccination.
