About the Vaccine
A new shingles vaccine called Shingrix was licensed by the U.S. Food and Drug Administration (FDA) in 2017. CDC recommends that healthy adults 50 years and older get two doses of Shingrix, 2 to 6 months apart. Shingrix provides strong protection against shingles and PHN. Shingrix is the preferred vaccine, over Zostavax.
Zostavax (zoster vaccine live), when reconstituted as directed on the package label using the supplied diluent, contains a minimum of 19,400 PFU of Oka/Merck strain of varicella zoster virus. The minimum potency of Zostavax is at least 14 times the potency of varicella vaccine (Varivax®), which contains a minimum of 1,350 PFU, and is similar in potency to the varicella zoster virus content of measles-mumps-rubella-varicella vaccine (ProQuad®).
Zostavax is administered subcutaneously as a single dose in the deltoid region. The vaccine should not be injected intramuscularly. However, it is not necessary to repeat vaccination if it is administered intramuscularly.
The vaccine should be administered immediately after reconstitution to minimize loss of potency. Any unused vaccine should be discarded if not used within 30 minutes.
In adults vaccinated at age 60 years or older, vaccine efficacy wanes steeply the first year after vaccination, and protection by 6 years after vaccination is less than 35%. Therefore, adults receiving the vaccine before age 60 years might not be protected when their risks for herpes zoster (shingles) and its complications are highest.
Studies are ongoing to assess the duration of protection from one dose of Zostavax and the need, if any, for booster doses.
There are no comprehensive data on the effectiveness of Zostavax in treating herpes zoster once it occurs, and the vaccine is not licensed for this indication.