Merck's ($MRK) Zostavax varicella zoster virus (VZV) vaccine has been approved for use in adults over 50 for the prevention of shingles, and it cuts the risk by around 70% in people who have had chickenpox. A paper presented at the American Academy of Dermatology (AAD) 70th Annual Meeting looked at the effectiveness of a booster shot of a VZV vaccine, and found that, while there is a significant immune response after the first vaccination, it doesn't increase significantly after the second shot.
These results also could suggest that the vaccine is unlikely to prevent shingles after an initial attack.
"If there was a strategy that could increase the effectiveness of the vaccine, that would be very useful," author Rana Mays, M.D., from the Center for Clinical Studies in Webster, TX, told Medscape Medical News. "Unfortunately, this study did not show that. I am not sure we know definitively that there is no point to revaccination, but in terms of this study, we didn't see a big boost in their antibody titer."
Shingles (herpes zoster) is an unpleasant follow-on from a childhood bout of chickenpox; viruses that have lain dormant in the nerves for what could be many years get reactivated, leading to stripes of blisters, with pain, itching or tingling. Post-herpetic neuralgia, after the blisters have cleared, can last for years.
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