After vaccination with the live attenuated varicella zoster (chicken pox) virus (VZV), anti-VZV titers decline and reactivation of the latent infection can occur. While this can boost immunity to the natural infection, the drawback is that reactivation may be accompanied by mild symptoms.
Researchers followed 4,631 children who had received the vaccine. In children who initially had high anti-VZV titers, titers tended to decline during the 4 years of the study, while in those whose initial response to the vaccine was weaker, titers increased over time.
The investigators identified 508 children who experienced a substantial increase, or boost, in VZV immunity. This rate was considerably higher than that expected from exposure to wild-type virus, and hence is attributable to reactivation of the vaccine virus. When titers remain high, the virus is dormant, but as immunity declines, the latent virus wakes up. In most cases, the boost will not lead to any symptoms more serious than a mild fever or a few spots.
Nature Medicine 2000;6:381-382,451-454
Another article that was forwarded by Michael Belkin who is noted fro his excellent testimony to Congress on the vaccine issue. He comments "clinically inconsequential?" What about the risk of complications (encephalitis), which is supposed to be the big reason to vaccinate against a relatively benign disease? Not mentioned anywhere. What about Shingles? Notice one of the authors is an FDA crony.
This study was probably designed to refute growing doubts about the efficacy of the Varicella vaccine. It does the opposite. It admits it doesn't work and actually causes chickenpox years later. Up to 30% of children vaccinated with the chicken pox vaccine could have a recurrence of chicken pox.