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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
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