NEW ORLEANS – Varicella zoster virus DNA was detected in subjects’ saliva for a month after immunization with the Zostavax herpes zoster vaccine in a prospective study.
Genotypic analysis demonstrated that the varicella zoster virus that was present in saliva was indeed the Zostavax live attenuated vaccine virus, Dr. Catherine M. DiGiorgio said at the annual meeting of the American Academy of Dermatology.
The next step is to determine whether this virus that is being shed in saliva and at inoculation sites after immunization is infectious. If so, it’s possible that herpes zoster infection might be transmitted through recently immunized individuals.
Although that would be highly unwelcome news, there is a potential upside to the finding that varicella zoster virus (VZV) can be detected in saliva: "It possibly could have use in clinical practice, allowing detection of shingles prior to development of the rash, enabling earlier start of antiviral therapy, and decreasing the duration of shingles and the pain of post-herpetic neuralgia," said Dr. DiGiorgio of the center for clinical studies at the University of Texas, Houston.
She reported on 19 men and 17 women, all healthy and older than age 60 years, who received the Zostavax vaccine. Skin and saliva samples were obtained for the next 4 weeks. None of the subjects shed VZV in their saliva prior to immunization.
Half the subjects had VZV DNA present in swabs obtained from skin inoculation sites at 10 minutes after immunization. In all, 21 subjects (58%) had VZV DNA in their saliva shortly after vaccination. At 2 weeks, 11 subjects still had viral shedding in saliva, as did 10 at day 20 and 2 subjects at day 28.
Transmission of the Oka/Merck strain of VZV has been documented after chicken pox vaccination, but thus far not following immunization with the company’s Zostavax vaccine. The Zostavax package insert warns newly vaccinated individuals to avoid contact with infants, immunosuppressed individuals, and pregnant women who haven’t had chickenpox or been vaccinated against it, but the insert doesn’t specify why or provide a duration, Dr. DiGiorgio noted.
Roughly 1 million cases of herpes zoster occur annually in the United States, half in adults aged 50 years or older. Dr. DiGiorgio and her coworkers have recently shown that a positive family history increases the risk of developing shingles, and that patients with post-herpetic neuralgia can shed VZV in their saliva for years.
Dr. DiGiorgio declared that she serves as a subinvestigator in studies sponsored by Inhibitex and NeurogesX.
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