Zoster and Influenza Vaccines Can Be Administered Concomitantly to Adults

November 16, 2007 — In adults aged 50 and older, it is safe and effective to administer herpes zoster vaccine Zostavax (Merck) concomitantly with inactivated influenza vaccine, according to results of a large randomized, controlled study conducted at 20 sites in the US and Europe.
The U.S. Centers for Disease Control and Prevention's Advisory Committee on Immunization Practices (ACIP) has unanimously recommended that Americans aged 60 and older receive Zostavax vaccine to prevent herpes zoster.
Clinical trials have shown that Zostavax significantly reduces the incidence of herpes zoster and postherpetic neuralgia and moderates symptoms in patients who do have outbreaks.
As both Zostavax and influenza vaccine are recommended for older adults, it would be convenient to administer them simultaneously, note Dr. Boris Kerzner, from Health Trends Research, Baltimore, Maryland and colleagues in a report in the November issue of the Journal of the American Geriatrics Society.
The researchers evaluated the safety and immunogenicity of concomitant and sequential administration of the two vaccines in adults older than age 50.
A total of 382 subjects in the concomitant vaccine group received influenza vaccine and Zostavax at separate injection sites on one day and placebo at week 4. The 380 subjects in the sequential arm received influenza vaccine and placebo at separate injection sites at day 1 and Zostavax at week 4.
Dr. Kerzner and colleagues found that concomitantly administered Zostavax and influenza vaccine was "generally well tolerated" and there was no difference in antibody responses between concomitant and sequential administration.
"All varicella-zoster virus and influenza immunogenicity endpoints were met," they report.
Specifically, varicella-zoster virus antibody geometric mean titers 4 weeks post-vaccination for the concomitant and sequential groups were 554 and 597 U/mL, respectively, according to glycoprotein enzyme-linked immunosorbent assay.
"Estimated geometric mean titer ratios (concomitant/sequential) for influenza strains A(H1N1), A(H3N2) and B were 0.9, 1.1 and 0.9, respectively," according to the investigators. Influenza seroconversion rates were comparable across concomitantly and sequentially vaccinated subjects, with more than 85% achieving titers "meeting regulatory criteria."
Supporting the safety of concomitant administration, the researchers found that the overall incidence of systemic adverse events was similar in both vaccination arms (roughly 33%), and only about 5% of subjects in each arm reported vaccine-related systemic adverse events; no serious adverse events related to Zostavax were observed.
"With the ACIP recommendation for universal use of Zostavax in older adults, plus data presented from this study," Dr. Kerzner and colleagues suggest, "a change in the adult vaccination schedule could occur. The data presented here support the concomitant administration of Zostavax and influenza vaccine for older adults."
J Am Geriatr Soc. 2007;55:1499-1507.