One Dose of H1N1 Vaccine May Offer Substantial Protection

Preliminary studies suggest single-dose and adjuvant strategies can stretch vaccine supply
By Jeff Muise
HealthDay Reporter

FRIDAY, Sept. 11 (HealthDay News) -- Preliminary research indicates that just a single dose of the 2009 H1N1 vaccine can substantially increase protective antibodies, but vaccinations with seasonal flu vaccine provide minimal cross-reactive antibody response, according to several studies published online Sept. 10 in the New England Journal of Medicine.

In one study, Michael E. Greenberg, M.D, of CSL in Parkville, Australia, and colleagues evaluated the efficacy of a single dose of an inactivated split virus 2009 H1N1 vaccine among 240 subjects. At day 21, antibody titers of at least 1:40 were seen in 96.7 and 93.3 percent of subjects receiving the 15-µg and 30-µg doses, respectively. In the second study, Tristan W. Clark, of the University of Leicester in the United Kingdom, and colleagues randomized 175 adults to receive 2009 H1N1 vaccine in adjuvanted and non-adjuvanted forms. The MF59-adjuvanted vaccine was found to produce antibodies at a level likely to offer protection within 14 days after just one dose.

In a third study, Kathy Hancock, Ph.D., of the U.S. Centers for Disease Control and Prevention in Atlanta, and colleagues measured cross-reactive antibodies to 2009 H1N1 in serum samples from people vaccinated for the 1976 influenza or recently for seasonal flu. While the 1976 vaccine was linked with increased cross-reactivity, seasonal flu vaccination was not significantly associated with cross-reactivity across any age group.

"In our current global situation, in which demand for influenza vaccine greatly exceeds supply, dose-sparing strategies are needed. Fewer or partial does and the use of adjuvants can all contribute to increased global vaccine supply," writes the author of an accompanying editorial.

The authors of the Greenberg study reported being employees of CSL. Several of the authors in the Clark and Hancock studies reported financial relationships with a variety of pharmaceutical companies.

Abstract - Greenberg
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Abstract - Clark
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Abstract - Hancock
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