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Oral Flu Vaccine Equivalent to Injectable in Early Study
According to study data reported at the 15th Annual World Vaccine Congress, held October 13–15 in Brussels, Belgium, a tablet H1N1 influenza vaccine provided protective immunity comparable with that of currently licensed injectable flu vaccines, as measured by the hemagglutinin inhibition assay (HAI), the established correlate of protection.
According to the product’s developer (Vaxart, Inc.), a tablet vaccine could be brought directly to the user, such as in the workplace or at school, and avoids the need to worry about needles. A tablet vaccine might also be manufactured and distributed more quickly than current injectable vaccines, a factor that could be critical when responding to a pandemic or outbreak.
The new data were obtained from a phase I clinical study of a tablet vaccine candidate for H1N1 seasonal influenza. The randomized, double-blind, placebo-controlled study enrolled 24 healthy volunteers 18 to 49 years of age, who received either the vaccine or placebo in tablet form in a single administration.
In subjects receiving the tablet H1N1 vaccine, 75% (9/12) fully seroconverted, as measured by the HAI — a response rate equivalent to that reported for licensed injectable vaccines. In addition, HAI geometric mean titers increased 7.7-fold, which was also within the range of injectable vaccines. None of the subjects receiving placebo (0/12) seroconverted.
In addition, the tablet H1N1 vaccine induced four-fold increases in neutralizing antibody titers in 92% of the subjects (11/12) in that group, as measured by microneutralization (MN) titers (an increasingly recognized marker of protective immunity), compared with none of the 12 subjects in the placebo group. MN geometric mean titers increased 23-fold, exceeding rate increases reported for most injectable vaccines. The tablet vaccine also generated strong mucosal and cellular immune responses in 92% of the subjects (9/12) in that group, suggesting that the tablet vaccine might offer broader protection than that of currently licensed injectable flu vaccines.
Source: Vaxart, Inc.