The results of a phase 1 study are a positive first step towards an oral flu vaccine, researchers say.

In the double-blind trial 24 healthy adults were randomised to either a monovalent influenza A H1N1 oral vaccine or placebo.

After immunisation 11 of the 12 vaccine-treated participants had a four-fold increase in haemagglutination inhibition titres (group geometric mean fold rise of 7·7) and microneutralisation titres (group geometric mean fold rise of 29).

“Because influenza protection has been known to correlate to a four-fold increase in haemagglutination inhibition response the ability to elicit these responses in a human clinical trial is a major achievement, the authors wrote in their study published in Lancet Infectious Diseases.

Although several studies will need to be completed that address issues such as interference and repeated seasonal use, these results look encouraging for safety and immunogenicity, they concluded.

The study was funded by Vaxart Inc and the research investigators were employees of the company.